WO1995004401A1 - Circuit filtrant - Google Patents
Circuit filtrant Download PDFInfo
- Publication number
- WO1995004401A1 WO1995004401A1 PCT/JP1994/001234 JP9401234W WO9504401A1 WO 1995004401 A1 WO1995004401 A1 WO 1995004401A1 JP 9401234 W JP9401234 W JP 9401234W WO 9504401 A1 WO9504401 A1 WO 9504401A1
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- WIPO (PCT)
- Prior art keywords
- transistor
- emitter
- source
- grounded
- circuit
- Prior art date
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/45179—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using MOSFET transistors as the active amplifying circuit
- H03F3/4521—Complementary long tailed pairs having parallel inputs and being supplied in parallel
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
- H03F3/45—Differential amplifiers
- H03F3/45071—Differential amplifiers with semiconductor devices only
- H03F3/45076—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier
- H03F3/4508—Differential amplifiers with semiconductor devices only characterised by the way of implementation of the active amplifying circuit in the differential amplifier using bipolar transistors as the active amplifying circuit
- H03F3/45085—Long tailed pairs
- H03F3/45089—Non-folded cascode stages
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/04—Frequency selective two-port networks
- H03H11/12—Frequency selective two-port networks using amplifiers with feedback
- H03H11/1291—Current or voltage controlled filters
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45018—Indexing scheme relating to differential amplifiers the differential amplifier amplifying transistors have added cross couplings
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45022—One or more added resistors to the amplifying transistors in the differential amplifier
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45024—Indexing scheme relating to differential amplifiers the differential amplifier amplifying transistors are cascode coupled transistors
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2203/00—Indexing scheme relating to amplifiers with only discharge tubes or only semiconductor devices as amplifying elements covered by H03F3/00
- H03F2203/45—Indexing scheme relating to differential amplifiers
- H03F2203/45034—One or more added reactive elements, capacitive or inductive elements, to the amplifying transistors in the differential amplifier
Definitions
- the present invention relates to a filter circuit suitable for integrated circuit formation, for example, comprising a transistor or a field effect transistor for controlling a frequency band in a signal receiver amplifier circuit in an optical communication system.
- a plurality of filter circuits are used according to purposes.
- an equalizing amplifier circuit requires a low-pass filter circuit to obtain an optimum frequency band and an optimum cutoff characteristic determined by a balance between waveform interference and a noise band
- a timing clock amplifier circuit requires a low-pass filter circuit. Therefore, a low-pass filter circuit, a high-pass filter circuit, and a band-pass filter circuit are needed to suppress jitter caused by circuit noise and to prevent malfunction due to harmonic components.
- the transmission speed of optical communication systems has been increased, 2.4 Gb / s systems have already been put into practical use, and development of systems of about 5 GbZs to 1 O GbZs has been urgently required.
- the operable frequency of the filter circuit applied to the above-mentioned amplifier circuit also needs to be from several GHz to 10 GHz.
- the cutoff frequency and A filter circuit with a variable center frequency is required.
- the circuits that make up the optical communication system have evolved from discrete circuits to integrated circuits, and the technology of integrating analog and digital circuits on the same semiconductor chip has also been put into practical use. It is desirable that the filter circuit be compatible with such technology. An active filter circuit can meet such a demand.
- the first active filter circuit was developed with an operational amplifier and a CR circuit. This is because the circuit can be easily designed by taking advantage of the high gain of the operational amplifier and the characteristics of very high input impedance and low output impedance.
- the operational amplifier has a narrow usable band and cannot be applied to the high-speed system described above. Therefore, the importance of the technology of constructing an active filter circuit using a broadband active element is increasing.
- a filter circuit that can change the frequency band of the circuit over a wide range is required.
- FIG. 48 is a diagram showing a configuration example of an optical signal receiving unit in the optical communication system as described above.
- 1 is a light receiving element
- 2 is an equalizing amplifier
- 3 is a slice amplifier.
- 4 are timing extraction circuits
- 5 is a filter
- 6 is a limiter amplifier circuit
- 7 is an identification circuit.
- the light receiving element 1 converts an optical signal into an electric signal
- the equalizing amplifier circuit 2 linearly amplifies the electric signal converted by the light receiving element 1 to a predetermined amplitude.
- the circuit 3 is for slicing the signal amplified by the equalizing amplifier circuit 2.
- the timing extraction circuit 4 extracts the frequency timing of the signal amplified by the equalization amplification circuit 2 and outputs a clock, and the filter 5 ′ reduces noise included in the clock. Is the limit
- the evening amplifier circuit 6 amplifies the mouthpiece that has passed through the filter 5 to a predetermined amplitude.
- the discrimination circuit 7 discriminates the data signal amplified by the slice amplification circuit 3 using the clock signal amplified by the limiter amplification circuit 6, and outputs data.
- optical signal receiving section By configuring the optical signal receiving section as described above, it is possible to amplify a signal that has been degraded due to transmission over a long distance in an optical communication system.
- the equalizing amplifier circuit 2 if the frequency band is too wide, the noise band will be widened and the S / N ratio will be poor. Conversely, if the frequency band is too narrow, waveform interference will increase. However, the receiving sensitivity deteriorates.
- the equalizing amplifier circuit 2 has an optimum frequency band according to the applied transmission speed due to the balance between the noise band and the waveform interference, so that the equalizing amplifier circuit 2 has good characteristics in the integrated circuit.
- An active low-pass filter is required.
- the limiter amplifier circuit 6 is designed to suppress jitter caused by noise of the limiter amplifier circuit and to prevent malfunction of the circuit due to harmonic components accompanying the limiter amplification.
- a tuning characteristic is required, and an active filter circuit such as a low-pass filter circuit, a high-pass filter circuit, or a band-pass filter circuit is required to realize the tuning characteristic in the integrated circuit.
- a frequency band variable filter circuit capable of changing the characteristics so as to cope with the fluctuation of the band due to the fluctuation of the manufacturing of the integrated circuit constituting each of the above-described amplifier circuits or unexpected peaking is required. become.
- FIG. 49 shows a conventional active low-pass filter circuit.
- T 17 a and T 17 b are transistors serving as input transistors
- T 18 a and T 18 18b is a transistor that forms a resistor that determines the cutoff characteristic and is an output transistor.
- T19a and T1'9b are transistors that form a capacitor that determines the cutoff characteristic.
- R18a and R1 8b is a resistor for converting an input voltage to a current
- R19a and R19b are resistors for converting a current to a voltage to generate an output voltage.
- the circuit shown in FIG. 49 is composed of the first order of RC based on the resistance with the transistors 18a and T18b and the capacitance with the transistors T19a and Tl9b. A filter circuit having a cutoff characteristic is obtained.
- the resistance in view of the transistors T18a and T18b is the current amplification constant of the transistor T18a and T18b / 3. If T is large enough, the emitter resistance is re, and the capacitance that allows for the transistors T19a and T19b is the connection point of the emitters of the transistors T19a and T19b. since but a virtual ⁇ over scan, the junction capacitance C JE junction capacitance C JC :, E Mi jitter junction of the collector junction, and since the sum of E Mi jitter diffusion capacitance C d, the cutoff frequency f c following Is given by
- the filter circuit shown in FIG. 49 uses the fact that C d (C D »C JE, C JC holds in a normal bias) is proportional to the emitter current.
- This circuit is a balanced circuit that applies an input voltage between the bases of the transistor Tl7a and the transistor T17b, and takes out the output from the collector of the transistor T18a and the transistor T18b.
- transistor Apply an input voltage between the base of T17a or the transistor T17b and the ground; apply an input voltage between the collector of the transistor T18a or the transistor T18b and the ground and obtain an unbalanced circuit.
- one of the input and output can be used as a balanced circuit and the other as an unbalanced circuit.
- the circuit shown in Fig. 49 is a primary filter circuit (having primary cutoff characteristics)
- a secondary filter circuit having secondary cutoff characteristics
- a circuit having the same configuration as that shown in Fig. 49 is connected in cascade, or a coil (L) and a capacitor (C) are used to realize a second-order characteristic with an LCR filter circuit.
- the primary active filter circuit is cascaded as in the former case, there is a problem that the cut-off frequency is reduced.
- the filter shown in FIG. Since it is necessary to add a voltage shift circuit to the circuit, there is a problem that the circuit scale of the filter circuit becomes large.
- FIG. 50 to FIG. 52 are diagrams showing configuration examples of a conventional band variable filter circuit.
- the bases of transistors 501a and 501b forming a differential pair are connected to the emitters of the cascode transistors 401a and 401b, and the cascode The frequency band is obtained by using the emitter resistance of the transistors 401 a and 401 b and the rejection of the differential pair transistors 501 a and 501 b by the emitter diffusion capacitance C d (c IE).
- Configuration example of the circuit that controls It is. .
- the frequency band of the filter circuit can be controlled by controlling the emitter current IE of the differential pair transistors 501 a 501 b by the variable current source 70 1 b.
- the frequency band f of this filter circuit which is indicated by a band reduced by 3 dB, is the frequency band f of the circuit without a frequency band control circuit. It is determined by RC and the frequency band f CNTL with the frequency band control circuit.
- C JE is the base of the differential pair transistor 501 a 501 b, and is the coupling capacitance between the emitters.
- C JC is the base collector of the differential pair transistor 501 a 501 b. is between coupling capacitance
- r e is the cascode transistor
- the maximum frequency band f CNTL (MAX) and the minimum frequency band ⁇ CNTL ( M1N ) of the frequency band control circuit can be expressed by the following equations, respectively.
- the frequency band control circuit is configured such that CNTCNT L (MIN) f ORG and f CNTL (MA) from these equations, the frequency band f of the entire circuit can be expressed as
- FIG. 51 shows an example of a result obtained by simulating the frequency band variable characteristics of the above-described circuit by SPIC E, and FIG.
- the frequency band can be narrowed by increasing the emitter current IE.
- the filter circuit shown in Fig. 52 uses the transistor transition frequency ⁇ ⁇ ⁇ (frequency at which the current amplification factor when the emitter is grounded is 1) Is dependent on the collector current of the transistor, the two differential pairs are connected in parallel, and the distribution ratio of the current flowing through both is controlled by the current value variable circuit, thereby reducing the frequency band. It is a configuration example in which control is performed.
- the frequency band f of the entire circuit becomes ⁇ ⁇ f ⁇ f CNTL (MA x). ( ⁇ F. RC ), and the maximum frequency band deteriorates compared to the case without the control circuit, and the frequency band variable width There is a problem that it is difficult to control over a wide range.
- the present invention has been made in view of the above problems, and is applicable to an integrated circuit having a secondary cutoff characteristic that can stably change a frequency band over a wide range without deteriorating a maximum frequency band of the entire circuit.
- the purpose is to provide a filter circuit. Disclosure of the invention
- the present invention is configured such that one end is connected to the first transistor whose base or gate is grounded at a high frequency via the first resistor, and the other end is connected to the emitter or source of the first transistor.
