WO2005112282A1 - 信号処理装置 - Google Patents
信号処理装置 Download PDFInfo
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- WO2005112282A1 WO2005112282A1 PCT/JP2005/007200 JP2005007200W WO2005112282A1 WO 2005112282 A1 WO2005112282 A1 WO 2005112282A1 JP 2005007200 W JP2005007200 W JP 2005007200W WO 2005112282 A1 WO2005112282 A1 WO 2005112282A1
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- 238000012545 processing Methods 0.000 title claims abstract description 132
- 238000001514 detection method Methods 0.000 claims abstract description 26
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- 238000000034 method Methods 0.000 description 10
- 230000007246 mechanism Effects 0.000 description 9
- 230000005540 biological transmission Effects 0.000 description 8
- 230000008859 change Effects 0.000 description 6
- 230000007257 malfunction Effects 0.000 description 5
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- 238000007796 conventional method Methods 0.000 description 4
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/06—Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection
- H04L25/061—Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection providing hard decisions only; arrangements for tracking or suppressing unwanted low frequency components, e.g. removal of dc offset
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
- H03D3/00—Demodulation of angle-, frequency- or phase- modulated oscillations
- H03D3/007—Demodulation of angle-, frequency- or phase- modulated oscillations by converting the oscillations into two quadrature related signals
- H03D3/008—Compensating DC offsets
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/30—Circuits for homodyne or synchrodyne receivers
Definitions
- the present invention relates to a signal processing device applied to a direct conversion receiver or the like, and more particularly, to suppressing a DC offset that dynamically changes according to a surrounding environment, and a signal processing method without dropping a desired signal component.
- the present invention relates to a signal processing device that achieves both transmission and transmission.
- Fig. 1 shows a general configuration example of a conventional direct conversion receiver.
- An RF (Radio Frequency) signal received by an antenna (not shown) is input to an input terminal 1, amplified by a low noise amplifier (hereinafter referred to as LNA) 2, and then branched into two paths. .
- the RF signal branched into two paths is converted into a local signal (hereinafter referred to as an LO signal) input from the local signal input terminals 4a and 4b at down conversion mixers (hereinafter referred to as mixers) 3a and 3b, respectively. It is mixed (multiplied) with t and sin cot, and down-complied.
- LNA low noise amplifier
- the LO signals cos cot and sin cot are signals having a phase difference of 90 degrees from each other, and the frequency of the LO signals cos cot and sin cot is selected to be the same as the carrier frequency of the desired RF signal. Have been. As a result, a baseband signal can be obtained by one down conversion by the mixers 3a and 3b.
- the baseband signals output from the mixers 3a and 3b are divided into variable gain amplifiers 5a, 5b, 7a and 7b, low-pass filters (hereinafter referred to as LPFs) 6a and 6b for channel selection, and analog / It is converted into a digital signal by digital converters (hereinafter referred to as ADCs) 8a and 8b.
- the digital signals converted by the ADCs 8a and 8b are processed by a baseband signal processing unit (BB) 9.
- BB baseband signal processing unit
- the gain control unit (gain setting unit) 10 the LNA2 and the BER (bit error rate) data, the reception strength, etc., of the result processed by the baseband signal processing unit 9 are appropriately used.
- the gain of the variable gain amplifiers 5a, 5b, 7a, 7b is controlled.
- the LO signal input from the local signal input terminal 4 to the mixer 3 passes through the path 11 to the RF port of the mixer 3 due to leakage or the like, and the LO signal
- the DC offset occurs due to the mixing of the two.
- This DC offset is a so-called static offset that does not change with time.
- the LO signal input from the local signal input terminal 4 also passes through the path 12 to the input terminal 1 side of the LNA 2 to the RF port of the mixer 3, so that the LO signals Are mixed, thereby causing a DC offset.
- the DC offset varies in accordance with the gain set in the LNA2. Therefore, when the gain of LNA2 is set immediately after the start of receiving the RF signal, the DC offset amount fluctuates.
- the LO signal that has entered the input terminal 1 of the LNA 2 may flow back to the antenna and be radiated to the space, and then return to the antenna LNA 2 and the mixer 3 again.
- the DC offset in this case is V, a so-called dynamic DC offset, in which the DC offset amount dynamically varies according to the surrounding environment.
- a part of the RF signal amplified by the LNA 2 passes through the path 14 to the local signal input terminal 4 side of the mixer 3, and the RF signals are mixed.
- a DC offset has occurred.
- This DC offset has the property of a dynamic DC offset in which the DC offset amount fluctuates dynamically due to the effects of fading, etc., and the property of the DC offset amount stepwise fluctuating due to the LNA2 gain change. And both have.
- the DC offset amount also varies due to the secondary distortion of the mixer 3.
- reference numeral 3 indicates 3a and 3b in FIG. 1
- reference numeral 4 indicates 4a and 4b in FIG. 1
- reference numeral 5 indicates 5a and 5b in FIG.
- the output side of the mixer 3 is provided with a capacitor 15 for blocking the DC component of the signal output from the mixer 3.
- a high-noise filter (hereinafter, referred to as HPF) 16 that cuts off the DC component of the output signal of the mixer 3 is provided on the output side of the mixer 3 as in FIG. Is provided.
- Both the capacitor 15 and the HPF 16 have high-pass characteristics that allow only frequency components equal to or higher than the cutoff frequency to pass.
- the cutoff frequency of HPF16 has been selected to be sufficiently low so that the desired components of the signal are not lost, and is designed to be about 0.1% of the transmission rate in a communication system to which the signal processing device is applied (for example, , "B. Razavi," A 2.4-GHz CMOS Receiver for TEEE 802.11 Wireless LAN's "IEEE JSSC, Vol.34, No.10, pp.1382-1385 Oct. 1999").
- the signal processing apparatus shown in FIGS. 6 and 7 has a possibility that some of the desired components of the signal may be lost, and when the DC offset amount fluctuates with time, the DC offset may be reduced. There are common drawbacks such as difficulty in achieving both removal and storage of desired signal components.
- a feedback element 17 for performing DC servo feedback is added to the variable gain amplifier 5.
- the variable gain amplifier 5 and the feedback element 17 have a function of both the HPF and the amplifier.
- the signal processing device shown in FIG. 8 also has the same disadvantages as the signal processing devices shown in FIG. 6 and FIG.
- the DC offset included in the signal output from the mixer 3 is captured by the ADC 18, the DC offset amount is detected by the signal processing unit 19, and the digital Z analog converter , DAC) 20 is used to cancel the DC offset.
