JPH1174757A - Frequency adjuster - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize cut-off frequency of a filter formed by combining a frequency dependent resistance circuit and a resistor. SOLUTION: A reference signal is inputted in a terminal 13 of a first circuit 20, a signal with a phase corresponding to the product of capacitance and resistance is outputted to a terminal 15. Phase difference between the terminals 13 and 15 is set as a specified value according to the value of phase error voltage detected by a phase comparator 33 and the product of the capacitance and the resistance. The phase error voltage is inputted in a currant amplifier 46 to constitute the frequency dependent resistance circuit of a second circuit 21. A filter circuit is constituted by connecting the resistor 52 at one end of the frequency dependent resistance circuit, inputting the signal in a terminal 11 and taking the signal from a terminal 12. In this case, the first circuit 20 and the second circuit 21 are constituted by using the capacitor and the resistance formed by the same manufacturing process of an integrated circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band-pass filter for extracting a color signal from a composite video signal by combining a frequency-dependent resistor circuit and a resistor, a low-pass filter for removing harmonics after demodulating the color signal, and an equalizer amplifier for audio. Alternatively, the present invention relates to a frequency adjusting device for stabilizing a cutoff frequency of a low-pass filter or the like for extracting I and Q outputs of a BS tuner signal.

[0002]

2. Description of the Related Art Conventionally, a passive filter or an active filter has been constructed by combining a resistor, a capacitor, a coil or an operational amplifier, and a phase of a signal taken out here changes greatly with a change in frequency. In contrast, Japanese Patent Application No. 8-044
No. 497 has filed an application for a frequency-dependent resistor circuit capable of selecting a frequency without changing the phase of an output signal in a pass band, and a filter device using the same.

FIG. 5 is a diagram of a filter device using a conventional frequency-dependent resistance circuit. In FIG. 5, reference numerals 1 to 5 denote voltage-current converters for converting a voltage applied to a positive input into a current based on a negative input reference voltage and outputting the current. Expressing the ratio of the output current to the input voltage in gm, the voltage-
The values of the current conversion rates gm of the current converters 1 to 4 are gm1, gm
2, gm3, gm4, gm of the voltage-current converter 5
11 is defined. Note that the current conversion rate gm is given as the reciprocal of the sum of the emitter resistances of the differential amplifier circuit constituting the voltage-current converter. 7 to 10 are capacitors;
Capacitance values of 10 to 10 are defined as C1, C2, C3, and C4, respectively. The impedance jX of the reactive load using a capacitor is jX = -j (1 / wC). Note that w is the angular frequency of the signal to be handled. Based on the above constants, the impedance Zin4 when the frequency-dependent resistance circuit is viewed from the terminal 11 is as follows: Zin4 = w4 · C1 · C2 · C3 · C4 / (gm1 ·
gm2 · gm3 · gm4 · gm11).

Reference numeral 18 denotes a resistor having a resistance value R18. The resistor 18 and one end of a frequency-dependent resistor circuit are connected in series, and a signal is supplied from a terminal 11 connected to the other end of the frequency-dependent resistor circuit. Enter vin. By doing so, the signal vout obtained at the terminal 12 provided at the connection between the frequency-dependent resistor circuit and the resistor is expressed as: vout = {1 / (1 + Zin4 / R18)}. Vin. The signal vout is in phase with the input signal,
And it has a low-pass filter characteristic.

FIG. 6 shows a conventional filtering frequency control device described in Japanese Patent Application No. 63-42724.

[0006] The phase of the input and output of the first resonance circuit is compared, the constant of the first resonance circuit is controlled by the output of the control circuit, and the center frequency of the second resonance circuit is determined.

[0007]

Conventionally, with respect to each element of a capacitor and a resistor constituting a frequency-dependent resistor circuit, the design values thereof actually vary depending on the conditions at the time of manufacture and the like. The value fluctuated depending on the ambient temperature during use. For this reason, the impedance of the frequency-dependent resistance circuit fluctuates or fluctuates due to manufacturing variations and temperature fluctuations.