- High frequency grounded second resistor And a capacitor, and a circuit that receives a current at a connection point between the second resistor, the capacitor and the first transistor, and outputs a collector or drain current of the first transistor.
- the present invention provides a method in which a base or a gate is connected to one end of a first resistor, a collector or a drain is grounded at a high frequency through an impedance including zero ohms, and a current equivalent to an emitter or a source is provided.
- a first transistor connected to a power source, a second resistor and a capacitor connected at one end to an emitter or source of the first transistor and the other end to a high frequency ground.
- the circuit has a circuit in which a voltage applied to the other end of the resistor is input and a voltage of an emitter or a source of the first transistor is output.
- the present invention provides a first transistor in which a base or a gate is grounded at a high frequency via a first resistor, and a collector or a drain is grounded at a high frequency via an impedance including zero ohms; One end is connected to the emitter or source of the first transistor and the other end is connected to the second resistor whose other end is grounded at high frequency and the emitter or source of the first transistor It is characterized by comprising a circuit having a capacitor and having a current at a connection point between the emitter and the source of the second resistor and the first transistor as an input, and a current at the other end of the capacitor as an output.
- the present invention provides a circuit in which a base or a gate is grounded at a high frequency via a first resistor, a collector or a drain is grounded at a high frequency via an impedance including zero ohms, and is equivalent to an emitter or a source.
- a capacitor having one end connected to the emitter or source of the evening, and a voltage applied to the other end of the capacitor as an input. It has a circuit that outputs the source voltage or the source voltage.
- the present invention provides a first transistor having a base or gate grounded at a high frequency via a first resistor, and a collector or drain grounded at a high frequency via an impedance including zero ohms.
- a capacitor connected at one end to the emitter or source of the first transistor and grounded at the other end at high frequency, and a second resistor connected at one end to the emitter or source of the first transistor And a circuit that receives a current at a connection point between the capacitor and the emitter or source of the first transistor as an input and outputs a current at the other end of the second resistor.
- the present invention provides a base or gate grounded at a high frequency via a first resistor, a collector or a drain grounded at a high frequency via an impedance including zero ohms, and an equivalent of an emitter or a source.
- a first transistor connected to a current source, a capacitor connected at one end to an emitter or source of the first transistor, and the other end grounded at a high frequency;
- a second resistor having one end connected to the emitter or the source of the first transistor, the voltage applied to the other end of the second resistor as an input, and the emitter or the source of the first transistor being input. It is characterized by having a circuit that outputs voltage.
- the present invention provides a first transistor in which a base or a gate is grounded at a high frequency via a first resistor, and a collector or a drain is grounded at a high frequency via an impedance including zero ohms, A capacitor connected at one end to the emitter or source of the first transistor and having the other end grounded at a high frequency; and providing a current at the connection point between the capacitor and the emitter or source of the first transistor.
- the circuit is characterized by having a circuit that takes as input an output of an emitter or source voltage of the first transistor.
- the present invention also provides a first transistor having a base or a gate grounded at a high frequency via a first resistor, and an equivalent current source connected to an emitter or a source, and a first transistor. And a capacitor having one end connected to the emitter or the source of the first transistor, and a circuit that receives the voltage applied to the other end of the capacitor as an input and outputs the collector or drain current of the first transistor as an output.
- collector or drain and the base or gate are grounded at a high frequency to the base or gate of the first transistor through an impedance including zero-mode, and are equivalent to the emitter or source.
- the emitter or source of the second transistor to which a variable current source is connected may be connected.
- the collector or drain is grounded at a high frequency to the base or gate of the first transistor by impedance including zero ohms, and an equivalent variable current source is connected to the emitter or source.
- the emitter or source of the second transistor may be connected, and the voltage applied to the base or source of the second transistor may be used as the input.
- the present invention relates to a frequency band variable filter circuit used in a signal receiving unit or the like of an optical communication system, wherein the signal path switching unit switches a signal transmission path of an input signal by changing an applied control voltage;
- the transmission path is characterized by comprising a frequency band control unit having a different band variable width, and a cascode transistor whose emitter or source is connected to the signal path switching unit via the frequency band control unit.
- the present invention provides a signal path switching unit comprising: an emitter or a source-grounded transistor having an emitter or a source grounded through a resistor including zero ohm; and a collector or a drain of the emitter or the source-grounded transistor.
- a frequency band control unit connected to the collector or drain of the transistor, and a frequency band control circuit connected to the collector or drain of the transistor.
- the cascode transistor consists of an emitter or a source connected to the collector or drain of the transistor via a resistor, and an emitter or a source grounded. It is characterized in that a signal voltage is applied to the base or gate of the transistor and a control voltage is applied to each base or gate of the transistor.
- the present invention provides an emitter or a source-grounded transistor whose emitter or source is grounded via a resistor including zero ohms, a transistor, a resistor, a frequency band control circuit, and a cascode transistor.
- a constant current source connected to the junction between the transistor and the resistor, an emitter or a source connected to the emitter or the source via a resistor, a transistor, a resistor, and a frequency band control circuit, respectively.
- a cascode transistor differential pair configuration is whose emitter or source is grounded via a resistor including zero ohms, a transistor, a resistor, a frequency band control circuit, and a cascode transistor.
- the present invention provides a signal path switching unit comprising an emitter or a source-grounded transistor grounded via a resistor including zero ohm, and a base or gate for each of the emitter or the source-grounded transistor. It is characterized in that a signal voltage and a control voltage are applied to the control unit.
- the present invention provides an emitter or a source-grounded transistor whose emitter or source is grounded via a resistor including zero ohms, a resistor, a frequency band control circuit, and a cascode transistor. It is characterized by an emitter or a source-grounded transistor connected to the constant current source via an emitter or source, a resistor, a frequency band control circuit, and a differential pair of cascode transistors.
- a signal path switching unit is connected to a common emitter or a source of a transistor that forms a differential pair, and a collector or a drain is connected to a common emitter or a source of the transistor, respectively.
- a collector or a drain is connected to a common emitter or a source of the transistor, respectively.
- the collector or the drain is commonly connected to the emitter or the source of the cascode transistor, respectively, and the emitter or the source is connected to the collector or the drain of the transistor and the resistor, respectively, and A configuration having a cascade transistor in which a base or a gate is commonly connected to a bias power supply may be adopted.
- an emitter or source-grounded transistor grounded through a resistor including zero ohms, a transistor, a resistor, a frequency band control circuit, and a power scat transistor are connected to the emitter or the source via a resistor, respectively.
- a differential pair configuration of a constant current source, a transistor, a resistor, a frequency band control circuit, and a cascode transistor connected to a connection point between an emitter or a source-grounded transistor connected to a source and a resistor may be used.
- each collector or drain is commonly connected to the emitter or source of the cascode transistor, and the emitter or source is connected to the collector or drain of the emitter or source grounded transistor, respectively.
- a configuration having a cascode transistor connected to a resistor and having a base or a gate commonly connected to a bias power supply may be adopted.
- an emitter or a source-grounded transistor having an emitter or a source grounded through a resistor including zero ohms, a resistor, a frequency band control circuit, and a cascode transistor are each fixed via a resistor.
- a differential pair configuration of an emitter or source grounded transistor connected to the current source or emitter, a resistor, a frequency band control circuit, and a cascode transistor may be used.
- the collector or the drain is connected in common to the emitter or the source of the power transistor of the differential pair configuration, and the emitter or the source is respectively connected to the emitter or the source of the differential pair configuration.
- a cascade transistor having a differential pair configuration in which the collector or drain of the common source transistor is connected to a differential pair resistor and the base or gate is commonly connected to a bias power supply. Is also good.
- the frequency band control units may be frequency band control units having different cutoff orders.
- control voltage that enables a plurality of signal transmission paths to operate simultaneously may be applied to the control voltage applied to the frequency band variable circuit.
- the frequency band variable circuits may be connected in cascade to control each band independently.
- the frequency band control unit is a frequency band control unit having a different cutoff order, and a control voltage applied to the frequency band variable circuit is applied so that a plurality of signal transmission paths can operate simultaneously. You may do it.
- frequency band control units may be frequency band control units having different cutoff orders, and frequency band variable circuits may be connected in cascade to control each band independently.
- the frequency band control unit is a frequency band control unit having a different cutoff order, and a frequency band variable circuit is cascaded, and a plurality of signal transmission paths are simultaneously connected to a control voltage applied to the frequency band variable circuit.
- an active second-order low-pass filter is provided. This makes it possible to configure a filter circuit, a second-order high-pass filter circuit, a second-order band-pass filter circuit, and a resonance circuit, which has the effect of making the cutoff frequency and resonance frequency variable over a wide range.
- the use of the input capacitance of the transistor whose collector and emitter are grounded at a high frequency eliminates the need for using a capacitor of an individual component. Since this can be easily realized by an integrated circuit, the size of the system can be reduced and the performance of the system can be greatly improved.
- FIGS. 1 (a) and 1 (b) are diagrams for explaining the first embodiment of the portion relating to the active filter in the present invention
- FIGS. 2 (a) and 2 (b) are FIGS. 3A and 3B are diagrams for explaining a second mode of a portion related to the active filter in the present invention
- FIGS. 3A and 3B are diagrams illustrating the active filter in the present invention, respectively.
- FIGS. 4A and 4B are diagrams for explaining a third embodiment of the portion
- FIGS. 4A and 4B are diagrams for explaining a fourth embodiment of the portion relating to the active filter in the present invention.
- FIGS. 5 (a) and 5 (b) are diagrams for explaining the fifth embodiment of the part relating to the active filter in the present invention
- FIGS. 6 (a) and 6 (a) (b) is a diagram for explaining the sixth embodiment of the portion related to the active filter in the present invention
- FIGS. 7 (a) and (b) are the active type filters of the present invention, respectively.
- the seventh state of the part of Phil FIGS. 8 (a) and 8 (b) are diagrams for explaining an eighth aspect of the portion relating to the active filter in the present invention
- FIGS. FIG. 9 is a diagram for explaining a first embodiment of a portion relating to the active filter circuit of the present invention
- FIG. 10 is a diagram illustrating a portion relating to the active filter circuit of the present invention.
- FIG. 11 is a diagram for explaining a second embodiment of the present invention, and FIG. 11 is a diagram for explaining a third embodiment of a portion related to the active filter circuit of the present invention.
- FIG. 12 is a diagram for explaining a fourth embodiment of the portion relating to the active filter circuit of the present invention, and FIG. 13 is a fifth embodiment of the portion relating to the active filter circuit of the present invention.
- FIG. 14 is a diagram for explaining the embodiment, FIG. 14 is a diagram showing the original configuration of the circuit of FIG. 13, FIG. 15 is an active filter circuit of the present invention;
- FIG. 16 is a diagram for explaining a sixth embodiment of such a portion, and FIG.
- FIG. 16 is a diagram for explaining a seventh embodiment of a portion relating to an active filter circuit of the present invention.