- the digital Z analog converter , DAC digital Z analog converter
- Patent Document 1 As another conventional technique for canceling the DC offset, there is a technique disclosed in Japanese Patent Application Laid-Open No. 8-316998 (hereinafter referred to as Patent Document 1).
- This technology basically uses HP F.
- the received signal level changes, the following DC offset fluctuations (1) and (2) occur.
- Patent Document 2 As another conventional technique for canceling the DC offset, there is a technique disclosed in Japanese Patent Application Laid-Open No. H11-186874 (hereinafter referred to as Patent Document 2).
- an amplifier having a differential input is provided, and one terminal of the amplifier is a signal input terminal, and the other terminal receives a negative feedback signal from a differential output.
- a non-linear element having low gain for small amplitude signals and high gain for large amplitude signals is inserted.
- the response time until the DC level of the signal output from the signal processing device converges can be shortened.
- Patent Document 2 has a clear disadvantage in response when a signal input to the signal processing device includes a steady DC offset.
- a DC offset voltage included in an input signal is much higher than an ideal midpoint potential and a desired signal component having a smaller amplitude than the DC offset voltage is superimposed on the signal.
- the DC voltage of the negative feedback signal is also significantly higher than the ideal midpoint potential close to the offset voltage. That is, the DC level of the signal output from the non-linear element inserted in the negative feedback path also becomes a voltage level considerably deviating from the ideal midpoint potential.
- the non-linear element is in a high gain state, and the HPF cutoff frequency remains high.
- the time constant of the HPF is determined by the absolute value of the DC offset included in the signal input to the signal processing device. It is not possible to converge the DC level of the output signal and increase the time constant of the HPF.
- Patent Document 3 As another conventional technique for canceling a DC offset, there is a technique disclosed in Japanese Patent Application Laid-Open No. 2003-224488 (hereinafter referred to as Patent Document 3).
- This technology uses HPF.
- the feature of this technology is that when any of the following (1) to (4) applies, it is determined that the period during which the DC offset is likely to increase is high, and the time constant of the HPF is set shorter than during normal operation. By doing so, it responds to DC offset fluctuations.
- An object of the present invention is to provide a signal processing device capable of coping with the response to dynamic DC offset and signal transmission that does not cause loss of a desired signal component.
- the signal processing device of the present invention outputs an input terminal to which an input signal is input, a first element that blocks a DC component of the input signal, and a signal output by the first element as an output signal.
- An output terminal a judging element for judging whether or not the voltage of the output signal has deviated from a preset detection threshold range, and when the judging element judges that the voltage of the output signal has deviated from the detection threshold range,
- a switch for connecting an output node of the first element to a power supply circuit.
- the output node of the first element is connected to the power supply circuit. Charge or discharge the current at the output node of the first element It can cancel the dynamically varying DC offset.
- the signal processing device of the present invention can achieve compatibility with a dynamically changing dynamic DC offset and transmission without loss of a desired signal component.
- FIG. 1 is a diagram showing a configuration example of a conventional direct conversion receiver.
- FIG. 2 is a diagram illustrating an example of a mechanism in which a DC offset occurs in a conventional signal processing device.
- FIG. 3 is a diagram for explaining another example of a mechanism in which a DC offset occurs in a conventional signal processing device.
- FIG. 4 is a diagram for explaining another example of a mechanism in which a DC offset occurs in a conventional signal processing device.
- FIG. 5 is a diagram for explaining another example of a mechanism in which a DC offset occurs in a conventional signal processing device.
- FIG. 6 is a diagram illustrating a configuration example of a conventional signal processing device.
- FIG. 7 is a diagram showing another configuration example of a conventional signal processing device.
- FIG. 8 is a diagram showing another configuration example of a conventional signal processing device.
- FIG. 9 is a diagram showing another configuration example of a conventional signal processing device.
- FIG. 10 is a diagram showing a configuration of a signal processing device according to a first embodiment of the present invention.
- FIG. 11 is a specific example of a direct conversion receiver using the signal processing device according to the present invention.
- FIG. 2 is a diagram showing a configuration of FIG.
- FIG. 12 is a diagram showing a configuration of a specific example 1 of the DC offset cancel loop 24 shown in FIG.
- FIG. 13 is a diagram showing an input voltage-output voltage characteristic of a first determination element 29 in the DC offset cancel loop 24 shown in FIG. 14 is a diagram showing an input voltage-output voltage characteristic of a second determination element 30 in the DC offset cancel loop 24 shown in FIG.
- FIG. 11 is a diagram illustrating the operation of the signal processing device shown in FIG.
- FIG. 11 is a diagram illustrating the operation of the signal processing device shown in FIG.
- FIG. 11 is a diagram illustrating the operation of the signal processing device shown in FIG.
- FIG. 18 is a diagram showing a configuration of a specific example 2 of the DC offset cancel loop 24 shown in FIG. 10.
- FIG. 19 is a diagram showing an input voltage-output voltage characteristic of a first determination element 33 in the DC offset cancel loop 24 shown in FIG.
- FIG. 20 is a diagram showing an input voltage-output voltage characteristic of a second determination element 34 in the DC offset cancel loop 24 shown in FIG.
- 21 is a diagram showing a configuration of a specific example 3 of the DC offset cancel loop 24 shown in FIG.
- FIG. 22 is a diagram showing an input voltage-output voltage characteristic of a connection point 47 in the DC offset cancel loop 24 shown in FIG. 21.
- FIG. 23 is a diagram showing an input voltage-output voltage characteristic of a connection point 46 in the DC offset cancel loop 24 shown in FIG. 21.
- FIG. 24 is a diagram illustrating a configuration of a signal processing device according to a second embodiment of the present invention.
- FIG. 25 is a diagram illustrating a configuration of a signal processing device according to a third embodiment of the present invention.
- FIG. 26 is a diagram showing a configuration of a signal processing device according to a fourth embodiment of the present invention.
- FIG. 27 is a diagram showing a configuration of a specific example 1 of the DC offset cancel loop 52 shown in FIG. 26.
- FIG. 28 is a diagram showing an input voltage-output voltage characteristic of a first determination element 29 in the DC offset cancel loop 52 shown in FIG. 27.
- FIG. 29 is a diagram showing an input voltage-output voltage characteristic of a second determination element 30 in the DC offset cancel loop 52 shown in FIG. 27.