[0008] Further, since there is almost no phase change in the output of the filter circuit in which the frequency-dependent resistor circuit and the resistor are connected, the signal input from the filter circuit to the signal from the frequency-dependent resistor circuit causes the element of the filter circuit design. Was not able to be constant.

An object of the present invention is to solve the above-mentioned conventional problems, and to provide a frequency control device capable of setting a cut-off frequency of a filter circuit using a frequency-dependent resistance circuit to a stabilized predetermined value. With the goal.

[0010]

According to a first aspect of the present invention, there is provided a frequency adjusting apparatus in which a first circuit and a second circuit each include a capacitor and a resistor. A reference signal having a predetermined frequency is input to the first circuit, and a signal having a different phase is output according to the product of the values of the capacitor and the resistor. A phase error voltage is obtained from the phase difference between the signal and the reference signal. The phase difference is set to a predetermined value according to the value of the phase error voltage and the product of the value of the capacitor and the value of the resistor. This phase error voltage is input to the frequency-dependent resistance circuit, and the impedance of the frequency-dependent resistance circuit varies depending on the value of the phase error voltage and the product of the value of the capacitor and the resistance of the frequency-dependent resistance circuit. A filter circuit is configured by a second circuit in which a resistor is connected to one end of the frequency-dependent resistor circuit. Here, by forming the first and second circuits using the capacitor formed in the same manufacturing process and the resistor formed in the same manufacturing process, the values of the capacitor and the resistance in the first circuit can be reduced. The product can be made to correspond to the product of the value of the capacitor and the value of the resistance in the second circuit. Next, the frequency of the reference signal input to the first circuit and the product of the value of the capacitor and the resistance in the first circuit are made to correspond to each other via the phase error voltage. Can be made to correspond to the frequency of the reference signal input to the first circuit. Here, by using, for example, the output signal of the crystal oscillation circuit as the reference signal, the cutoff frequency of the second circuit can be made equal to the stability of the crystal oscillation circuit. In addition, the same integrated circuit manufacturing process can be realized by adopting a diffusion process for forming an integrated circuit in the first circuit and the second circuit.

In the frequency control apparatus according to a second aspect of the present invention, a capacitor and a resistor are formed by using a diffusion process for forming a semiconductor integrated circuit so that a product of the values of the capacitor and the resistor is constant. The first and second circuits are configured using these elements.

In the first circuit, a current corresponding to the voltage applied to the input terminal pair of the first voltage-current converter is output from the output terminal, and the output terminal of the first voltage-current converter has a reactive property. Connect the load. The voltage generated at this load is input to the second voltage-current converter, and outputs a current from the output unit. The current at the output of the second voltage-to-current converter is input to the first current amplifier, and a signal is externally supplied to the first signal terminal of the first current amplifier. To output a bidirectional current to the output terminal pair.
It is individually applied to an input terminal pair of the first voltage-current converter. In this way, a gyrator circuit whose inductance value is variable according to the signal of the first signal terminal is formed. Here, a gyrator circuit, a capacitor and a resistor are connected in series to form a tuning circuit, and a first signal having a constant frequency is supplied to the tuning circuit. The first signal and a voltage signal generated in the capacitor or the gyrator circuit are input to a phase comparator, and a phase difference between the first signal and the voltage signal is detected. The detected phase difference is output as an error signal and further smoothed by a capacitor. The smoothed voltage is input to a first signal terminal via a control circuit.

When the cutoff frequency of the tuning circuit coincides with the frequency of the first signal, the phase error signal becomes zero because the phase of the first signal and the voltage signal generated in the capacitor or coil are orthogonal. If the off frequency is different from the frequency of the first signal, a phase error signal is generated according to the frequency difference. The cutoff frequency of the tuning circuit is determined by the product of the inductance value of the gyrator circuit and the value of the capacitor. By forming a negative feedback loop so that the error signal becomes zero, the frequency of the first signal is reduced. The product of the value of the capacitor and the value of the inductance can be set to a predetermined value so as to match.