- G.17 is a diagram for explaining an eighth embodiment of the portion relating to the active filter circuit of the present invention
- FI G.18 is a diagram which relates to the active filter circuit of the present invention.
- FIG. 19 is a diagram for explaining a ninth embodiment of the portion, and FIG. 19 is a diagram for explaining a tenth embodiment of the portion relating to the active filter circuit of the present invention.
- FIG. 20 is a diagram for explaining a first embodiment of the portion relating to the active filter circuit of the present invention, and
- FIG. 21 is a diagram illustrating the first embodiment of the portion relating to the active filter circuit of the present invention.
- FIG. 22 is a diagram for explaining an embodiment, and FIG. 22 is a diagram for explaining a thirteenth embodiment of a portion related to an active filter circuit of the present invention.
- Fig. 24 is a diagram showing an equivalent circuit for obtaining impedance in anticipation of the emitter,
- Fig. 24 is a diagram showing a first simulation result, and
- Fig. 25 is a diagram showing a second simulation result.
- FIG. 26 is a block diagram for explaining an aspect of a portion related to the frequency band variable filter circuit of the present invention.
- FIG. 27 is a first embodiment of the frequency band variable filter circuit of the present invention.
- FIG. 28 is a block diagram of a portion according to a second embodiment of the frequency band variable filter circuit of the present invention, and
- FIG. Fig. 30 is a block diagram of a portion of a frequency band variable filter circuit according to a third embodiment of the present invention;
- FIG. 30 is a block diagram of a portion of the frequency band variable filter circuit of the present invention according to a fourth embodiment;
- FIG. 31 is a block diagram of a part of the fifth embodiment of the frequency band variable filter circuit of the present invention, and FIG.
- FIG. 32 is a block diagram of the frequency band variable filter circuit of the present invention.
- FIG. 33 is a block diagram of a portion according to the sixth embodiment, FIG. 33 is a block diagram of a portion of the frequency band variable filter circuit according to the seventh embodiment of the present invention, and
- FIG. 34 is a block diagram of the present invention.
- FIG. 35 is a block diagram of a portion of the frequency band variable filter circuit according to the eighth embodiment of the present invention, and FIG. 35 is a block diagram of a portion of the frequency band variable filter circuit of the ninth embodiment of the present invention.
- FI G. 36 is the frequency band variable filter of the present invention.
- FIG. 37 is a block diagram of a portion related to the tenth embodiment of the evening circuit, and FIG.
- FIG. 38 is a diagram for explaining frequency characteristics as an embodiment.
- FIG. 38 is a circuit configuration diagram of a first embodiment of a frequency band variable filter circuit of the present invention
- FIG. ), (b) and (c) are diagrams for explaining the frequency characteristics of the frequency band variable filter circuit according to the first and second embodiments of the present invention.
- FIG. 38 is a diagram showing a specific configuration example of a cascade connection of the embodiment shown in 38
- FIG. 41 is a diagram showing a specific example of a second embodiment of the frequency band variable filter circuit of the present invention
- FIG. 42 is a diagram showing an example of a result of a simulation by SPI CE.
- FIG. 43 is a diagram showing a fifth embodiment of the frequency band variable filter circuit of the present invention.
- FIG. 44 is a diagram showing a specific example, and FIG. 44 is a diagram showing an example of a result obtained by simulating the circuit shown in FIG. 43 by SPI CE, and FIG. This is a specific example of the 10th embodiment of the frequency band variable filter circuit.
- Fig. 47 is a diagram showing an example of the result obtained by simulating the circuit shown in G.45 by SPICE.
- FI G.47 (a) and (b) are diagrams each showing a configuration example of the current source.
- FIG. 48 is a diagram showing a configuration example of an optical signal receiving unit in an optical communication system
- FIG. 49 is a diagram showing an example of a conventional active filter circuit
- FIG. 5 is a diagram showing a first conventional example related to a frequency band variable filter circuit
- FIG. 51 is a diagram showing a result of simulation by SPICE
- FIG. 52 is a diagram showing a frequency band variable filter circuit.
- FIG. 9 is a diagram showing a second conventional example.
- FIG. 1 is a diagram for explaining a first embodiment of the present invention
- FIG. 1 (a) is a diagram showing a configuration of a second-order low-pass filter circuit
- FIG. 1 (b) is a diagram. It is a figure showing the equivalent circuit.
- T1 is a transistor that forms an inductance
- 13 ⁇ 41 and 13 ⁇ 42 are resistors
- C1 is a capacitor.
- the current flowing into the resistor R2 and the capacitor C1 is input, and the current flowing out of the collector of the transistor T1 is output, and the current transfer function of the circuit shown in FIG. Determine using G.23.
- FIG. 23 is an illustration of an equivalent circuit for obtaining an impedance in anticipation of the emission of the transistor T1 in FIG. 1 (a).
- R 1 is the same resistance as R 1 in FI G. 1 (a)
- Z 7 ⁇ is the base resistor in the 7 ⁇ equivalent circuit of the transistor. It is the impedance of the sunset.
- g m is the transconductance of the transistor
- V is the terminal voltage of the Z 7 ⁇
- g m ⁇ V is the collector current source transistor.
- Is the emitter current amplification factor, and R is the resistance value of the resistor R1.
- Rn the resistance value of the resistor RN Rn, the capacitance of the capacitor CN and C n.
- Equation (1) R is set to 1 / g m , and usually holds 1> 1 // 3.
- equation (2) By applying, the following equation is approximately established in the frequency range of 1 >> ( ⁇ / ⁇ ) 2 .
- the equivalent element forming Z E in FIG. 23 is the equivalent inductance of the value given by the following equation.
- the circuit shown in FIG. 1 (a) is a low-pass filter circuit having a secondary cut-off characteristic using current as input and output.
- the filter circuit of the first aspect of the present invention by realizing the characteristics of the coil by the transistor, the LCR low band having the second-order cut-off characteristics using current as input / output is provided.
- the filter circuit can be configured without using the individual component coil (L), which has the advantage that a secondary low-pass filter circuit that inputs and outputs current can be very easily integrated.
- the equivalent circuits shown in FIGS. 2 (b) to 8 (b) used in the following description are the circuits shown in FIGS. 2 (a) to 8 (a), respectively.
- the transistor is replaced with an equivalent inductance.
- FIG. 2 is a diagram for explaining the second embodiment of the present invention.
- FIG. 2A is a diagram illustrating a configuration of a second-order low-pass filter circuit
- FIG. 2B is a diagram illustrating an equivalent circuit thereof.
- T7 is a transistor that forms an inductance
- R10 and R11 are resistors
- C5 is a capacitor
- CCS3 is a constant current source.
- the circuit shown in FIG. 2 (a) is a low-pass filter circuit having a second-order cutoff characteristic using voltage as input and output.
- the filter circuit according to the second aspect of the present invention similarly to the first aspect, by realizing the characteristic of the coil by the transistor, the secondary cutoff using the voltage as the input / output
- An LCR low-pass filter circuit with characteristics can be configured without using individual component coils, which makes it possible to very easily integrate a secondary low-pass filter circuit that uses voltage as input and output.
- the collector of the transistor T7 is connected to the power supply V CC.
- a second-order low-pass filter circuit is possible even if impedance is interposed.
- the equivalent inductance is no longer R! OZWT, so the band that can be used as a second-order low-pass filter is narrow.
- FIG. 3 is a diagram for explaining a third embodiment of the present invention
- FIG. 3 (a) is a diagram showing a configuration of a secondary high-pass filter circuit.
- (b) is a diagram showing an equivalent circuit thereof.
- T 2 is a transistor that forms an inductance
- R 3 and R 4 are resistors
- C 2 is a capacitor.
- the circuit shown in FIG. 3 (a) is a high-pass filter circuit having a secondary cut-off characteristic using current as input and output.
- the LCR high-pass filter circuit having the secondary cut-off characteristics with current input / output is provided. This is advantageous in that a high-pass filter circuit using current as input and output can be very easily integrated into a circuit.
- a certain impedance may be interposed between the collector of the transistor T2 and the power supply or GND, but it should be noted that the usable band is narrowed.
- FIG. 4 is a diagram for explaining a fourth embodiment of the present invention
- FIG. 4 (a) is a diagram showing a configuration of a second-order high-pass filter circuit.
- T 8 forms an inductance In Rungis, R12 and R13 are resistors, C6 is a capacitor, and CCS4 is a constant current source.
- circuit shown in FIG. 4 (a) is a high-pass filter circuit with secondary cut-off characteristics using voltage as input and output.
- the LCR high-pass filter circuit having a secondary cut-off characteristic using voltage as input / output.
- the LCR high-pass filter circuit can be configured without using individual component coils, and this has the advantage that a high-frequency filter circuit that inputs and outputs voltage can be very easily integrated.
- a certain impedance may be interposed between the collector of the transistor T8 and the power supply V CC, but it should be noted that the usable band is narrowed.
- FI G. 5 is a diagram for explaining a fifth aspect of the present invention
- FI G. 5 (a) is a diagram showing a configuration of a second-order band-fill ⁇ evening circuit
- FI G. 5 (b) is a diagram showing an equivalent circuit thereof.
- T3 is a transistor that forms an inductance
- R5 and R6 are resistors
- C3 is a capacitor.
- the circuit shown in FIG. 5 (a) is a band-pass filter circuit having a second-order cutoff characteristic that inputs and outputs currents.
- the LCR bandpass filter circuit having the secondary cut-off characteristic with the current input / output can be individually realized. It can be configured without using component coils, and this has the advantage that a second-order bandpass filter circuit that inputs and outputs current can be very easily integrated.
- a certain impedance may be interposed between the collector of the transistor T3 and the power supply V CC, but it should be noted that the usable band is narrowed.
- FIG. 6 is a diagram for explaining a sixth embodiment of the present invention
- FIG. 6 (a) is a diagram showing a configuration of a secondary bandpass filter circuit
- FIG. 6 (b) is a diagram showing an equivalent circuit thereof.
- T 9 is the inductance forming inductance.
- R14 and R15 are resistors
- C7 is a capacitor
- CCS5 is a constant current source.
- the circuit shown in FIG. 6 (a) is a band-pass filter having secondary cut-off characteristics using voltage as input and output.
- the LCR band filter circuit having a second-order cut-off characteristic using voltage as input / output.
- the LCR band filter circuit having a second-order cut-off characteristic using voltage as input / output.
- a certain impedance may be interposed between the collector of the transistor T9 and the power supply V CC, but it should be noted that the usable band is narrowed.
- FIG. 7 is a diagram for explaining a seventh embodiment of the present invention
- FIG. 7 (a) is a diagram showing a circuit constituting a resonator
- FIG. 7 (b) is a diagram It is a figure showing the equivalent circuit.
- T 4 is a transistor that forms inductance
- R 7 is a resistor
- C 4 is a capacitor.
- circuit shown in FIG. 7 (a) is a resonator that inputs current and outputs voltage.