- FIG. 30 is a diagram showing a configuration of a specific example 2 of the DC offset cancel loop 52 shown in FIG. 26.
- FIG. 31 is a diagram showing an input voltage-output voltage characteristic of a first determination element 33 in the DC offset cancel loop 52 shown in FIG. 30.
- FIG. 32 is a diagram showing an input voltage-output voltage characteristic of a second determination element 34 in the DC offset cancel loop 52 shown in FIG. 30.
- FIG. 33 is a diagram showing a configuration of a specific example 3 of the DC offset cancel loop 52 shown in FIG. 26.
- FIG. 34 is a diagram showing an input voltage-output voltage characteristic of a connection point 47 in the DC offset cancel loop 52 shown in FIG. 33.
- FIG. 35 is a diagram showing an input voltage-output voltage characteristic of a connection point 46 in the DC offset cancel loop 52 shown in FIG. 33.
- FIG. 36 is a diagram showing a configuration of a signal processing device according to a fifth embodiment of the present invention.
- FIG. 37 is a diagram showing a configuration of a signal processing device according to a sixth embodiment of the present invention.
- FIG. 38 is a diagram showing a configuration of a signal processing device according to a seventh embodiment of the present invention.
- FIG. 39 is a diagram showing a configuration of a signal processing device according to an eighth embodiment of the present invention.
- FIG. 40 is a diagram showing a configuration of a signal processing device according to a ninth embodiment of the present invention.
- FIG. 41 is a specific example of a direct conversion receiver using the signal processing device according to the present invention.
- FIG. 3 is a diagram showing a configuration of No. 2;
- FIG. 42 is a diagram showing a configuration of a specific example 3 of a direct conversion receiver using the signal processing device according to the present invention.
- FIG. 43 is a diagram showing a configuration of a specific example 4 of a direct conversion receiver using the signal processing device according to the present invention.
- FIG. 10 shows the configuration of the signal processing device according to the first embodiment of the present invention.
- the signal processing device according to the present embodiment includes an input terminal 21, an output terminal 22, an HPF 23 as a first element, and a DC offset canceller rape 24.
- the DC offset cancel loop 24 includes an LPF 25, a determination element 26, a first switch 27, and a second switch 28. [0034] When the determination element 26 determines that the voltage of the output signal output from the output terminal 22 is out of the preset detection threshold range, the determination element 26 selects one of the first switch 27 and the second switch 28. To connect the output node of HPF23 to the power supply circuit.
- two power supply circuits a first power supply circuit which is a power supply voltage of the signal processing circuit and a second power supply circuit which is a ground of the signal processing circuit, are provided as the power supply circuit.
- the determination element 26 determines that the voltage of the output signal is out of the detection threshold range, it drives the first switch 27 to connect the output node of the HPF 23 to the power supply voltage, or Drive switch 28 to connect the output node of HPF23 to ground.
- the power supply voltage of the signal processing circuit serving as the first power supply circuit may be shared with a power supply voltage for driving the entire signal processing circuit. Further, the first power supply circuit may be constituted by a constant voltage source that does not use the power supply voltage of the signal processing circuit.
- the signal processing device is applied to, for example, a direct comparison receiver as shown in FIG.
- the HPF 23 corresponds to the HPFs 23a, 23b, 23c, and 23d
- the DC offset cancel loop 24 corresponds to the DC offset cancel loops 24a, 24b, 24c, and 24d. Details of Fig. 11
- FIG. 12 shows a configuration of the specific example 1 of the DC offset cancel loop 24 shown in FIG.
- the determination element 26 has a configuration in which a first determination element 29 in which an inverting amplifier is connected to a CMOS inverter and a second determination element 30 having the same configuration as the first determination element 29 are connected in parallel.
- the first switch 27 and the second switch 28 include a p-type MOSFET 31 and an n-type MOSFET 32, respectively.
- the output node of the second decision element 30 is connected to the gate terminal of the p-type MOSFET 31, and the output node of the first decision element 29 is connected to the gate terminal of the n-type MOSFET 32.
- the CMOs of the first determination element 29 and the second determination element 30 The configuration in which the inverting amplifier connected after the S inverter is omitted, the p-type MOSFET 31 of the first switch 27 is replaced by an n-type MOSFET, and the n-type MOSFET 32 of the second switch 28 is replaced by a p-type MOSFET #2.
- FIG. 13 and FIG. 14 show input voltage-output voltage characteristics of the first determination element 29 and the second determination element 30, respectively.
- VO is the DC potential of the signal input to the determination element 26, and is determined by the DC potential of the signal output from the LPF 25. That is, VO is determined by the DC potential of the signal output from the HPF 23, the input bias of the element connected to the output terminal 22, and the like.
- VI and V2 are the upper and lower thresholds of the detection threshold range for detecting the variation of the DC offset, respectively, which are set in the first determination element 29 and the second determination element 30 .
- the thresholds VI and V2 are used to change the current drive capability ratio between the n-type MOSFET and the p-type MOSFET constituting the first-stage CMOS inverter in each of the first determination element 29 and the second determination element 30. Adjusted by.
- the thresholds VI and V2 are designed to be V2, V0, and VI.
- the first decision element 29 outputs a low level
- the second decision element 30 outputs a high level, whereby the switch 27 is output. , 28 are both turned off. Therefore, when the voltage of the signal input to the determination element 26 is in the range from VI to V2, the signal output from the HPF 23 is output as it is from the output terminal 22 as an output signal.
- the DC offset cancel loop 24 has the configuration of the specific example 1 shown in FIG.
- the threshold values VI and V2 set for each of the first determination element 29 and the second determination element 30 are set so that the amplitude of the signal output from the LPF 25 falls within the range from the threshold VI to V2 in the steady state. Value.
- the signal that has passed through the HPF 23 among the input signals from the input terminal 21 shown in FIG. 10 is output from the output terminal 22 as an output signal.
- the DC potential of the signal output from the output terminal 22 is determined by the DC potential of the signal output from the HPF 23, the input bias to an element connected to the output terminal 22, and the like.
- HPF2 The DC offset cancellation loop 24 to output node 3 does not work because both the first switch 27 and the second switch 28 are off. Note that the cutoff frequency of the HPF 23 is selected to be sufficiently low so that a desired signal component is not lost.
- FIGS. 15 to 17 illustrate an operation of converging the DC level of the output signal of the output terminal 22 when the input signal from the input terminal 21 shown in FIG. 10 includes a positive DC offset. The figure is shown.