Further, since the inductance value of the gyrator circuit is proportional to the product of the value of the resistor and the value of the capacitor constituting the gyrator circuit, when the negative feedback loop is in a stable state, the product of the value of the capacitor and the value of the resistance becomes a constant value. can do.

In the second circuit, a current corresponding to the voltage applied to the input terminal is applied to the third voltage output from the output terminal.
The circuit has a plurality of circuit units, each unit including a circuit in which a reactive load is connected to an output terminal of the current converter. Here, a plurality of circuit units are connected in cascade, and the output voltage of the circuit unit located at an even number from the first stage is converted into a current, and this current is applied to the input terminal of the first stage circuit unit to form a frequency-dependent resistance circuit. Form. At least one of the current paths of the frequency-dependent resistance circuit further includes a second current amplifier that amplifies a current according to a signal externally applied to the second signal terminal.

Since the output voltage of the control circuit obtained by the first circuit has a function of keeping the product of the value of the capacitor and the resistance constant, the output voltage of the control circuit is reduced by the second voltage of the second circuit. , The product of the value of the capacitor and the resistance of the second circuit can be made constant, and the value of the frequency-dependent resistance circuit is given by the value of the first-order resistance. The cutoff frequency of the filter circuit combining the resistor and the resistor can be made constant according to the frequency of the first signal.

In order to achieve this object, in a frequency control apparatus according to a third aspect of the present invention, a capacitor and a resistor are formed by using a diffusion process for forming a semiconductor integrated circuit. The first and second circuits are configured using these elements so that the product is constant.

In the first circuit, a current is output from an output terminal according to a voltage applied to an input terminal pair of the first voltage-current converter. A reactive load is connected to the output terminal of the first voltage-to-current converter, and the voltage generated at this load is input to the second voltage-to-current converter, and is output from the output section of the second voltage-to-current converter. Outputs current. The current at the output of the second voltage-to-current converter is input to a first current amplifier, and a signal is externally applied to a first signal terminal of the first current amplifier. Thus, a bidirectional current is output. Bidirectional currents are individually applied to the input terminal pairs of the first voltage-to-current converter. In this way, a gyrator circuit whose inductance value is variable according to the signal of the first signal terminal is formed. Here, one end of the gyrator circuit and the first resistor are connected in series, a first signal of a predetermined frequency is input to the gyrator circuit, and the other end of the first resistor is AC grounded to form a phase shift circuit. To extract the phase-shifted signal from the connection. On the other hand, the second,
A third resistor is connected in series, a first signal is input to one end of the second resistor, and one end of the third resistor is AC grounded to form an amplitude attenuating circuit. 1 amplitude from connection
The signal attenuated to / 2 is extracted. The phase-shifted signal and the signal attenuated by 入 力 are input to a subtraction circuit, and a difference signal obtained by vector subtraction is output. This difference signal and the first
Is input to the phase comparator, and the phase difference between the two signals is detected. The detected phase difference is output as an error signal,
Further, it is smoothed by a capacitor. The smoothed voltage is input to a first signal terminal via a control circuit.

In the second circuit, a current corresponding to the voltage applied to the input terminal is applied to the third voltage −
A reactive load is connected to the output terminal of the current converter, and this circuit has a plurality of circuit units as one unit. Here, a plurality of circuit units are cascaded, and the output voltage of the circuit units located at even numbers from the first stage is converted into a current,
This current is applied to the input terminal of the first-stage circuit unit to form a frequency-dependent resistance circuit. At least one of the current paths of the frequency-dependent resistance circuit further includes a second current amplifier that outputs a current amplified according to a signal externally supplied to the second signal terminal. When the cutoff frequency of the phase shift circuit matches the frequency of the first signal, the first
And the phase-shifted signal has a phase of 45 degrees, so that the difference signal and the first signal are orthogonal in phase. When the phases are orthogonal, the phase error signal becomes zero, but if the cutoff frequency and the frequency of the first signal are different, a phase error signal is generated according to the frequency difference. The cutoff frequency of the phase shift circuit is determined by the product of the inductance value of the gyrator circuit and the value of the first resistor. The first signal is formed by forming a negative feedback loop so that the error signal becomes zero. The product of the first resistance and the inductance can be set to a predetermined value so as to match the frequency of Furthermore, since the inductance value of the gyrator circuit is proportional to the product of the value of the resistor and the capacitor that make up the gyrator circuit, when the negative feedback loop is in a stable state, the product of the value of the capacitor and the resistor can be a constant value. it can.