- the filter circuit of the seventh aspect of the present invention by realizing the characteristics of the coil with the transistor, the current input-voltage output LCR resonator can be used as the coil of the individual component. This has the advantage that a current input-voltage output resonator can be very easily integrated into an integrated circuit.
- a certain impedance may be interposed between the collector of the transistor T4 and the power supply V CC, but it should be noted that the usable band is narrowed.
- FIG. 8 is a diagram for explaining an eighth embodiment of the present invention
- FIG. 8 (a) is a diagram showing a circuit constituting a resonator
- FIG. It is a figure showing an equivalent circuit.
- T 10 is a transistor that forms an inductance
- R 16 is a resistor
- C 8 is a capacitor
- CCS 6 is a constant current source. It is.
- the circuit shown in FIG. 8 (a) is a resonator in which a voltage is input and a current is output, contrary to the resonator circuit shown in FIG. 7 (a).
- the voltage-input / current-output LCR resonator can be used as the coil of the individual component.
- the resonator can be configured without using it, and this has the advantage that the resonator can be very easily integrated.
- FIG. 9 is a diagram for explaining a first embodiment of a portion related to the active filter circuit of the present invention.
- T5 is an input transistor
- T6 is an output transistor
- R8 and R9 are resistors.
- the input terminal of the FI G.1 (a), FI G.3 (a), or FI G.5 (a) circuit is connected to the collector of the transistor T5, and FI is connected to the emitter of the transistor T6.
- the output terminal of the circuit of G.1 (a) or FI G.3 (a) or FI G.5 (a) is connected.
- the directions of I in and I out are ignored,
- a second-order low-pass filter circuit, a second-order high-pass filter circuit, and a second-order band-pass filter circuit can be represented by the following current transfer function. Can be easily realized by a practical circuit by converting to a voltage transfer function, which can greatly improve the performance of systems such as optical communication systems and reduce the size of the system. There is.
- FIG. 10 is a diagram for explaining a second embodiment of the portion relating to the active filter circuit of the present invention.
- T 5 is an input transistor
- T 4 is Transistors forming inductance
- R8 and R7 are resistors
- C4 is a capacitor.
- the circuit shown in FIG. 10 is obtained by connecting the input terminal of the circuit shown in FIG. 7 (a) to the collector of the transistor T5.
- the resonance circuit represented by the transfer impedance equation (22) can be converted from a transfer function to a voltage transfer function as described above.
- the above-described resonance circuit can be easily realized by a practical circuit.
- FIG. 11 is a diagram for explaining a third embodiment of the active filter circuit of the present invention.
- T 10 is a transistor forming inductance and T 11 is a transistor.
- R 16 and 17 are resistors
- C 8 is a capacitor
- CCS 6 is a constant current source.
- the transmission admittance of the resonance circuit in the above-mentioned eighth aspect of the present invention is expressed by the following equation (22). It can be converted to a function, which makes it possible to easily realize the above-described resonance circuit with a practical circuit.
- FIG. 12 is a diagram for explaining the fourth embodiment of the active filter circuit of the present invention.
- T5a and T5b denote input transistor circuits and T6 a and T6b are output transistors, R8a, R8b, R9a and R9b are resistors, and CCS1a, CCS1b and CCS2 are constant current sources.
- the input terminals of the circuit shown in FIG. 1 (a), FIG. 3 (a), or FIG. 5 (a) are connected to the collectors of the transistors T5a and T5b.
- the output terminals of the circuits shown in Fig. 1 (a), Fig. 3 (a), or Fig. 5 (a) are connected to the emitter of 6b, respectively.
- the circuit shown in FIG. 1 (a), FIG. 3 (a), or FIG. 5 (a) are connected to the emitter of 6b, respectively.
- the collector currents of the transistor T5a and the transistor T5b also have the same amplitude and opposite phases, and the collector voltage Vout of the transistor T6a and the collector voltage Vout * of the transistor T6b have the same amplitude and opposite phases. Therefore,
- the circuit shown in FIG. 12 converts the current transfer function into a voltage transfer function in the same manner as the circuit shown in FIG. Since the second-order low-pass filter circuit, second-order high-pass filter circuit, and second-order band filter circuit described in Sections 3 and FI G.5 can be easily realized with practical circuits, optical communication systems, etc. This has the effect of greatly improving the performance of the amplifier installed in the system and reducing the size of the system.
- the circuit shown in FIG. 12 uses the bases of the transistors T5a and T5b as input terminals and the collectors of the transistors T6a and T6b as output terminals as described above. If a balanced filter circuit can be configured, and the base of the transistor T5a or T5b is used as the input terminal and the collector of the transistor T6a or T6b is used as the output terminal, balanced input-unbalance An output fill circuit can be configured.
- a balanced output filter circuit can be configured, and the transistor T5a or transistor If one of the bases of the transistor T5b is used as an input terminal and the other base is alternately grounded, and the collector of the transistor T6a or the transistor T6b is used as the output terminal, unbalance-unbalance will occur.
- a balanced filter circuit can be configured.
- the constant current sources CCS 1 a and CCS 1 b supply a bias current to the output transistor and the transistor that forms the inductance in the black box in the circuit shown in FI G. 12. This is to expand the dynamic range of the circuit shown in G.12.
- FIG. 13 is a diagram for explaining the fifth embodiment of the active filter circuit of the present invention.
- T4a and T4b form the inductance of the transistor
- R8a, R8b, R7a and R7b are resistors
- C4 ' is a capacitor
- CCS la, CCS 1b and CCS 2 is a constant current source.
- the circuit shown in FIG. 13 is a circuit in which the input terminals of the circuit of FIG. 7 are connected to the collectors of the input transistors T 5 a and T 5 b.
- the circuit shown in FIG. 14 is the same as that shown in FIG. 14, considering that the input transistors T 5 a and T 5 b are a differential amplifier driven by the constant current source CCS 2. Circuits of the capacitors C 4 a and C 4 b in 14 are circuit-converted.
- the AC components of the collector voltage between the input transistor T5a and the input transistor T5b in FIG. 14 become equal in phase and opposite in phase, and flow through the capacitor C4a and the capacitor C4b.
- the AC component also has the same amplitude and opposite phase. Therefore, no current flows between the connection point of the capacitors C4a and C4b and the ground, and the current distribution of the circuit does not change even if this connection point is not connected to the ground.
- the portions of capacitors C 4 a and C 4 b in 14 can be replaced with capacitors C 4 ′ in FIG. 13. Here, capacitors C 4 a and C 4 b in FI G. If the sum of the quantities is C 4.
- the capacitance of the capacitor C 4 ′ in FIG. 13 is C 42, then the voltage transfer function of the circuit shown in FIG. 13 and the voltage transfer function of the circuit shown in FIG.
- the transmission impedance will have the same frequency characteristics.
- the resonator described in FIG. 7 can be easily realized with a practical circuit, particularly an integrated circuit.
- the circuit shown in Fig. 13 is also used as a balanced filter circuit, a balanced-unbalanced filter circuit, an unbalanced-balanced filter circuit, and an unbalanced filter circuit, like the circuit shown in Fig. 12 It is possible.
- the constant current sources CCS 1a and CCS 1b are for expanding the dynamic range of the circuit shown in FIG.
- FIG. 15 is a diagram for explaining a sixth embodiment of a portion related to the active filter circuit of the present invention.
- T 7 a and T 7 b are R10a
- R10b and R1 ⁇ are resistors
- C5 ' is a capacitor
- CCS3a and CCS3b are transistors that serve as both an input transistor and a transistor that forms an inductance. It is a constant current source.
- the circuit shown in FIG. 15 uses two circuits shown in FIG. 2 and applies a voltage of opposite phase with equal amplitude to the base of each transistor, and emits the emitter of each transistor. This is a circuit conversion of the parallel circuit part of the capacitor C5 and the resistor R11 in FIG. 2 using the fact that the evening potential has the same amplitude and the opposite phase.
- the capacitance of the capacitor C 5 ′ is set to 1 Z2 of the capacitance of the capacitor C 5 and the resistance of the resistor R 11 ′ is twice the resistance of the resistor R 11, the FI G. 15 can be obtained.
- the voltage transfer function of the circuit shown and the voltage transfer function of the circuit shown in FIG. 2 have the same frequency characteristics.
- a secondary low-pass filter circuit using no coil can be easily realized by a practical circuit such as an integrated circuit.
- the performance of the amplifier provided in a communication system is greatly improved, and the effect of miniaturizing the system is obtained.
- FIG. 16 is a diagram for explaining a seventh embodiment of a portion related to the active filter circuit of the present invention.
- T 8 a and T 8 b are Transistors forming inductance
- C6a and C6b are capacitors
- CCS4a and CCS4b are constant current sources.
- the circuit shown in FIG. 16 uses two of the circuits shown in FIG. 4 (a) and performs circuit conversion similar to that described above in FIG.
- the circuit configuration shown in FIG. 16 makes it possible to easily realize the secondary high-frequency filter circuit using voltage as input and output shown in FIG. 4 with a practical circuit. It is.
- a secondary high-pass filter circuit that does not use a coil can be easily realized by a practical circuit such as an integrated circuit, so that the performance of an amplifier provided in an optical communication system and the like can be greatly improved, and the size of the system can be reduced. This has the effect of making it possible.
- FIG. 17 is a diagram for explaining the eighth embodiment of the portion relating to the active filter circuit in the present invention.
- T 9 a and T 9 b are Transistors that form inductance
- R14a, R14b, R15a, and R15b are resistors
- CCS5a and CCS5b are constant current sources.
- the circuit shown in FIG. 17 is obtained by performing the same circuit conversion as described above in FIG. 14 using two circuits shown in FIG.
- the capacitance of the capacitor C 7 ′ in this FIG. 17 is set to 1 / th of the capacitance of the capacitor C 7 in FIG. 6, the voltage transfer function of the circuit shown in FIG. The frequency characteristics of the voltage transfer function of the circuit shown in Fig. 6 are the same.
- circuit configuration shown in FIG. 17 makes it possible to easily realize the secondary bandpass filter circuit shown in FIG. 17
- a secondary bandpass filter circuit that does not use a coil can be easily realized by a practical circuit such as an integrated circuit.
- the performance of the amplifier provided in the system etc. is greatly improved, and the effect of miniaturization of the system is achieved. is there.
- FIG. 18 is a diagram for explaining a ninth embodiment of a portion related to the active filter circuit of the present invention.
- T 5 denotes an input transistor
- T 1 denotes an input transistor.
- T12 is a transistor that is connected to the base of T1
- a transistor is a transistor
- T6 is an output transistor
- R8, R2, and R9 are resistors
- C1 is a capacitor
- CCS 1 is a constant current source
- VCS 1 is a variable current source that supplies an emitter current of the transistor T 12.
- the circuit shown in FIG. 18 is equivalent to the circuit shown in FIG. 9 using the circuit shown in FIG. 1 in the black box in the circuit shown in FIG. 9.
- the resistor R 1 in 1, in FI G. 1 8 are those substituted with preparative Rungis evening T 1 2 of e Mi jitter resistance r e.