- the cutoff frequency of the HPF 23 is selected to be sufficiently low. Therefore, even when the DC offset amount included in the input signal fluctuates in a step-like manner, the HPF 23 outputs the step-like input signal to the output terminal 22 as it is (see the output waveform of the HPF 23 in the left part of FIG. 15). ).
- the signal output from the HPF 23 is extracted by the low-frequency component LPF 25 and input to the determination element 26 (see the output waveform of the LPF 25 on the right side of FIG. 15).
- the determination element 26 determines that the time variation of the DC offset is at a level that cannot be ignored.
- the DC offset included in VO changes to a positive DC offset exceeding threshold VI.
- both the first determination element 29 and the second determination element 30 constituting the determination element 26 output a high level, and turn on the second switch 28.
- the output node of the HPF23 is connected to the ground, so that the current at the output node of the HPF23 is immediately discharged to the ground (see the current indicated by the broken line in FIG. 16). This will cancel the positive DC offset.
- the decision element 26 turns off the second switch 28, thereby ending the discharge (the output of the left and right HPF23 and LPF25 in FIG. 17). (See waveform).
- the waveform shown by the broken line is the waveform when it is assumed that the second switch 28 does not operate, and the solid line is the waveform when the second switch 28 operates. It is a waveform when performing.
- both the first determination element 29 and the second determination element 30 constituting the determination element 26 Outputs a low level and turns on the first switch 27. Then, HPF2 Since the output node of 3 is connected to the supply voltage, switch 27 charges the current that flows instantaneously from the output node of HPF23, thereby canceling the negative DC offset.
- the above charging / discharging operation is performed within a time sufficiently shorter than the time constant of HPF23. Can be done.
- the amplitude of the signal output from the LPF 25 is within the range in which the DC offset cancel operation by the DC offset cancel loop 24 stops, that is, from the threshold VI to V2, unless the DC offset changes again. Keep within the range. That is, the steady state continues.
- the LPF 25 plays a role in adjusting the response time of the DC offset cancel loop 24 and preventing malfunction due to an instantaneous increase in amplitude.
- the cutoff frequency of the LPF 25 When the cutoff frequency of the LPF 25 is high, a high frequency component fluctuated by the DC offset is also transmitted to the input node of the decision element 26. Therefore, when the DC level of the signal output from the HPF 23 falls within the range from the threshold value VI to V2, and at the same time the first switch 27 or the second switch 28 is turned off, the DC offset is reduced. The cancel operation ends.
- the cutoff frequency of the LPF 25 is determined by the fact that the DC level of the signal output from the HPF 23 falls within the range of the threshold VI to V2, and at the same time, the shift of the first switch 27 or the second switch 28 It is set to turn off. Therefore, the DC offset of VI-VO remains for a positive DC offset, and the DC offset of V2-VO remains for a negative DC offset.
- the DC level of the signal output from the HPF 23 can be optimized.
- the signal processing device is an OFDM system (Orthogonal
- the present invention is applied to a direct conversion receiver used in a frequency division multiplexing system (orthogonal frequency division multiplexing transmission system).
- the signal amplitude may increase instantaneously because the phases of the subcarriers are aligned at a certain moment. If this signal amplitude is out of the range from the threshold VI of the decision element 26 to V2, the circuit in the direct conversion receiver will malfunction. In order to prevent this, in the present embodiment, the frequency component of the signal input to the determination element 26 is limited by the LPF 25.
- FIG. 11 shows an example in which the signal processing device according to the present embodiment is applied to a direct conversion receiver.
- FIG. 11 shows only one of the two paths on which the signal amplified by the LNA 2 is branched.
- the conventional technique using a simple high-pass element as shown in FIGS. 6 to 8 can achieve both transmission and the response to the dynamic offset without loss of the desired signal component.
- the DC offset is captured by the ADC 18, the signal processing unit 19 detects the amount of the DC offset, and the DAC 20 generates a signal for canceling the DC offset, which is more complicated than the conventional technology. It has the advantage that it does not require an ADC or DAC, does not need to supply a control signal synchronized with the time slot to an external power, and can cope with fluctuations in the DC offset within the desired reception time slot.
- the DC offset cancel operation is performed by directly monitoring the change in the DC offset.
- the advantage that the DC offset cancel operation can be performed more reliably than the conventional technology disclosed in Patent Document 1 that indirectly observes the variation of the DC offset based on the received signal level. There is. That is, even if the received signal level does not fluctuate, if the DC offset fluctuates, the operation of converging the DC level of the output signal of the output terminal 22 is reliably performed. On the other hand, if the DC offset does not fluctuate even if the received signal level fluctuates, no extra operation for dropping the desired signal component is performed. Also detects that the received signal level has changed and outputs it to the HPF Since a control device that generates a control signal to be generated is not required, the hardware configuration is simple.
- the input terminal 21 and the output terminal 22 are separated from each other by the HPF 23 in terms of force DC.
- the problem of the conventional technology disclosed in Patent Document 2 in which the DC level of the output signal of the output terminal 22 cannot be converged and the time constant of the HPF 23 cannot be increased. That is, in the present embodiment, when the charging of the current from the output node of the HPF 23 by the first switch 27 ends, no signal is transmitted to the determination element 26, and thus the state returns to the steady state reliably.
- FIG. 18 shows the configuration of the specific example 2 of the DC offset cancel loop 24 shown in FIG.
- the determination element 26 includes a first determination element 33 that detects a positive DC offset included in the DC potential VO of the signal input to the determination element 26, and a second determination element that detects a negative offset included in the DC potential VO. This is the same as the judgment element 34.
- the first determination element 33 includes an n-type MOSFET 35 and resistors 37 and 38 connected in series between the power supply voltage of the signal processing device and the ground. The source terminal of the n-type MOSFET 35 is connected to a connection point between the resistors 37 and 38, and the connection point is an output node of the first determination element 33.
- the second judging element 34 also includes a p-type MOSFET 36 and resistors 39 and 40 connected in series between the power supply voltage of the signal processing device and the ground.
- the source terminal of the p-type MOSFET 36 is connected to a connection point of the resistors 39 and 40, and the connection point is an output node of the second determination element 34.
- the input nodes of the first determination element 33 and the second determination element 34 are connected in parallel.
- the output node of the first decision element 33 is connected to the input node of the second switch 28, and the output node of the second decision element 34 is connected to the input node of the first switch 27. Note that the configuration of the first switch 27 and the second switch 28 is the same as that of the specific example 1 shown in FIG.