Since the output voltage of the control circuit obtained by the first circuit has a function of keeping the product of the value of the capacitor and the resistance constant, the output voltage of the control circuit is converted to the second voltage of the second circuit. , The product of the value of the capacitor and the resistance of the second circuit can be made constant, and the value of the frequency-dependent resistance circuit is given by a first-order resistor. Can be made constant in accordance with the frequency of the first signal.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a frequency control device according to claim 1 or 2 of the present invention. In FIG. 1, reference numerals 23, 25, and 41 to 45 denote voltage-current converters that convert a voltage applied to a plus input into a current based on a minus input voltage and output the current. When the ratio of the output current to the input voltage is represented by gm, the voltage-current converters 23, 2
5 are gm1 and gm2, and the voltage-current conversions 41 to 45 are gm11 to gm15.
Is defined. The current conversion rate gm is given as the reciprocal of the sum of the emitter resistances of the differential amplifier circuit constituting the voltage-current converter. The reciprocals of gm1, gm2, and gm11 to gm15 are defined as R1, R2, and R11 to R15, respectively. 2
4, 32, 47 to 50 are capacitors. The capacitance value of 24 is defined as C1, the capacitance value of 32 is defined as C2, and the capacitance values of 47 to 50 are defined as C11, C12, C13 and C14. 35 is
This is a smoothing capacitor. 26 and 46 are current amplifiers. The amplification factors of the current amplifiers 26 and 46 are defined as k1 and k2. 36 has a resistance value R36, and 52 has a resistance value R
52. w is the angular frequency of the signal to be handled.

[0023] viewed frequency dependent resistor circuit from the terminal 11 by using the above-defined impedance Zin11 ^{is, Zin11 = k2 · w 4 ·} C11 · C12 · C13 · C14 · R11 · R12 · R13 · R14 · R15 ··· (1) is expressed.

Next, by connecting the resistor 52 and the frequency-dependent resistor circuit in series and inputting the signal vin from the terminal 11, the signal vout obtained at the terminal 12 is as follows: vout = {1 / (1 + Zin11 / R52)}. vin (2) Here, the output vout is determined by the ratio between the impedance Zin11 of the frequency-dependent resistor and the resistor R52.

Next, the impedance Zg when the gyrator circuit is viewed from the terminals 14 and 15 is as follows: Zg = j · k1 · w · C1 · R1 · R2 = j · w · L (3) , L = k1, C1, R1, R2 (4) From this, the impedance Z from the terminal 13 to the ground is: Z = R36 + j · w · L + 1 / jwC2 (5), and the voltage v15 obtained at the terminal 15 is v15 = vin / ｛(1−w ² L · C2) + jwC2 · R36｝ (6)

Here, the voltage of the terminal 15 and the terminal 13 is 90
When a closed loop is formed to have a phase difference of degrees,
In the equation (6), 1−w ² · L · C 2 = 0 (7) holds. The frequency w at this time is defined as w0. From the equations (4) and (7), w0 = (k1, C1, C2, R1, R2) ^-1/2 (8), and the frequency of the signal ^{supplied to} the terminal 13 and the values of the resistor and the capacitor are obtained. It is given via the degree of amplification k1.