- the circuit shown in FIG. 18 allows the resistance R 1, which was a fixed resistance value in the circuit shown in FIG. 1, to be variable by the emitter current of the transistor T 12. become.
- the circuit shown in FIG. 18 uses a variable current source VCS 1 to vary the emitter current of the transistor T 12, so that the low-pass filter has a secondary cut-off characteristic and a variable cut-off frequency.
- VCS 1 variable current source
- Evening circuits can be realized with practical circuits
- a secondary low-pass filter circuit whose cutoff frequency can be varied can be easily realized with a practical circuit, particularly an integrated circuit.
- a low-pass filter circuit whose cut-off frequency band can be controlled can be realized with a single integrated circuit, which further improves the performance of amplifiers provided in optical communication systems and the like, and achieves system downsizing. There is.
- the resistance connected to the base of the transistor that forms the inductance is changed by the resistance of the transistor driven by the variable current source.
- An example is shown in which the resistor is replaced with a resistor r e , but the same replacement can be applied to the third to eighth aspects of the portion relating to the active filter circuit in the present invention. Wear.
- FIG. 19 is a diagram for explaining a tenth embodiment of a portion related to an active filter circuit of the present invention.
- T 13 is a function as an input transistor.
- the circuit shown in FIG. 19 is obtained by replacing the resistor R10 in the circuit shown in FIG. 2 with the emitter resistor of the transistor T13.
- the transistor T13 is an emitter-follower amplifier stage for the signal flow, the AC potential at the base of the transistor T13 becomes equal to the AC potential at the base of the transistor T7. See G. 19
- the frequency characteristics of the circuit are the same as the frequency characteristics of the circuit shown in FIG.
- the circuit shown in FIG. 19 is also a low-pass filter circuit having secondary cutoff characteristics, and its cutoff frequency can be made variable by the current of the variable current source VCS2.
- a second-order low-pass filter circuit capable of changing the cutoff frequency is practically used. Since this circuit can be easily realized with an integrated circuit, particularly an integrated circuit, a low-pass filter circuit capable of controlling a cutoff frequency band can be realized with one integrated circuit, thereby further improving the performance of an amplifier provided in an optical communication system or the like. This has the effect of improving the size and miniaturizing the system. Note that FI G.18 and FI G.19 show single-input / single-output circuits, but the above replacement with a variable resistor also applies to differential amplifier circuits. be able to.
- FIG. 20 is a diagram for explaining a first embodiment of a portion related to an active filter circuit of the present invention.
- T 5 is an input transistor
- T 1 Is a transistor forming an inductance
- T6 is an output transistor
- T14 is a transistor forming a capacitor
- R8, R1, R9 and R2 are resistors
- C9 is an emitter of the transistor T14.
- CCS 1 is a constant current source that expands the dynamic range of the circuit
- VCS 3 is a variable current source that makes the emitter current of the transistor T 14 variable.
- the circuit shown in FIG. 20 uses the circuit shown in FIG. 1 as the black box of the circuit shown in FIG. 9 and replaces the capacitor C 1 in FIG. In FIG. 20, this is replaced by the input capacitance of the transistor T14. Therefore, the frequency characteristics of the circuit shown in FIG. 20 are similar to the frequency characteristics given by equation (5), and the circuit shown in FIG. It becomes the area fill circuit.
- the transistor T 14 has the collector and the emitter grounded in an AC manner, so that the input capacitance of the transistor T 14 is C d + C JE + C JC .
- the input capacitance of the transistor T14 can be varied almost in proportion to the current of the variable current source VCS3, and the second-order low-pass filter circuit shown in FIG. It can be made variable by the current of the source VCS3.
- the capacitance of the capacitor is realized by the input capacitance due to the high-frequency grounding of the transistor. Since a second-order low-pass filter circuit with variable cutoff frequency can be easily realized with practical circuits, especially integrated circuits, a low-pass filter circuit with controllable cutoff frequency band can be realized with a single integrated circuit. As a result, the performance of an amplifier provided in an optical communication system or the like can be further improved, and the size of the system can be reduced.
- the circuit shown in Fig. 20 also shows a single-input / single-output type circuit.
- the replacement of the capacitor with a variable capacitor as described above also applies to a differential amplifier type circuit. Applicable.
- FIG. 21 is a diagram for explaining a 12th embodiment of a portion related to the active filter circuit of the present invention.
- T5a, ⁇ 5b are input transistors
- Tla, Tib are transistors forming inductance
- T6a, T6b are output transistors
- T15a, T15b are variable capacitors.
- Transistors to be formed R8a, R8b, R2 ', Rla, Rib, R9a and R9b are resistors
- CCS2 is a constant current source
- CCSla CCS1b
- VCS 3 is a variable current source that supplies a variable bias current to T15a and T ⁇ 5b.
- the circuit shown in Fig. 21 applies the circuit shown in Fig. 1 in the black box of the circuit shown in Fig. 12 and the capacitor C in Fig. 1
- the capacitor corresponding to 1 is replaced with the input capacitance of the transistor T15a and the transistor T15b.
- the transfer function of the circuit shown in FIG. 21 is the same as the transfer function of the circuit shown in FIG. 1, and the circuit shown in FIG. 21 has a second-order cutoff characteristic. It is a low-pass filter circuit.
- the input capacitance of the transistor T15a and the transistor T15a is determined by the connection point of the emitter of the transistor T15a and the transistor T15b. Since this is a virtual earth, the sum of the capacitances at each transistor is given by C d + C JE + C JC , so the second-order low-pass filter circuit shown in FIG. It can be made variable by the current of the source VCS3.
- a secondary low-pass filter circuit capable of making the cutoff frequency variable can be easily realized by a practical circuit, particularly an integrated circuit. Therefore, a low-pass filter circuit capable of controlling the cut-off frequency band can be realized by one integrated circuit, thereby further improving the performance of an amplifier provided in an optical communication system and the like.
- FIG. 22 is a diagram for explaining a thirteenth embodiment of a portion related to an active filter circuit of the present invention.
- T 5 a and T 5 b are input transistors
- T1a and T1b are transistors that form an inductance
- T16a and T16b are transistors that form a resistor with their emitter resistance
- T6a and T6b are output transistors
- R8a , R 8 b, R 2 ', R la, R lb, R 9 a and R 9 b are resistors
- CCS 2 is a constant current source
- CCS 1 b is a circuit It is a constant current source to expand the dynamic range.
- the transistor T5a—Tla—T6a (the same applies to the suffix b) is obtained by applying the circuit shown in FIG. 1 to the black box of the circuit shown in FIG. Therefore, a low-pass filter circuit with second-order cutoff characteristics is constructed.
- the side of the transistor T5a—T16a-T6a (the same applies to suffixes) is basically a low-pass filter circuit with the first-order cutoff characteristics shown in FIG. 49. The same is true.
- the circuit shown in FIG. 22 is based on the setting of the base bias voltage V2 of the transistor Tla and the transistor T1b, and the base bias voltage V1 of the transistor T16a and the transistor T16b. In addition, it is possible to switch between a second-order low-pass filter circuit and a first-order low-pass filter circuit.
- the circuit shown in FIG. 22 sets the base bias voltage V1 low. And cut off the transistors Ti6a and T16b, and set the base bias voltage V2 high to allow current to flow through the transistors T1a and Tib to reduce the secondary low-pass. A filter circuit is formed. Conversely, if the transistors T1a and Tib are cut off and current is supplied to the transistors T16a and T16b, a first-order low-pass filter circuit is obtained.
- the same integrated circuit in addition to the above-described effects of the secondary low-pass filter circuit, the same integrated circuit can have different functions. This has the advantage of increased flexibility in circuit design.
- the resistor R 1 a replacing the R 1 b at r e of the transistor is supplied with current from the variable current source also Oh Rui capacitor C, and C 1 "variable It is also possible to replace with a capacity that allows for the base of the transistor supplied with current from the current source.
- a circuit in which the primary low-pass filter circuit and the secondary low-pass filter circuit are combined and used by switching is described as an example, but the combined filter circuit is limited to the above.
- a combination of filter circuits having arbitrary characteristics is possible, and the present invention is not limited to the differential amplifier type.
- FIG. 24 shows that the resistor R 1 in the circuit shown in FIG. 2 shows the characteristics of the high frequency fill evening circuit obtained by substituting r e of the transistor to be supplied with current from the variable current source, as shown in FI G. 24, by increasing the current of the variable current source yuku If (since r e is small) it can be seen that the cut-off frequency increases.
- FI G.25 is a feature of the low-pass filter circuit shown in FI G.21. As shown in Fig. 25, when the emitter current of a transistor that forms a variable capacitor is increased (because C d increases in proportion), the cutoff frequency may decrease. I understand.
- the active filter circuit using a bipolar transistor which is usually called a transistor
- a bipolar transistor which is usually called a transistor
- an electric field effect circuit is used.
- a similar circuit can be formed by using a transistor.
- the g m is a relatively low damage, the characteristics of the fill evening circuit is undeniable that inferior to the case of using the evening transistors, very easily digital circuit There is an advantage that a filter circuit can be formed on the same chip as the above.
- FIG. 26 is a diagram showing an aspect of a portion related to the frequency band variable filter circuit in the present invention.
- 21 is a signal path switching unit
- 51, 52,. , 5N are frequency band controllers
- 401 is a cascode transistor
- 81 is a resistor
- VB1 is a bias power supply
- a, b, ..., n are signal transmission paths.
- the frequency band variable filter circuit used in the signal receiving section of the optical communication system shown in FIG. 26 changes the control voltage to be applied, and transmits signal transmission paths a, b, and , N, and signal transmission paths a, b,..., N are provided in frequency band control sections 51, 52,. N and Emmits
- the cascode transistor 401 is connected to the signal path switching unit 21 via the frequency band control units 51, 52,..., 5N.
- the signal path switching unit 21 is connected to an emitter grounding transistor 101 which grounds the emitter via a resistor 91. , 20N connected to the collector of the emitter-grounded transistor 101.
- the frequency band control circuits 501, 52,..., 5N connect the collectors of the transistors 201, 202,. , 50N, and resistors 302,..., 3ON having different impedances R2,..., RN connected to the collectors of the transistors 202,.
- the cascode transistor 401 is connected to the emitter of the transistor 101 via the collector of the transistor 101 and the resistors 302,..., 3ON. Configure to connect to 0 N collector. Then, a signal voltage Vin is applied to the base of the emitter-grounded transistor 101, and the control voltages VI, V are applied to the bases of the transistors 201, 202,. 2,.., VN are applied, the transmission path of the collector signal current of the emitter-grounded transistor 101 is switched, and the frequency band variable circuit 501, 500, , 5 ON should be controlled.
- an emitter grounded transistor 101 grounded via a resistor 901 and a transistor 201, , 20 N, resistors 30 2,..., 30 N, frequency band control circuits 50 1, 50 2,. 1 is connected to emitter via resistors 901a and 901b, respectively. Connection of emitter ground transistor 10la, 10lb and resistors 901a and 901b is connected.