- FIG. 19 and FIG. 20 show input voltage-output voltage characteristics of the first determination element 33 and the second determination element 34, respectively.
- VI and V2 are the upper and lower threshold values of the detection threshold range for detecting the variation of the DC offset, respectively, and are set in the first determination element 33 and the second determination element.
- the threshold VI is adjusted by changing the values of the resistors 37 and 38 connected to the source terminal of the n-type MOSFET 35.
- the threshold VI is the value of the first judgment element 33 When the DC potential of the signal input to the input terminal exceeds VI, the potential of the signal output from the first determination element 33 exceeds the threshold value VSWn-th of the n-type MOSFET 32 forming the second switch 28. Designed.
- the threshold value V2 is adjusted by changing the values of the resistors 39 and 40 connected to the source terminal of the p-type MOSFET 36.
- the threshold value V2 falls below the DC potential force SV2 of the signal input to the second determination element 34
- the potential of the signal output from the second determination element 34 configures the first switch 27. It is designed to be lower than the threshold VSWp-th of MOSFET31.
- VDCn is a DC potential of the first determination element 33 in a steady state without a DC offset, and is appropriately selected such that the second switch 28 is turned off.
- VDCp is a DC potential of the second determination element 34 in a steady state without a DC offset, and is appropriately selected so that the first switch 27 is turned off.
- FIG. 21 shows the configuration of the third example of the DC offset cancel loop 24 shown in FIG.
- the gate terminals of the n-type MOSFET 41 and the p-type MOSFET 42 are connected in parallel as input terminals of the decision element 26 so as to perform a source follower operation.
- resistors 43, 44, and 45 are connected in series between the power supply voltage of the signal processing device and the ground.
- the source terminal of the p-type MOSFET 42 is connected to the first connection point 46 of the connection points of the resistors 43, 44, and 45
- the source terminal of the n-type MOSFET 41 is connected to the first connection point of the connection points of the resistors 43, 44, and 45.
- the first connection point 46 and the second connection point 47 are output nodes of the decision element 26, respectively.
- the first connection point 46 is connected to the input node of the first switch 27, and the second connection point 47 is connected to the input node of the second switch 28. Note that the configuration of the first switch 27 and the second switch 28 is the same as that of the specific example 1 shown in FIG.
- FIG. 22 and FIG. 23 show the input voltage-output voltage characteristics of the connection points 47 and 46, respectively.
- VI and V2 are the upper and lower limits of the detection threshold range for detecting the variation of the DC offset, respectively, and are set in the determination element 26.
- the thresholds VI and V2 are adjusted by changing the values of the resistors 43, 44 and 45.
- the threshold VI is designed so that the voltage at the node 47 becomes VSWn-th when the DC potential of the signal input to the n-type MOSFET 41 becomes VI.
- the threshold V2 is the DC voltage of the signal input to the p-type MOSFET 42. It is designed so that the voltage at the node 46 becomes VSWp-th when the potential becomes V2.
- VSWn — th is a threshold value of the n-type MOSFET 32 constituting the second switch 28.
- VSWp-th is a threshold value of the p-type MOSFET 31 constituting the first switch 27.
- VDCn is the DC potential of the connection point 47 in a steady state with no DC offset, and is appropriately selected so that the second switch 28 is turned off.
- VDCp is the DC potential of the connection point 46 in a steady state with no DC offset, and is appropriately selected so that the first switch 27 is turned off.
- FIG. 24 shows the configuration of the signal processing device according to the second embodiment of the present invention.
- the signal processing device according to this embodiment is different from the first embodiment shown in FIG. 10 in that the first switch 27 allows a current to flow to the first switch 27, which is different from the power supply voltage of the signal processing device.
- the point that the second switch 28 is connected to the constant current source 48 is different from the point that the second switch 28 is connected to the constant current source 49 into which the current flows from the second switch 28 that is not connected to the ground of the signal processing device.
- the charge / discharge current flows between the output node of the HPF 23 and the constant current sources 27 and 28. The effect can be obtained.
- FIG. 25 shows the configuration of a signal processing device according to the third embodiment of the present invention.
- the signal processing device according to the present embodiment is different from the first embodiment shown in FIG. 10 in that the LPF 25 is omitted.
- the LPF 25 since the LPF 25 is omitted, all signals output from the HPF 23 are transmitted to the determination element 26. Even if the LPF 25 is omitted, the high-frequency component contained in the signal output from the HPF 23 is suppressed to some extent in the circuit before the input terminal 21! The response time has an optimal value, and the effects intended by the present invention can be obtained. Similarly, even if the LPF 25 is omitted, the response time of the DC offset cancel loop 24 becomes an optimum value depending on the high frequency characteristics of the HPF 23 and the assumed time constant of the DC offset. Obtainable.
- the signal processing device according to the present embodiment can be applied to a communication system in which the LPF 25 is omitted and an instantaneous increase in amplitude does not occur.
- FIG. 26 shows the configuration of the signal processing device according to the fourth embodiment of the present invention.
- the signal processing apparatus according to this embodiment is different from the first embodiment shown in FIG. 10 in that the DC offset cancel loop 24 is changed to a DC offset cancel loop 52 having a threshold adjustment function. More specifically, the DC offset cancel loop 52 outputs a signal for adjusting the upper and lower threshold values of the detection threshold range set in the determination element 26, as compared with the DC offset cancel loop 24. The difference is that a control terminal 50 is provided.
- the configuration including the determination element 26 and the control terminal 50 is referred to as a determination element 51.
- the amplitude of the desired signal component included in the input signal changes due to, for example, gain switching in a circuit preceding the input terminal 21 and is input to the determination element 26 in a steady state. Even if the signal amplitude becomes too small or too large, the DC offset cancel loop 52 operates and cancels the desired signal component of the output signal without causing a malfunction. Can respond appropriately. It is clear that other basic functions are the same as those of the first embodiment shown in FIG.
- control terminal 50 may be used as a terminal for outputting a signal for stopping the operation of detecting the DC offset fluctuation. Further, two control terminals corresponding to the control terminal 50 may be provided, the threshold of the determination element 26 may be adjusted by one control terminal, and the DC offset fluctuation detection operation may be stopped by the other control terminal.
- FIG. 27 shows the configuration of the specific example 1 of the DC offset cancel loop 52 shown in FIG.