The impedance of the frequency-dependent resistance circuit is determined by equation (1) for an arbitrary frequency w. When the frequency of the signal input to the terminal 13 is w0, equation (1) is (8) It is expressed through the equation. Here, if a proportional coefficient 与 え る is given between an arbitrary frequency w and a frequency w0, it can be expressed as w = ψ · w0 (9), and (1), (8), (9) From the equation, the impedance Zin11 of the frequency-dependent resistance circuit is obtained.
Is as follows: Zin11 = (k2 / k1 ² ) · ψ ⁴ · C 11 · C 12 · C 13 · C 14 · R 1 1 · R 12 · R 13 · R 14 · R 15 / (C 1 · C 2 · R 1 · R 2) ² ... (10) Given. Here, the order of the capacitors of the numerator and the denominator is equal, and since the capacitors are manufactured in the same process, the change in the value of the capacitors is the impedance Zin.
11 is not affected. On the other hand, since the resistor is also manufactured in the same process, and the order of the numerator is one order greater than the order of the denominator, the impedance Zin11 varies according to the variation of the resistance or the temperature variation. Here, the amplification degree k1, k
The capacitor C constituting the frequency-dependent resistance circuit is changed by the variation of the diffusion condition or the variation of the temperature by making the ratio of 2 equal.
Even when the values of C11, C12, C13, and C14 fluctuate, a resistor corresponding to the frequency of the signal input to the terminal 13 can be obtained.

A signal obtained by dividing the signal of the terminal 11 by the frequency-dependent resistance circuit and the resistor 52 is output to the terminal 12, and the value of the signal is changed according to the frequency variation from the equations (2) and (10). Different signals are extracted to form a filter circuit.

Here, the frequency when the value of Zin11 is equal to the value of the resistor 52 is defined as a cutoff frequency. The signal taken out at the terminal 12 at this cutoff frequency has a value that is attenuated to half the amplitude of the signal at the terminal 11.

FIG. 2 is a diagram showing an embodiment of the frequency control device according to claim 1 or 3 of the present invention. In FIG. 2, reference numerals 23, 25, and 41 to 45 denote voltage-current converters that convert a voltage applied to a plus input into a current based on a minus input voltage and output the current. When the ratio of the output current to the input voltage is expressed by gm, the voltage-current converters 23, 2
5 are gm1 and gm2, and the voltage-current conversions 41 to 45 are gm11 to gm15.
Is defined. The current conversion rate gm is given as the reciprocal of the sum of the emitter resistances of the differential amplifier circuit constituting the voltage-current converter. The reciprocals of gm1, gm2, and gm11 to gm15 are defined as R1, R2, and R11 to R15, respectively. 2
4, 32, 47 to 50 are capacitors. The capacitance value of 24 is C1, and the capacitance values of 47 to 50 are C11, C12, C1.
3, defined as C14. 35 is a smoothing capacitor. Reference numerals 26 and 46 denote current amplifiers.
The amplification factors of 6, 46 are defined as k1 and k2. 52 is a resistance value R52 and 61 to 63 are resistance values R61 to R63, respectively.
Is a resistance having a value of w is the angular frequency of the signal to be handled. Reference numeral 64 denotes a subtraction circuit that calculates and outputs a difference between two input signals.

The impedance Zin11 viewed frequency dependent resistor circuit from the terminal 11 is expressed as ^{Zin11 = k2 · w 4 · C11} · C12 · C13 · C14 · R11 · R12 · R13 · R14 · R15 ··· (11) You.

Next, by connecting the resistor 52 and the frequency-dependent resistor circuit in series and inputting the signal vin from the terminal 11, the signal vout obtained at the terminal 12 is as follows: vout = {1 / (1 + Zin11 / R52)}. vin (12) The output vout is determined by the ratio between the impedance Zin11 of the frequency dependent resistor and the resistor R52.