- a differential pair consisting of 0 Na, 30 Nb, frequency band control circuits 501, 502,... 5 ON, and cascode transistors 401 a, 401 b may be used. .
- the signal path switching unit 21 is connected to an emitter grounded transistor 101 grounded via a resistor 91 and to resistors 90 2,. It consists of grounded emitter transistors 102,..., And 10N.
- the signal voltage Vin and the control voltage V are applied to the bases of the emitter grounded transistors 101, 102,..., And 100N to apply V2,.
- the signal path may be switched to control the frequency band control circuits 501, 502,..., 5 ON.
- the emitter grounded transistors 101, 102,..., 1 ON, the resistors 300,. , 50 N and the cascode transistor 401 are connected to the resistors 901a, 902a, ⁇ , 90Na and 901b, 902, respectively.
- 90 Nb via an emitter connected to a constant current source 70 1 via an emitter emitter transistor 1 ⁇ 1 a, 101 b, 102 a, 102 b , ⁇ , 10 N a, 10 Nb, resistors 30 2 a, 30 2 b, ⁇ ⁇ , 3 ON a, 3 O Nb, and frequency band control circuits 50 1, 50 2,. , 5 ON and a differential pair of cascode transistors 401a and 401b.
- the signal path switching constituted by the emitter grounded transistors 101 a, 102 a,..., L ONa and 101 b, 102 b, ⁇ ′, l ONb is performed.
- Unit 21 is composed of transistors 101a, 101b, 102a, 102b, ..., 10Na, lONb, which form a differential pair. Connect to the common emitters of 101 a, 101 b, 102 a, 102 b, ..., 110 Na, and 100 Nb, and connect the emitters to each other. .., 20 N connected in common to transistors 201, 202,..., 20 N and a current source connected to a common emitter of transistors 201, 202,. And
- a common signal is applied to the bases of the transistors 101a, 102a,..., 10Na and 101b, 102b,.
- a voltage V in is applied, and control voltages V 1, V 2,..., VN are applied to respective bases of the transistors 201, 202,.
- the signal path may be switched by setting V2,..., VN to control any of the frequency band control circuits 501, 502,.
- each collector is connected in common to the cascode transistor 401 emitter, and each collector is connected to the transistor collector 201 resistor and resistor 302 ,..., 40 N * and a cascode transistor 401 ′, 402 ′,..., 40 N * whose base is commonly connected to the bias power supply VB 2. .
- an emitter grounded transistor 101 grounded via a resistor 91, and transistors 201, 202,. ., 30 N, the frequency band control circuit 501, 502,..., 50 N, and the cascode transistor 40. , 40 2 ',..., 40 ⁇ ' are respectively connected to resistors 90 1 a,
- Emitter grounded transistor whose emitter is grounded via 91b b Constant current source connected to the junction of 101a, 101b and resistor 90la, 90b ., 20 ⁇ a, 20 Nb, and transistors 30 2 a, 30 2 b,--3 0 N a, 3 O Nb, frequency band control circuits 501, 500,..., 5 ON, and cascode transistors 410 a, 400 b, 0 1 a ', 0 1 b ., 40 ⁇ a ', 40 Nb'.
- each collector is connected to the emitter of the cascode transistor 401 in common, and each emitter is connected to the emitter grounding transistor 10.
- Cascode transistors 40 ⁇ ⁇ , 402 ′,..., 40 N ′ connected to the collector of 1 and resistors 302,..., 3 ON and the base is commonly connected to the bias power supply VB 2. May be provided.
- the emitter grounded transistors 101, 102,..., 10 and N and the resistors 302,. ., 50 N, and the cascode transistors 401 and 401 ′, 402 ′,..., 40 N ′. Respectively, connected to the constant current source 701 via the resistors 901a, 901b, 902a, 902b,..., 90Na, 9ONb , Grounded transistors 101 a, 102 a,..., 10 Na and 101 b,
- the collector is connected to the emitters of the cascode transistors 401a and 401b in common, and the collectors are respectively connected to the collectors. Are connected to the collectors of the emitter-grounded transistors 101a, 101b and the resistances 302a, ...
- a plurality of signal transmission paths are connected to the control voltages V, V2,..., VN applied to the frequency band variable filter circuit.
- a control voltage that enables operation at the same time may be applied.
- the frequency band variable filter circuits are cascaded, and the frequency bands of the respective frequency band variable filter circuits are controlled independently. You may. Further, in the thirteenth method, in the first to tenth methods described above, the control voltages V 1, V 2,... And a cascade connection of frequency band variable filter circuits so that the frequency bands of the respective frequency band variable filter circuits can be controlled independently. In the method, in the above-described first to tenth methods, the frequency band control units (5 to 52,..., 5N) are changed to the frequency band control units (5 to 52) having different cutoff orders. , ⁇ ⁇ , 5 N).
- the frequency band control units (5, 52, ..., 5N) are replaced by frequency band control units (51, 52, ..., 5N) having different cutoff orders.
- a control voltage may be applied to the control voltages V 1, V 2,..., VN applied to the band variable filter circuit so that a plurality of signal transmission paths can operate simultaneously.
- the frequency band control units (51, 52,..., 5N) are controlled by the frequency bands having different cutoff orders.
- the frequency band variable filter circuits are connected in cascade, and the frequency bands of the respective frequency band variable filter circuits are controlled independently. It may be.
- the frequency band control units (51, 52, ⁇ , 5N) are controlled by the frequency bands having different cutoff orders.
- the control unit (51, 52, ..., 5N) multiple signal transmission paths can operate simultaneously for the control voltages V1, V2, ..., VN applied to the frequency band variable filter circuit. It is also possible to cascadely connect frequency band variable filter circuits for applying a control voltage such that the following equation is satisfied, and to independently control the frequency bands of the respective frequency band variable filter circuits.
- the input signal changes the control voltage to be applied to the signal transmission paths a, b,. , N via the signal path switching section 21 and the signal transmission paths a, b,... Connected to the frequency band control sections 51, 52,. , N, and then output from cascode transistor 401
- the control voltage must be changed (the signal transmission paths a, b,..., N through which the input signal passes can be switched, and the frequency band control for the input signal must be performed). Can be.
- the signal path switching section 21 is connected to an emitter grounded emitter 101 via a resistor 901, and an emitter grounded transistor 101, .., 20 N connected to the collector of emitter transistor 101.
- 5N are connected to the collectors of the transistors 201, 202,..., 2 ON, and the frequency band control circuits 501, 502,. , 50N, and resistors 302,..., 30N having different impedances R2,..., RN connected to the collectors of the transistors 202,.
- the cascode transistor 401 connects the emitter to the collector of the emitter-grounded transistor 101 and the transistors 202,..., 2 via resistors 302,. Connect to any of the 0 N collectors.
- the signal voltage Vin is applied to the base of the emitter grounded transistor 101, and the base of each of the transistors 201, 202,. Apply voltages V1, V2,..., VN.
- control voltages VI, V2,..., VN are controlled so that the transmission path of the collector signal current of the emitter-grounded transistor ⁇ 01 1 flows through the signal transmission path.
- Routes a, b,..., And n can be switched to the optimal route with the required variable bandwidth.
- an emitter grounded transistor 10 is obtained by grounding the emitter via the resistor 91. 1, transistors 201, 202,..., 20 N, resistors 302,..., 3 ON, and frequency band control circuits 501, 502,.
- the cascode transistor 401 is connected to an emitter grounded transistor 101a, 101b with the emitter grounded through resistors 90la and 90b, respectively, and the resistor 91a, A current source 70 1 connected to the connection point of 90 1 b and transistors 201 a, 20 1 b, 20 2 a, 20 2 b,..., 20 Na, 20 Nb ., 30Na, 3ONb, frequency band control circuits 501, 502,..., 5ON, cascode transistor 4 0 1 a, b differential pair configuration.
- the input signal Vin and the inverted sign Vin are input to the bases of the emitter grounded transistors 101a and 101b, respectively, and the control signals V1, V2,. Applied to transistors 201 a, 202 a,..., 20 Na and 201 b, 202 b,.
- the collector signal currents of the emitter-grounded transistors 101a and 101b and the transmission path through which the inverted signal flows can be controlled by the signal transmission path. Among them, it is possible to switch to the optimal path having a required frequency band variable width.
- a signal path switching section 21 is connected to an emitter grounded transistor 101 having an emitter grounded via a resistor 91, and a resistor 90 ,..., And 100 N are grounded via the N, 102,.
- the emitter grounded transistors 101, 102,... A signal voltage Vin and control voltages V1, V2,..., VN are applied to each base.
- the emitter-grounded transistors 101, 102,. , 3 ON, frequency band control circuits 501, 502,..., 50N, and cascode transistor 401 are connected to constant current source 701, respectively, by an emitter.
- the input and control signals are connected to the emitter grounded transistors 101a, 102a,..., 1ONa and 101b, 102b,. Are superimposed and applied.
- the emitter grounded transistors 101a, 102a,..., 10Na and 101b, 102b The signal path switching section 21 composed of 10 Nb is connected to the transistors 101 a, 101 b, 102 a, 102 b,. 0 N a, l O Nb and the collector are the common emitters of transistors 101 a, 101 b, 102 a, 102 b,. , 20N, and transistors 201, 202,..., 20N, which are connected to each other and the emitters are connected in common.
- a current source 701 connected to the common emitter of .
- a signal voltage is commonly applied to the bases of the transistors 101a, 101b, 102a, 102b, ..., 100Na, and 100Nb that constitute the differential pair. Apply V in and apply control voltages V 1, V 2,..., VN to the bases of the transistors 201, 202,.
- the collector is connected in common to the emitter of the cascode transistor 411, and the emitter is connected to the transistor 20 in the first method. 1 and the cascade transistors connected to the other signal transmission path resistors 302,..., And 3ON, and the bases are commonly connected to the bias power supply VB2. , 40 N ', the required voltages are set by setting the control voltages VI, V2,..., VN in the same manner as in the first embodiment of the present invention. It is possible to switch to an optimal path having a variable frequency bandwidth.
- the first method is configured as a differential pair of the second method. ., 20 N, 401, 410 ', 402',..., 4 ON 'are configured as a differential pair.
- the control voltages VI, V2,..., VN it is possible to switch to the optimum path having the required frequency bandwidth variable width.
- the collector is connected to the emitter of the cascode transistor 401 in common, and the emitter is connected to the emitter.
- Ground transistor .., 4 ON 'connected to the collector and the resistors 302,..., 30N and the base is commonly connected to the bias power supply VB2. Since the configuration is adopted, as in the case of the third method, by setting the control voltages VI, V2,..., And VN, it is possible to switch to the optimum path having the required frequency bandwidth variable width.
- each transistor is provided in the same manner as the configuration in the third method is replaced with the configuration of the differential pair in the fourth method. Since the circuits of 101, 102,..., 1 ON, 410, 401, 412,,..., 40N ′ are configured as a differential pair, the control voltage VI , V 2,..., VN, it is possible to switch to the optimal path having the required variable frequency bandwidth.