- the DC offset cancellation loop 52 according to this example is the DC offset cancellation loop 52 shown in FIG.
- the p-type MOSFET 53 is connected in parallel with the p-type MOSFET constituting the first-stage CMOS inverter, and the source terminal of the p-type MOSFET 53 is connected via the switch 54.
- the n-type MOSFET 55 is connected in parallel with the n-type MOSFET constituting the first-stage CMOS inverter, and the source terminal of the n-type MOSFET 55 is connected to the power supply voltage.
- the switch 56 are connected to the ground via the switch 56, and the onZoff of the switches 54 and 56 is controlled by a signal from the control terminal 50.
- the p-type MOSFET 53 and the first CMOS of the second decision element 30 that constitute the first stage CMOS inverter of the first decision element 29 It is possible to change the current drive capability ratio of the n-type MOSFET 55 constituting the inverter. Thereby, the logical threshold value of the CMOS inverter can be changed.
- the threshold value set for the first determination element 29 can be adjusted to VI, VI ', etc. .
- the threshold value set for the second determination element 30 can be adjusted to V2, V2 ', and the like. .
- the n-type MOSFET 53 and the p-type MOSFET 56 are connected to the power supply voltage and the ground via the switches 54 and 56, respectively.
- the on-Zoff of the switches 54 and 56 is controlled by a signal from the control terminal 50. This makes it possible to stop the operation of detecting DC offset fluctuation.
- FIG. 30 shows the configuration of the specific example 2 of the DC offset cancel loop 52 shown in FIG.
- the DC offset cancel loop 52 according to this example is different from the DC offset cancel loop 24 shown in FIG. 18 in that the resistor 38 is replaced by the variable resistor 57 in the first determination element 33 and the second In the judgment element 34, the difference is that the resistor 39 is replaced with a variable resistor 58, and that the resistance values of the variable resistors 57, 58 are controlled by a signal from a control terminal 50 (not shown in FIG. 30).
- the resistance values of the variable resistors 57 and 58 are controlled by a signal from the control terminal 50. ing.
- the threshold value set for the first decision element 33 is adjusted to VI, VI ', etc. with respect to VSWn-th. It is possible to do.
- the threshold value set for the second determination element 34 is set to V2, V2 ', etc. with respect to VSWp-th. It can be adjusted.
- the force in which the resistors 38, 39 shown in Fig. 18 are replaced with the variable resistors 57, 58 is not limited to this configuration.
- a line circuit composed of a switch and a resistor connected in series as shown in Fig. 27 is connected in parallel to the resistor 38 to connect to the ground, and a switch and a resistor as shown in Fig. 27 are connected.
- the resistor 37 is connected to the power supply voltage via the switch as shown in FIG. 27, and the resistor 40 is connected to the ground via the switch as shown in FIG.
- the onZoff of the switch may be controlled by a signal from the control terminal 50. Even with this configuration, it is possible to stop the operation of detecting DC offset fluctuation.
- FIG. 33 shows the configuration of specific example 3 of the DC offset cancel loop 52 shown in FIG.
- the DC offset cancel loop 52 according to this example is different from the DC offset cancel loop 24 shown in FIG. 21 in that the resistors 43 and 45 are replaced with variable resistors 59 and 60, respectively. The difference is that the resistance value is controlled by a signal from the control terminal 50 (not shown in FIG. 33).
- the threshold value is adjusted to VI, VI ′, or the like, or the connection point 46 in FIG.
- the threshold can be adjusted to V2, V2 ', etc.
- the resistors 43 and 45 shown in FIG. 21 are replaced with the variable resistors 59 and 60, but the present invention is not limited to this configuration.
- a line circuit composed of a switch and a resistor connected in series as shown in FIG. Connect in parallel with 3 to the power supply voltage, and connect a line circuit consisting of a switch and a resistor in series as shown in Fig. 27 in parallel with the resistor 45 to the ground.
- a configuration may be employed, and the onZoff of the switch may be controlled by a signal from the control terminal 50. Also in this configuration, it is possible to adjust the threshold value set in the determination element 51.
- the resistors 43 and 45 shown in FIG. 21 are replaced with switches as shown in FIG. 27 instead of the variable resistors 59 and 60, and the connection points 46 and 47 are connected to the power supply voltage and The onZoff of the switch may be controlled by a signal from the control terminal 50 by connecting to the ground. Even with this configuration, it is possible to stop the operation of detecting the DC offset fluctuation.
- FIG. 36 shows the configuration of the signal processing device according to the fifth embodiment of the present invention.
- the signal processing apparatus according to this embodiment is different from the first embodiment shown in FIG. 10 in that the DC offset cancel loop 24 is changed to a DC offset cancel loop 52 having a threshold adjustment function. More specifically, the DC offset cancel loop 52 is different from the DC offset cancel loop 24 in that a judging element 26 is connected in parallel with the judging element 26, and a judging element 61 having a detection threshold range different from that of the judging element 26 is added.
- the point that switches 62 and 63 as switching means are added, and the output nodes of the decision elements 26 and 61 and the first switch 27, in that switches 64 to 67 as switching means are added between the input node of the second switch 28 and the input node of the second switch 28.
- the number of judging elements connected in parallel may be two or more.
- the configuration including the determination elements 26 and 61 and the switches 62 to 67 is referred to as a determination element 51.
- the amplitude of the desired signal component included in the input signal changes due to, for example, gain switching in a circuit preceding the input terminal 21 and is input to the determination element 26 in a steady state. Even if the signal amplitude becomes too small or too large, select another judgment element (such as 61) with an appropriate threshold and switch to the selected other judgment element using switches 62 to 67. Thus, it is possible to appropriately cope with a change in DC offset without causing a malfunction such as the DC offset cancel loop 52 operating to cancel a desired signal component of the output signal.
- Other basic functions are the first one shown in FIG. It is clear that this embodiment is similar to the embodiment.
- FIG. 37 shows the configuration of the signal processing device according to the sixth embodiment of the present invention.
- the signal processing apparatus according to this embodiment is different from the first embodiment shown in FIG. 10 in that the DC offset cancel loop 24 is changed to a DC offset cancel loop 52 having a threshold adjustment function. More specifically, the DC offset cancel loop 52 is different from the DC offset cancel loop 24 in that a third element, a variable gain amplifier 68, is added between the LPF 25 and the input node of the decision element 26. The points are different.
- the configuration including the determination element 26 and the variable gain amplifier 68 is referred to as a determination element 51.