Next, the impedance Zg when the gyrator circuit is viewed from the terminals 14 and 15 is as follows: Zg = j · k1 · w · C1 · R1 · R2 = j · w · L (13) where L = k1 · C1 · R1 · R2 (14)

From this, the impedance Z between the terminal 13 and the ground is: Z = R61 + j · w · L (15), and the voltage v65 obtained at the terminal 65 is v65 = vin · R61 / (jwL + R61) (16)

On the other hand, when the values of the resistors 62 and 63 are equal, the voltage v66 obtained at the terminal 66 of the connection portion is as follows: v66 = vin / 2 (17)

Assuming that the voltage difference between the terminal 65 and the terminal 66 is v3, v3 = {R61 / (jwL + R61) -1/2} vin = (R61-jwL) / {2 (jwL + R61)} (18) And the phase is compared with the signal vin of the terminal 13 by the phase comparator 33.

The signal of equation (18) and the voltage at terminal 13 are 90
When a closed loop is formed with a phase difference of degrees,
In equation (18), R61 = | jwL | (19) is satisfied, so the frequency w at this time is defined as w0. From the equations (14) and (19), w0 = R61 / (k1, C1, R1, R2) (20), and the frequency of the signal supplied to the terminal 13 is determined by the values of the resistor and the capacitor and the amplification k1 Given through.

The impedance of the frequency-dependent resistance circuit is
It is determined by equation (11) for an arbitrary frequency w,
When the frequency of the signal input to the terminal 13 is w0,
Equation (11) is expressed via equation (20). Here, if a proportionality coefficient 与 え る is given between an arbitrary frequency w and w0, it can be expressed as w = ψ · w0 (21), and (11), (20), (21)
From the equation, the impedance Zin1 of the frequency-dependent resistance circuit is obtained.
1 is Zin11 = (k2 / k1 ⁴ ) · ψ ⁴ · C 11 · C 12 · C 13 · C 14 · R 1 1 · R 12 · R 13 · R 14 · R 15 · R 61 ⁴ / (C 1 · C 2 · R 1 · R 2) ⁴ ··· (22) given as Here, since the order of the numerator and the denominator of the capacitor is equal and the capacitor is manufactured in the same process, the change in the value of the capacitor is the impedance Zi.
Does not affect n11. On the other hand, the resistance is also manufactured in the same process, but since the order of the numerator is one order greater than the order of the denominator, the impedance Zin11 fluctuates according to resistance variation or temperature fluctuation. Here, the amplification degree k1, k
The capacitor C constituting the frequency-dependent resistance circuit is changed by the variation of the diffusion condition or the variation of the temperature by making the ratio of 2 equal.
Even when the values of C11, C12, C13, and C14 fluctuate, a resistor having a value corresponding to the frequency of the signal input to the terminal 13 can be obtained.

From the equations (12) and (22), a signal which is constant with respect to the change in the value of the resistor and the capacitor and has a different value according to the change in the frequency is extracted from the output of the terminal 12. , A filter circuit can be configured for signals input to

Here, the frequency when the value of Zin11 is equal to the value of the resistor 52 is defined as a cutoff frequency. The signal taken out at the terminal 12 at this cutoff frequency has a value that is attenuated to half the amplitude of the signal at the terminal 11.

FIG. 3 is a diagram showing each signal of FIG. 2 as a vector. The real axis is denoted by Re, and the imaginary axis is denoted by Im. When the signal input to the terminal 13 is given by vin on the real axis, the signal at the terminal 66 is given by ・ · vin, and the signal at the terminal 65 is given by v2. Furthermore, １ ／ for v2
The vector v3 heading from vin is an output signal of the subtractor 64. When the angle between 1.2 · vin and v2 is 45 degrees, vin and v3 are orthogonal.

FIG. 4 is a diagram showing one embodiment of the current amplifier in FIGS. In FIG.
79 is a transistor, 80 and 81 are constant current sources having the same value, 84 and 85 are resistors having the same value, 8
6 and 87 are constant voltage sources, and 100 to 104 are terminals. It is assumed that, for transistors 70 to 79, each base current has a negligible value.