- each collector is commonly connected to an emitter of a cascode transistor 410 a, 401 b, Connect the emitters to the collectors of emitter transistors 101a, b and resistors 302a, 302b, ..., 30Na, 3ONb respectively.
- a cascode transistor whose base is commonly connected to a bias power supply VB 2, 410 a ', 410 b', 402 a ', 402 b', ..., 40 Na ', 4 0 Nb ', the control voltage V and V2,..., VN are set in the same way as in the fifth invention to obtain an optimal path having a required frequency bandwidth variable width. Can be switched.
- a plurality of signal transmission paths are simultaneously connected to the control voltages VI, V2,..., VN. Since a voltage that enables operation is applied, the frequency band control circuits 501, 502,..., 5 can be controlled by the control voltages VI, V2,. Flow through multiple operating transmission paths The frequency band can be controlled by controlling the ratio of the signal currents.
- the frequency band variable circuits are connected in cascade, and each band is controlled independently. Therefore, similarly to the above-described first to tenth methods, the signal path can be switched to the optimal path, and the frequency band of the selected path can be made variable.
- a plurality of signal transmission paths are simultaneously connected to the control voltages VI, V2,.
- a voltage that enables operation is applied, and a frequency band variable circuit is cascaded so that each band is controlled independently, so the signal path is switched to the optimal path and the selected path is
- the frequency band can be controlled and the frequency band can be varied, and a sharper frequency characteristic can be obtained.
- the frequency band control unit (5 to 52,..., 5N) Since the frequency band controllers (51, 52,..., 5N) having different cutoff orders may be used, the frequency band controllers (51, 52,. Can be switched to
- the frequency band control unit (51, 52,..., 5N) Is a frequency band control unit (51, 52,..., 5N) having different cutoff orders, and a plurality of signal transmission paths are simultaneously connected to the control voltages V1, V2,. Since a voltage enabling operation may be applied, the frequency band control section (51, 52,..., 5N) can be switched to a desired cutoff order, and the frequency band control circuit 5 0 1, , 50N without controlling the ratio of the signal current flowing through a plurality of transmission paths operated by the control voltages V1, V2,..., VN. .
- the frequency band control unit (51, 52,..., 5N) Are frequency band controllers (51, 52, ..., 5N) with different cutoff orders, and variable frequency band circuits are connected in cascade to control each band independently.
- switching the frequency band controller (51, 52, ..., 5N) to the desired cutoff order switching the signal path to the optimal path and controlling the frequency band of the selected path.
- the frequency band can be made variable.
- the frequency band control unit (51, 52,- ⁇ , 5N) , And 5N each having a different cutoff order, and multiple signal transmission paths operating simultaneously for the control voltages V 1, V 2,..., VN Since a voltage that can be applied is applied and frequency band variable circuits are cascaded to control each band independently, the frequency band control unit (51, 52, ..., 5N) Can be switched to the desired cutoff order, and the control voltage V1, V2,..., VN can be used without controlling the frequency band control circuits 501, 502,. It is possible to control the ratio of the signal current flowing through a plurality of operating transmission paths, and to switch the signal path to the optimum path, Controls frequency band of the road, can be a frequency band variable.
- FIG. 27 An embodiment of a portion related to the frequency band variable filter circuit of the present invention will be described using FIGS. 27 to 47.
- FIG. 27 An embodiment of a portion related to the frequency band variable filter circuit of the present invention will be described using FIGS. 27 to 47.
- 100 and 200 indicate frequency band variable filter circuits
- 101 , 101 a, 100 b, 102, 102 a, 100 b, 110 N, 100 Na, and 100 Nb are emitter-grounded transistors
- TR 71 and TR 72 are transistors, 3 0 1, 3 O la
- 30 lb, 30 2, 30 2 a, 30 2 b, 30 N, 30 N a, 30 N b are resistors (or diodes), 40 1, 4 0 1 a, 4 0 1 a ', 4 0 1 b, 4 0 1 b', 4 0 2, 4 0 2 a, 4 0 2 a ', 4 0 2 b, 4 0
- FIG. 27 is a diagram showing a configuration of a frequency band variable filter circuit according to the first embodiment of the present invention.
- the signal path switching section 21 in the middle is connected to the emitter grounded transistor 101 with the emitter grounded via the resistor 901 and the collector grounded transistor 101 with the emitter grounded.
- 20N. ., 5N are connected to the collectors of the transistors 201, 202,..., 20N. , 50 N and resistors 30 2,..., 3 ON with different impedances R 2,..., RN connected to the collectors of transistors 202,.
- the cascode transistor 401 is connected to the emitter of the transistor 101 through the collector of the transistor 101 and the resistors 302,. , And 20 N collectors.
- the transmission path of the collector signal current of the emitter-grounded transistor 101 changes according to the control voltages V1, V2,..., VN.
- the frequency band ⁇ ⁇ of the control unit is the same as the conventional circuit because f CNTL (MIN) ⁇ f ⁇ f.
- N ⁇ 1 the frequency band ⁇ of the control unit ⁇ CNTL is
- the frequency band can be made variable over a wide range.
- the frequency band of the amplifier circuit provided in the receiving device of the optical communication system can be adjusted to the optimal frequency band corresponding to the transmission speed of the received signal, thereby effectively amplifying the signal by the amplifier circuit. There is an effect that can be done.
- FIG. 28 is a diagram showing a configuration of a frequency band variable filter circuit according to the second embodiment of the present invention.
- FIG. 28 In the circuit shown in FIG. 28, FIG. In the circuit shown, an emitter grounded transistor 101 grounded via a resistor 901, transistors 201, 202,..., 2 ON, and resistors 302,. ., 50N, and the cascode transistor 401 are connected to the emitter via resistors 901a and 901b, respectively.
- the circuit shown in FIG. 28 uses the collector signal current of the differential pair transistors 101 a and 101 b similarly to the first embodiment described above in FIG.
- the transmission path changes according to the control voltages VI, V2,..., VN.
- the minimum frequency band i CNTL control unit ( M, Runode can be determined by the resistance value R N of the N) resistor RN, appropriately select the resistance RN, the control voltage VI, V 2,.., heat at VN By switching the arrival path, it is possible to make the frequency band variable over a wide range without deteriorating the maximum band.
- the circuit can be easily integrated by making the fill circuit a differential configuration like the differential pair transistors 101a and 101b.
- the frequency band variable filter circuit As described above, according to the frequency band variable filter circuit according to the second embodiment of the present invention, similar to the first embodiment, for example, the frequency band of the amplifier circuit provided in the receiver of the optical communication system is received. Since the frequency band can be adjusted to the optimum frequency band corresponding to the transmission speed of the signal, there is an advantage that the signal amplification processing of the amplifier circuit can be performed effectively.
- FIG. 29 is a diagram showing a configuration of a frequency band variable filter circuit according to a third embodiment of the present invention.
- the signal path switching section 21 in FIG. 26 is connected to an emitter grounded transistor 101, which is grounded via a resistor 901, and resistors 902,.
- FIG. 30 is a diagram showing a configuration of a frequency band variable filter circuit according to a fourth embodiment of the present invention. As shown in FIG. .., 1 ON, the resistors 302,..., 3 ON, and the frequency band control circuits 501, 502,.
- the cascode transistor 401 is connected to a constant current via resistors 901a, 901b, 902a, 902b,..., 90Na, and 90Nb, respectively.
- Emitter grounded transistor connected to emitter 70 1 101 a, 10 lb, 10 2 a, 10 2 b, ⁇ , 10 Na,
- FIG. 31 is a diagram showing a configuration of a frequency band variable filter circuit according to a fifth embodiment of the present invention.
- 10Na and 101b, 102b,..., 10Nb are connected to the signal path switching section 21 by transistors 1 0 1 a, 101b, 102a, 102b,..., 1 ONa, l ONb, and collectors of transistors 101a, 101b, 102a, 102b,.
- Transistors 201, 202,..., 20N connected to the common emitters of ONa, l ONb, and the emitters commonly connected, and transistors 201, 202 ,..., 2 Current source 701 connected to the common emitter of ON.
- the emitter-grounded transistor or the differential pair transistor ′ operated by the control voltages VI, V2,..., VN can be switched.
- the control voltages VI, V2,..., And VN are superimposed on the input voltage Vin, the transistors 101 for signal input in FIG. 2 and the transistors in FIG. It is possible to omit 10 la and 101 b.
- the amplifier circuit provided in the receiver of the optical communication system is provided. Since the frequency band can be adjusted to the optimal frequency band corresponding to the transmission speed of the received signal, there is an advantage that the amplifier circuit can effectively amplify the signal. There is an advantage that the integration can be easily performed. Furthermore, since the control voltage is superimposed on the input voltage and applied, the configuration of the filter circuit can be simplified, thereby providing an advantage that the filter circuit can be more easily integrated. The expansion of the bandwidth control range is the same as in the case of FIG. 27 and FIG. 28.
- FIG. 32 shows a configuration of a frequency band variable filter circuit according to the sixth embodiment of the present invention.
- each collector is commonly connected to the emitter of the cascode transistor 401, and each emitter is connected to the collector of the transistor 201. .., 40 N ′ connected to the resistors 300,..., 3 ON and the base is connected to the bias power supply VB2 in common. I have to.
- FIG. 34 shows the configuration of the frequency band variable filter circuit according to the eighth embodiment of the present invention.
- each collector is commonly connected to the emitter of the cascode transistor 401, and each emitter is connected to the emitter of the emitter transistor 101.
- the emitter is connected to the resistor RN, and the collector is connected to the emitter of the cascode transistor 401.
- the maximum bandwidth is prevented from deteriorating.
- the amplifier circuit provided in the receiving device of the optical communication system has Since the frequency band can be adjusted to the optimal frequency band corresponding to the transmission speed of the received signal, there is the advantage that the signal can be amplified effectively by the amplifier circuit.
- the cascode transistors 40 ⁇ , 402 ′ In addition to the advantage that the integration of the cascode transistors can be easily performed, the cascode transistors 40 ⁇ , 402 ′,. This has the advantage that the bandwidth can be widened.
- FIG. 33, FIG. 34, and FIG. 36 are figures showing the configurations of the seventh, ninth, and tenth embodiments of the present invention (the configuration of such a frequency band variable filter circuit, respectively).
- the emitter is connected to the resistor RN
- the collector is connected to the circuit configuration shown in FIG. 28, FIG. 30, and FIG. 31 in FIG. .., 40 N connected to the emitters of the cascode transistors 401 a and 401 b, the cascode transistors 401 a ', 40 lb', 402 a ', 402 b',. a ', 40Nb' is inserted to avoid the deterioration of the maximum frequency band.
- the cascode transistors 40 4 and 4 02 ',..., 40N' Since the deterioration of the maximum band can be avoided, there is an advantage that the above-mentioned optimum frequency band can be set in a wide range.