- the gain of the variable gain amplifier 68 can be improved.
- the DC offset cancel loop 52 operates and cancels the desired signal component of the output signal without causing an erroneous operation. it can.
- FIG. 38 shows the configuration of the signal processing device according to the seventh embodiment of the present invention.
- the signal processing device according to this embodiment is different from the first embodiment shown in FIG. 10 in that the DC offset cancel loop 24 is changed to a DC offset cancel loop 69 having a threshold adjustment function.
- the DC offset cancel loop 69 is different from the DC offset cancel loop 24 in that a variable gain amplifier 70 as a second element is added between the output node of the HPF 23 and the output terminal 22,
- the determination element 51 having the threshold adjustment function described in the fourth to sixth embodiments (FIGS. 26, 36, and 37) is provided instead of the determination element 26.
- a gain variable amplifier for amplifying a signal of an IF (Intermediate Frequency) stage as a whole is provided. It can also have the function of
- the DC offset cancel loop 69 is operated by the signal output from the variable gain amplifier 70, the signal output from the variable gain amplifier 70 when the gain of the variable gain amplifier 70 is changed Even if the DC level fluctuates, the DC offset cancel operation is performed.
- the thresholds VI and V2 for detecting the fluctuation of the DC offset are set so that the amplitude of the signal output from the variable gain amplifier 70 is between VI and V2 according to each gain set in the variable gain amplifier 70. Set to fit.
- the cutoff frequency of the LPF 25 is adjusted according to the high-frequency characteristics of the variable gain amplifier 70, and is designed so that the response time of the DC offset cancel loop 69 is appropriate as a whole. Also, depending on the high frequency characteristics of the variable gain amplifier 70, the LPF 25 can be omitted.
- variable gain amplifier 70 may be an attenuator! One may replace the variable gain amplifier 70 with an LPF for channel selection!
- variable gain amplifier 68 of the sixth embodiment a configuration may be adopted in which the variable gain amplifier 68 of the sixth embodiment is added.
- control is performed so that the product of the gain of the variable gain amplifier 70 and the gain of the variable gain amplifier 68 is constant.
- the thresholds VI and V2 for detecting the fluctuation of the DC offset are obtained from the amplitude power of the signal output from the variable gain amplifier 70 according to the product of the gain of the variable gain amplifier 70 and the gain of the variable gain amplifier 68. What is necessary is just to set it within V2.
- FIG. 39 shows the configuration of the signal processing device according to the eighth embodiment of the present invention.
- the signal processing device according to the present embodiment is different from the seventh embodiment shown in FIG. 38 in that the HPF23 has a capacitance of 71, and the bias circuit of the variable gain amplifier 70 connected to the output node of the HPF23 has a resistor of 72, The difference is that it is configured using 73.
- the present embodiment in addition to the basic functions similar to those of the first embodiment shown in FIG. 10, it can also have a function as a variable gain amplifier for amplifying the signal of the IF stage as a whole. .
- a DC offset cancel loop is generated by a signal output from variable gain amplifier 70. Since the 69 is operated, even if the DC level of the signal output from the variable gain amplifier 70 changes when the gain of the variable gain amplifier 70 is changed, the DC offset canceling operation is performed. At this time, the thresholds VI and V2 for detecting the fluctuation of the DC offset are set so that the amplitude of the signal output from the variable gain amplifier 70 is between VI and V2 according to each gain set in the variable gain amplifier 70. Set to fit.
- the cut-off frequency of the LPF 25 is adjusted according to the high-frequency characteristics of the variable gain amplifier 70, and is designed so that the response time of the DC offset cancel loop 69 becomes appropriate as a whole. Also, depending on the high frequency characteristics of the variable gain amplifier 70, the LPF 25 can be omitted.
- variable gain amplifier 70 may be an attenuator! One may replace the variable gain amplifier 70 with an LPF for channel selection!
- FIG. 40 shows the configuration of the signal processing device according to the ninth embodiment of the present invention.
- the signal processing device according to this embodiment is different from the first embodiment shown in FIG. 10 in that the DC offset cancel loop 24 is changed to a DC offset cancel loop 74.
- the DC offset cancel loop 74 is a signal cutoff switch between the connection point of the first switch 27 and the second switch 28 and the output node of the HPF 23 as compared with the DC offset cancel loop 24. The difference is that a certain switch 75 is added. This switch 75 separates the mechanism for canceling the DC offset (the mechanism consisting of the LPF 25, the decision element 26, the first switch 27 and the second switch 28) from the output node of the HPF 23, and stops the operation of canceling the DC offset. It is provided to let you.
- a switch 75 that is a signal cutoff switch is added between the connection point of the first switch 27 and the second switch 28 and the output node of the HPF 23. It is not limited to this configuration. For example, instead of or in addition to switch 75, another signal blocking between the output node of LPF 25 and the input node of decision element 26 A switch may be provided.
- FIG. 11 shows a configuration of a specific example 1 of a direct conversion receiver using the signal processing device according to the present invention. Note that FIG. 11 shows only one of the two paths from which the signal amplified by the LNA2 is branched (the same applies to FIGS. 41 to 43 below).
- the direct conversion receiver according to the present specific example is different from the conventional example shown in Fig. 1 in the input / output stage of variable gain amplifiers 5, 7 (corresponding to variable gain amplifiers 5a, 7a in Fig. 1).
- the HPF 23a, 23b, 23c, 23d and the DC offset canceller correspond to the HPF 23 and the DC offset cancel loop 24 shown in the signal processing device (FIGS. 10, 24, and 25) according to the first to third embodiments.
- the difference is that loops 24a, 24b, 24c and 24d are added.
- FIG. 41 shows the configuration of Example 2 of the direct conversion receiver using the signal processing device according to the present invention.
- the direct conversion receiver according to this example is different from the example 1 shown in FIG. 11 in that the signal processing device according to the ninth embodiment (FIG. 40) is used instead of the DC offset cancel loops 24a, 24b, 24c, and 24d.
- the difference is that DC offset cancel loops 74a, 74b, 74c, and 74d corresponding to the DC offset cancel loop 74 shown by are set.
- the gain setting of the entire receiver is determined, for example, immediately after the start-up of the direct conversion receiver, and during the period, the DC offset cancel loop after the variable gain amplifier 7
- the operation of canceling the DC offset by 74d can be stopped. Therefore, despite the DC offset fluctuation, the desired signal
- the DC offset cancel loop 74 does not operate to cancel the desired signal component of the output signal due to the amplitude of the signal becoming too large or too small.