A fixed voltage is applied to the bases of the transistors 70 and 71 by a voltage source 86, and current sources 80 and 81 are connected to the emitter and collector of each transistor. Transistors 72 and 73 form a differential transistor pair. The base of transistor 72 is connected to the emitter of transistor 70, while the base of transistor 73 is connected to the emitter of transistor 71. The emitters of the transistors 72 and 73 are connected to the collectors of the transistors 74 and 75, respectively.
A voltage is applied to the bases of 4, 75 from a terminal 104,
Resistor 84 connected between transistors 74 and 75 and ground
As a result, the voltage at the terminal 104 is converted into a current to form emitter currents of the transistors 72 and 73. Further, the collector of the transistor 72 is connected to the collector of the transistor 77, and the collector of the transistor 73 is connected to the collector of the transistor 78. Also, terminal 10
4 applies a voltage to the base of a transistor 76, and a resistor 8 connected between the emitter of this transistor and ground.
5 is converted to a current. The collector of the transistor 76 is connected to the collector and base of the transistor 79 and the bases of the transistors 77 and 78 to form a mirror circuit. Through this mirror circuit, the current of the resistor 85 is supplied from the collectors of the transistors 77 and 78 to the collectors of the transistors 72 and 73, respectively. still,
The voltage of voltage source 87 is applied to the emitters of transistors 77 to 79. Here, the sum of the collector currents of the transistors 77 and 78 is equal to the sum of the collector currents of the transistors 74 and 75.

Next, the emitter of the transistor 70 is connected to the terminal 100, and the emitter of the transistor 71 is connected to the terminal 101. An alternating current is applied between the terminals 100 and 101. A terminal 102 is connected to the collectors of the transistors 72 and 77, and a terminal 103 is connected to the collectors of the transistors 73 and 78, so that an alternating current is taken out between the two terminals. The amplification of this alternating current is
DC current values of current sources 80 and 81 and transistors 74 and 7
5 and the current ratio of the DC current formed by the resistor 84. This ratio differs depending on the voltage applied to the terminal 104.

When the current amplifier of FIG. 4 is used as the current amplifier of FIGS. 1 and 2, the output voltage of the control circuit 34 is applied to the terminal 104 to amplify the bidirectional AC current applied to the terminals 100 and 101. And can be taken out from the terminals 102 and 103.

[0046]

According to the present invention, there is provided a frequency adjusting device including a capacitor and a resistor, which receives a reference signal of a predetermined frequency, outputs a signal having a phase corresponding to a product of the values of the capacitor and the resistor, and outputs a signal having a phase corresponding to the product of the reference signal. First to generate control voltage from phase difference
And a second circuit in which a resistor is connected to a frequency-dependent resistor circuit that receives the control voltage and has a different frequency characteristic according to the product of the control voltage value and the value of the capacitor and the resistor. By forming the capacitor and the resistor of the second circuit and the capacitor of the second circuit in the same integrated circuit manufacturing process, the impedance of the frequency-dependent resistor circuit can be set to a predetermined value of the dimension of the resistor. The cutoff frequency of the filter circuit including the circuit and the resistor as components can correspond to the reference signal.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a frequency control device according to claim 1 or 2 of the present invention.

FIG. 2 is a diagram showing an embodiment of a frequency control device according to claim 1 or 3 of the present invention.

FIG. 3 is a diagram showing each signal of FIG. 2;

FIG. 4 is a circuit diagram showing an embodiment of the current amplifier in FIG. 1 or 2;

FIG. 5 is a diagram showing a filter device using a conventional frequency-dependent resistance circuit.

FIG. 6 is a diagram showing a conventional filtering frequency control device.

[Explanation of symbols]

 1-5 Voltage-current converter 7-10 Capacitor 11-15 Terminal 18 Resistance 20 First circuit 21 Second circuit 23 Voltage-current converter 24 Capacitor 25 Voltage-current converter 26 Current amplifier 32 Capacitor 33 Phase comparison Device 34 control circuit 35 capacitor 41-45 voltage-current converter 46 current amplifier 47-50 capacitor 52 resistor 61-63 resistor 64 subtractor 65, 66 terminal 70-79 transistor 80, 81 current source 84, 85 resistor 86, 87 Voltage source 100 to 104 terminals

Claims (3)