- FIG. 37 (a), (b) and (c) all show the present invention.
- FIG. 14 is an explanatory diagram of the operation of the portion related to the frequency band variable filter circuit as the first embodiment.This operation will be described using the circuit shown in FIG. 28 in the second embodiment as an example.
- the circuit configuration shown in FIG. 28 is an example in which two signal transmission paths are provided.
- the transistors 201 a and 202 a are used as the control voltages V 1 and V 2.
- the first embodiment for example, uses the first signal transmission path
- the bandwidth control section of the second signal transmission path is set to a narrow band as shown in Fig.
- control voltages V 1 and V 2 are such that the transistors 201 a and 202 a are turned on and the transistors 20 lb and 202 b are both turned on, as shown in FIG. 37 (c), Since the combined frequency characteristics of the two paths are shown, the control of the frequency band is performed between the minimum band and the maximum band by arbitrarily setting the control voltages V 1 and V 2.
- the second embodiment has been described as an example, but the same applies to the other first embodiment and the third to tenth embodiments.
- FIG. 38 is a diagram for explaining a 12th embodiment of a portion relating to a frequency band variable filter circuit of the present invention.
- the frequency band variable filter circuit according to the 12th embodiment of the present invention, by independently controlling each frequency band, it is possible to set the frequency band and the order of cutoff. If the number of stages in the cascade connection is N, the order of cutoff can be switched between the 1st and Nth orders, so that a filter circuit having different characteristics can be configured in one integrated circuit. This has the effect of minimizing the circuit scale and greatly improving the performance of the amplifier circuit.
- FIG. 40 shows an example of a connection configuration when the above-mentioned frequency band variable filter circuit 100, 200 is cascaded in two stages.
- the signal output of the frequency band variable filter circuit 100 is shown in FIG.
- FIG. 3 is a diagram mainly showing a connection between signal inputs of a frequency band variable filter circuit 200.
- FI G.41 is a diagram showing a specific example of the second embodiment of the portion related to the frequency band variable filter circuit of the present invention shown in FIG. 28, in the case where there are two signal transmission paths. And the signal transmission path is switched by the voltage applied to the control voltages V 1 and V 2.
- the frequency band control circuit of the first signal transmission path is composed of cascode transistors 401a and 401b and differential pair transistors 510a and 501b.
- the frequency band of the first signal transmission path is defined by the cascode transistor 410a, the emitter resistance of 401b, the differential resistance re and the differential pair transistor 501a, 510b the emitter of the transistor. It can be controlled by controlling the current IE that is determined by the diffusion capacitance Cd and flows through the differential pair transistors 501a and 501b.
- the bandwidths ⁇ CNTL, ⁇ CNTL (MAX), and ⁇ CNTL (MIN) of the control unit can be expressed by the following equations, respectively.
- the frequency band control circuit of the second signal transmission path includes a diode connected in series with the cascode transistors 40 la and 40 lb and the emitters of the cascode transistors 401 a and 401 b. It is composed of 302 a, 302 b and differential pair transistors 502 a, 502 b. For this reason, the frequency band of the second signal transmission path is determined by the cascode transistor 40 la, 40 lb emitter resistor re and the cascode transistor.
- Diodes connected in series with the emitter resistors r e of the 4 0 1 a and 4 0 1 b — the output resistors r d of the 3 0 2 a and 3 0 2 b and the differential pair transistors 5 0 2 a,
- T1T region f CNT L, ⁇ CNT L (MAX), and I CNT L (M) N of the control unit can be expressed by the following equations, respectively.
- FIG. 42 is a diagram showing a simulation result of the circuit shown in FIG. 41.
- the solid line is the simulation result of controlling the current of the variable current source 71b when the signal is set to pass through the first signal transmission path, and the variable current source 70
- the frequency band can be made variable.
- the dotted line is a simulation result of controlling the current of the current source 701 b when the signal is set to pass through the second signal transmission path.
- Transistors 501a, 501b By controlling the emitter currents of the transistors 502a, 502b, the frequency band can be made variable.
- the frequency band can be controlled in the frequency range indicated by the solid line and the dotted line.
- FIG. 43 is a specific example of the fifth embodiment of the present invention shown in FIG. 31 and is an example in which there are two signal transmission paths.
- the voltage V is switched by the voltage applied to V2. Note that the frequency band control circuit performs the same operation as that of FIG. 41, and therefore the description is omitted.
- FIG. 44 is a diagram showing a simulation result of the circuit shown in FIG. 43, and shows a result similar to the simulation result shown in FIG.
- FIG. 45 is a specific example of the tenth embodiment of the portion related to the frequency band variable filter circuit of the present invention shown in FIG. 36, and is an example in the case where there are two signal transmission paths.
- the signal transmission path is switched by the control voltage V and the voltage applied to V2.
- the frequency band control circuit of the first signal transmission path is composed of cascode transistors 410a 'and 401b' and differential pair transistors 501a and 501b. Further, the frequency band control circuit of the second signal transmission path is connected in series to the emitters of the cascode transistors 402 a ′ and 402 b ′ and the cascode transistors 402 a ′ and 402 b ′. Resistors 302a and 302b and differential pair transistors 502a and 502b.
- the operation of the frequency band control circuit is the same as that in the case of FIG. 41, and the description thereof is omitted.
- FIGS. 47 (a) and (b) show examples of the configuration of the constant current source and the variable current source used in the embodiment of the present invention.
- the current source using a current mirror circuit is shown in FIG. In the case of 47 (a), the same current as the current flowing through the transistor TR71 can be extracted from lout.
- FI variable current source G. 4 7 (b) is a resistor 7 variable to be able to change the current value taken out from I ou t.
- the use of a field-effect transistor has the advantage that a filter circuit can be formed on the same chip as the digital circuit very easily.
- the filter circuit of the present invention is capable of making the cutoff frequency and the resonance frequency variable, an active secondary low-pass filter circuit, a secondary high-pass filter circuit, a secondary band-pass filter circuit,
- the circuit and the variable frequency band filter circuit can be easily realized by an integrated circuit without using coils and capacitors of individual components, which is useful for improving the performance and miniaturization of the filter circuit. It is suitable for controlling the frequency band of an amplifier that amplifies an attenuated signal used in a system or the like to an optimal value.
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Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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EP94921821A EP0663723B1 (en) | 1993-07-27 | 1994-07-26 | Filter circuit |
DE69426061T DE69426061T2 (de) | 1993-07-27 | 1994-07-26 | Filterschaltung |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
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JP18425693 | 1993-07-27 | ||
JP5/184256 | 1993-07-27 | ||
JP1473394 | 1994-02-09 | ||
JP6/14733 | 1994-02-09 |
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WO1995004401A1 true WO1995004401A1 (fr) | 1995-02-09 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/JP1994/001234 WO1995004401A1 (fr) | 1993-07-27 | 1994-07-26 | Circuit filtrant |
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EP (3) | EP0915565B1 (ja) |
JP (1) | JP3153242B2 (ja) |
DE (3) | DE69426061T2 (ja) |
WO (1) | WO1995004401A1 (ja) |
Families Citing this family (4)
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DE19740193C1 (de) | 1997-09-12 | 1999-03-11 | Siemens Ag | Integriertes Tiefpaßfilter |
DE102004017788B4 (de) | 2004-04-02 | 2008-01-03 | Atmel Germany Gmbh | Oszillator mit abstimmbarer Diffusionskapazität als Schwingkreiskapazität |
US7205836B2 (en) | 2005-05-03 | 2007-04-17 | M/A-Com, Inc. | SiGe differential cascode amplifier with miller effect resonator |
EP3721557B1 (en) * | 2017-12-08 | 2021-08-04 | Telefonaktiebolaget LM Ericsson (publ) | A combined mixer and filter circuitry |
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-
1994
- 1994-07-26 EP EP98120133A patent/EP0915565B1/en not_active Expired - Lifetime
- 1994-07-26 DE DE69426061T patent/DE69426061T2/de not_active Expired - Fee Related
- 1994-07-26 WO PCT/JP1994/001234 patent/WO1995004401A1/ja active IP Right Grant
- 1994-07-26 EP EP94921821A patent/EP0663723B1/en not_active Expired - Lifetime
- 1994-07-26 DE DE1994633184 patent/DE69433184T2/de not_active Expired - Fee Related
- 1994-07-26 JP JP52525394A patent/JP3153242B2/ja not_active Expired - Fee Related
- 1994-07-26 EP EP99114140A patent/EP0951144B1/en not_active Expired - Lifetime
- 1994-07-26 DE DE1994633218 patent/DE69433218T2/de not_active Expired - Fee Related
Patent Citations (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS4936839U (ja) * | 1972-07-03 | 1974-04-01 | ||
JPS49148838U (ja) * | 1973-04-23 | 1974-12-23 | ||
JPS5140737A (ja) * | 1974-10-02 | 1976-04-05 | Hitachi Ltd | Saishoisosuiigatatokaki |
JPS54135137U (ja) * | 1978-03-11 | 1979-09-19 | ||
JPS56166616A (en) * | 1980-05-28 | 1981-12-21 | Fujitsu Ltd | Filter switching circuit |
JPS62160809A (ja) * | 1986-01-10 | 1987-07-16 | Hitachi Ltd | 積分回路 |
JPH0244425U (ja) * | 1988-09-21 | 1990-03-27 | ||
JPH02202212A (ja) * | 1989-01-31 | 1990-08-10 | Canon Inc | 可変抵抗回路 |
JPH0423607A (ja) * | 1990-05-18 | 1992-01-28 | Fujitsu Ltd | フィルタ回路 |
JPH0457979U (ja) * | 1990-09-26 | 1992-05-19 | ||
JPH04150513A (ja) * | 1990-10-15 | 1992-05-25 | Sony Corp | フィルタ回路 |
JPH05140737A (ja) | 1991-11-18 | 1993-06-08 | Ricoh Co Ltd | 窒化鉄磁性薄膜含有積層体とその製法 |
Non-Patent Citations (1)
Title |
---|
See also references of EP0663723A4 * |
Also Published As
Publication number | Publication date |
---|---|
EP0951144B1 (en) | 2003-10-01 |
EP0951144A3 (en) | 2000-03-22 |
EP0663723B1 (en) | 2000-10-04 |
DE69433184T2 (de) | 2004-06-03 |
EP0663723A4 (en) | 1995-11-29 |
DE69433184D1 (de) | 2003-10-30 |
DE69426061D1 (de) | 2000-11-09 |
EP0915565A2 (en) | 1999-05-12 |
EP0663723A1 (en) | 1995-07-19 |
DE69426061T2 (de) | 2001-05-10 |
DE69433218T2 (de) | 2004-07-22 |
EP0951144A2 (en) | 1999-10-20 |
EP0915565A3 (en) | 2000-03-22 |
EP0915565B1 (en) | 2003-09-24 |
JP3153242B2 (ja) | 2001-04-03 |
DE69433218D1 (de) | 2003-11-06 |
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