- the baseband signal processing unit 9 erroneously measures the signal strength of the received signal, and an erroneous signal is sent from the gain control unit (gain setting unit) 10 to the LNA 2 and the variable gain amplifiers 5 and 7, so that the receiver If the overall gain setting is incorrect, it is possible to avoid the problems. It is clear that the other basic functions are the same as those in the first embodiment shown in FIG.
- FIG. 42 shows the configuration of a specific example 3 of a direct conversion receiver using the signal processing device according to the present invention.
- the direct conversion receiver according to this embodiment is different from the direct conversion receiver according to the first embodiment shown in FIG. 11 in that instead of the DC offset cancel loops 24a, 24b, 24c, and 24d, the signal processing devices (the fourth to sixth embodiments) The difference is that DC offset cancellation loops 52a, 52b, 52c, and 52d corresponding to the DC offset cancellation loop 52 shown in FIGS. 26, 36, and 37) are provided.
- the control terminal 50 By controlling the thresholds of the DC offset cancellation loops 52a, 52b, 52c, 52d, the DC offset cancellation loops 52a, 52b, 52c, 52d do not operate and cancel the desired signal component of the output signal. As a result, it is possible to realize an appropriate response to the fluctuation of the DC offset. It is clear that the other basic functions are the same as those in the specific example 1 shown in FIG.
- FIG. 43 shows a configuration of a specific example 4 of a direct conversion receiver using the signal processing device according to the present invention.
- the direct conversion receiver according to this example is different from the conventional example shown in FIG. 1 in that the variable gain amplifiers 5a and 7a are replaced by signal processing devices according to the seventh and eighth embodiments (FIGS. 28 and 29).
- the difference is that the HPFs 23a and 23b and the DC offset cancel loops 69a and 69b corresponding to the HPF 23 and the DC offset cancel loop 69 (integrated with the variable gain amplifier 70) shown in () are added.
- variable gain amplifiers 70a and 70b It is possible to obtain the same function with a smaller number of elements than in the specific example 3 which is not only provided with the function of adjusting the threshold values of the DC offset cancellation loops 69a and 69b according to the gain of. It is clear that the other basic functions are the same as those in the specific example 1 shown in FIG.
- the embodiments of the present invention have been described above. However, it goes without saying that the present invention is not limited to the above-described embodiments, but can be modified within the technical idea of the present invention. For example, the present invention can be applied not only to the direct conversion receiver described above, but also to a communication device having a DC offset problem.
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Abstract
Description
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US11/569,117 US7565127B2 (en) | 2004-05-14 | 2005-04-14 | Signal processing unit |
JP2006513509A JP4235841B2 (ja) | 2004-05-14 | 2005-04-14 | 信号処理装置および信号処理方法 |
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Cited By (2)
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JP2009267462A (ja) * | 2008-04-22 | 2009-11-12 | Nec Electronics Corp | 信号処理装置 |
JP2009544207A (ja) * | 2006-07-20 | 2009-12-10 | テレフオンアクチーボラゲット エル エム エリクソン(パブル) | 無線受信機 |
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JP2008035031A (ja) * | 2006-07-27 | 2008-02-14 | Matsushita Electric Ind Co Ltd | 混合装置とこれを用いた高周波受信装置 |
US20090088106A1 (en) * | 2007-09-27 | 2009-04-02 | Nanoamp Solutions Inc. (Cayman) | Radio frequency filtering |
JP5257696B2 (ja) * | 2009-05-29 | 2013-08-07 | ソニー株式会社 | 復調器および通信装置 |
JP5440022B2 (ja) * | 2009-08-24 | 2014-03-12 | ソニー株式会社 | 復調器 |
US8891686B2 (en) * | 2011-10-26 | 2014-11-18 | Source Photonics, Inc. | Data signal detection in optical and/or optoelectronic receivers and/or transceivers |
US9671427B2 (en) | 2013-04-24 | 2017-06-06 | Keysight Technologies, Inc. | Dual output high voltage active probe with output clamping and associated methods |
US9423422B2 (en) * | 2013-04-24 | 2016-08-23 | Keysight Technologies, Inc. | Oscilloscope probe having output clamping circuit |
US10009193B2 (en) * | 2015-02-23 | 2018-06-26 | Photonic Systems, Inc. | Methods and apparatus for source and load power transfer control |
US10014036B1 (en) * | 2016-12-29 | 2018-07-03 | Intel Corporation | Low power and area efficient memory receiver |
US10530306B2 (en) * | 2018-04-13 | 2020-01-07 | Nxp Usa, Inc. | Hybrid power amplifier circuit or system with combination low-pass and high-pass interstage circuitry and method of operating same |
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JPH08316998A (ja) | 1995-05-15 | 1996-11-29 | Matsushita Electric Ind Co Ltd | 受信装置 |
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JP2000115740A (ja) | 1998-10-08 | 2000-04-21 | Alps Electric Co Ltd | テレビジョン信号送信機 |
JP2000315960A (ja) | 1999-04-30 | 2000-11-14 | Toshiba Corp | マイクロ波受信装置 |
JP2001136461A (ja) | 1999-11-04 | 2001-05-18 | Alps Electric Co Ltd | Agc回路 |
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JP2002118443A (ja) | 2000-10-06 | 2002-04-19 | Niigata Seimitsu Kk | フィルタ回路 |
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US7110734B2 (en) * | 2002-09-05 | 2006-09-19 | Maxim Integrated Products Inc. | DC offset cancellation in a zero if receiver |
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2005
- 2005-04-14 WO PCT/JP2005/007200 patent/WO2005112282A1/ja active Application Filing
- 2005-04-14 JP JP2006513509A patent/JP4235841B2/ja not_active Expired - Fee Related
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JP2003115779A (ja) * | 2001-08-13 | 2003-04-18 | Samsung Electronics Co Ltd | マルチチップモジュールを利用してdcオフセットを減少させたダイレクトコンバージョン送受信器 |
US20030109241A1 (en) * | 2001-12-12 | 2003-06-12 | Samsung Electronics Co., Ltd. | Direct-conversion receiver for removing DC offset |
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US20080090545A1 (en) | 2008-04-17 |
US7565127B2 (en) | 2009-07-21 |
JP4235841B2 (ja) | 2009-03-11 |
JPWO2005112282A1 (ja) | 2008-03-27 |
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