[Claims] 1. A frequency adjusting device having a capacitor and a resistor, wherein a reference signal having a predetermined frequency is input, and a signal having a phase corresponding to a product of the values of the capacitor and the resistor is output to output a signal having a phase corresponding to the reference signal. Generate a phase error voltage from the phase difference,
A first circuit for setting the phase difference to a predetermined value in accordance with a product of the value of the phase error voltage and the value of the capacitor and the resistor; a phase error voltage input thereto; And a second circuit in which a resistor is connected to one end of a frequency-dependent resistor circuit having a different impedance depending on the product of the values of the first and second circuits, and the capacitors and the resistors of the first circuit and the second circuit are formed in the same process. A frequency adjustment device characterized by the above-mentioned. 2. A frequency adjusting device in which a plurality of capacitors and resistors are formed in the same integrated circuit manufacturing process, wherein a current corresponding to a voltage applied to an input terminal pair is output from an output terminal. A voltage-current converter, a reactive load connected to an output terminal of the first voltage-current converter,
A second voltage-current converter that receives a voltage generated in the reactive load and outputs a current from an output unit; and a second voltage-current converter having a first signal terminal to which a signal is externally supplied.
A first current amplifier that inputs an output current of the current converter and outputs a current having a different value in both directions to an output terminal pair in accordance with a signal of the first signal terminal; and an output terminal pair of the first current amplifier. A tuning circuit in which a capacitor and a resistor are connected in series to one end of a gyrator circuit having means for individually connecting an input terminal pair of a first voltage-current converter, and a first signal is supplied to the tuning circuit. A voltage comparator and a first signal that are individually input to a pair of input terminals, a phase difference is detected and a phase error signal is output to an output terminal, and the phase error signal is input to the input terminal pair. A control circuit that outputs a smoothed voltage signal, and a circuit unit in which a reactive load is connected to an output terminal of a third voltage-current converter that outputs a current corresponding to a voltage applied to an input terminal from an output terminal. Are connected in cascade, an output voltage of a circuit unit located at an even-numbered position from the first stage is converted into a current, and a frequency-dependent resistance circuit for applying this current to an input terminal of the first-stage circuit unit; A second current amplifier that includes a second signal terminal and amplifies a current in accordance with a signal of the second signal terminal in at least one of the current paths of the frequency-dependent resistance circuit; A frequency adjusting device for inputting a signal to first and second signal terminals. 3. A frequency adjusting device in which a plurality of capacitors and resistors are formed in the same integrated circuit manufacturing process, wherein a current corresponding to a voltage applied to an input terminal pair is output from an output terminal. A voltage-current converter, a reactive load connected to an output terminal of the first voltage-current converter,
A second voltage-current converter that receives a voltage generated in the reactive load and outputs a current from an output unit; and a second voltage-current converter having a first signal terminal to which a signal is externally supplied.
A first current amplifier that inputs an output current of the current converter and outputs a current having a different value in both directions to an output terminal pair in accordance with a signal of the first signal terminal; and an output terminal pair of the first current amplifier. A phase shift circuit for connecting a resistor in series to one end of a gyrator circuit including means for individually connecting an input terminal pair of the first voltage-current converter and extracting a signal from the connection; A third resistor connected in series, an attenuating circuit for extracting a signal from the connection, and a signal at a connection between the phase shifter and the attenuator are individually input, and a phase difference between the two signals is compared. A control circuit that smoothes the phase error signal and outputs a voltage signal; and a third voltage-current converter that outputs a current corresponding to a voltage applied to an input terminal from an output terminal. Is connected to a reactive load. A plurality of circuit units are connected in cascade, an output voltage of a circuit unit located at an even-numbered position from the first stage is converted into a current, and this current is supplied to an input terminal of the first-stage circuit unit. A second signal terminal to which a signal is applied; and a second current amplifier in at least one of the current paths of the frequency-dependent resistance circuit and amplifying a current according to a signal of the second signal terminal. A frequency adjusting device for inputting a voltage signal of a control circuit to first and second signal terminals.