JPH08181570A - Phase shifter - Google Patents

Abstract

PURPOSE: To increase the phase shift amount per one stage while changing only the phase without attenuation in a signal amplitude. CONSTITUTION: The phase shifter 100 is provided with an operational amplifier 10, a resistor 12 and a capacitor 14 lagging the phase of a signal received by an input terminal 20 and giving the resulting signal to a noninverting input terminal of the operational amplifier 10, an input resistor 16 inserted between the input terminal 20 and an inverting input terminal of the operational amplifier 10, and a feedback resistor 18 inserted between an output terminal of the operational amplifier 10 and the inverting input terminal. When the gain of the operational amplifier 10 is set to 1 and the resistance of the resistors 16, 18 is selected identical, a signal with a phase lag angle twice the phase lag angle by the resistor 12 and the capacitor 14 is outputted from the operational amplifier 10 and no attenuation is caused between the input signal and the output signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an all-pass type phase shifter used for a phase shift oscillator or the like.

[0002] In this specification, when the phase of the input signal is used as a reference, the case where the phase of the output signal advances by up to 180 ° is "advanced type", and the phase of the output signal is 18 degrees.
The case where there is a delay within the range of 0 ° will be referred to as a “phase delay type” for explanation.

[0003]

2. Description of the Related Art Conventionally, there has been known a phase shift oscillator that oscillates by setting the phase of a signal that makes a round through a feedback loop to 0 ° or 360 ° and setting the loop gain to 1 or more. This phase-shift oscillator is composed of, for example, a portion that performs inverting amplification and a portion that rotates the phase shift. Has become.

FIG. 18 is a diagram showing an example of a configuration for rotating a phase shift used in the above-mentioned phase shift oscillator or the like. FIG. 3A shows a configuration in which CR high pass filters are connected in three stages. A 1-stage CR high-pass filter can theoretically shift the phase by up to 90 ° when the frequency is infinite, but it is not practical to operate at such a frequency, so in practice, 3 stages are connected to form an overall filter. As 180 °
The phase shift is performed (60 ° per stage).

Further, FIG. 1B shows a configuration in which CR low-pass filters are connected in three stages. Similar to the case of the high-pass filter, the one-stage CR low-pass filter can theoretically shift the phase by up to 90 ° when the frequency is infinite, but in reality, three stages are connected to make a total of 180 degrees.
° It is designed to perform a phase shift.

The phase shift amount is 90 ° or 18
If it is less than 0 °, C of 1 or 2 steps
It is also possible to shift the phase shift with an R high-pass filter or a low-pass filter.

[0007]

By the way, the above-mentioned C
R high-pass filter or low-pass filter,
Since the signal is attenuated at the same time as the phase is shifted, there is a problem when it is used for the purpose of shifting the phase. Therefore, for example, when it is used for a phase shift oscillator, the attenuation is compensated by setting a large amplification factor of the inverting amplifier.

Further, since the amount of attenuation of the signal also changes according to the amount of phase shift, that is, the amount of attenuation of the signal amplitude also changes according to the frequency of the input / output signal, the amount of phase shift can be set to any desired amount. When it is used as a container, an additional circuit for stabilizing the signal amplitude is required, which is inconvenient.

Further, considering the amount of signal attenuation, the amount of phase shift by the filter per stage could not be set too large. Therefore, there has been a situation in which the number of stages of filters to be connected has to be changed for each required phase shift amount.

The present invention has been made in view of the above points, and its purpose is to change only the phase without attenuation of the signal amplitude and to have a large amount of phase shift per stage. To provide a container.

[0011]

In order to solve the above-mentioned problems, a phase shifter according to a first aspect of the invention has a first resistor connected to an inverting input terminal, and the inverting input terminal inverts the first resistor via the first resistor. A first operational amplifier having an input signal input to the input terminal, a second resistor connected between the inverting input terminal and the output terminal of the first operational amplifier, a third resistor and a capacitor. And a serial circuit that divides the voltage of the input signal applied to both ends and applies the divided voltage to the non-inverting input terminal of the first operational amplifier.

A phase shifter according to a second aspect is the phase shifter according to the first aspect, wherein the third resistor in the series circuit is connected to the first resistor, and the phase of the input signal is delayed by a predetermined angle. It is characterized by outputting as.

A phase shifter according to a third aspect is the phase shifter according to the first aspect, wherein the capacitor in the series circuit is connected to the first resistor, and the phase of the input signal is advanced by a predetermined angle to be output. It is characterized by doing.

A phase shifter according to a fourth aspect is the phase shifter according to any one of the first to third aspects, wherein the phase shift amount is changed by changing the resistance value of the third resistor. Characterize.

A phase shifter according to a fifth aspect is the phase shifter according to any one of the first to third aspects, wherein the capacitance of the capacitor is changed to change the total phase shift amount. To do.

A phase shifter according to a sixth aspect is the phase shifter according to any one of the first to third aspects, in which the resistance of the third resistor and the capacitance of the capacitor are changed to change the overall phase. The feature is that the shift amount is changed.

A phase shifter according to a seventh aspect is the phase shifter according to the fourth or sixth aspect, wherein the third resistor is formed by a channel of a field effect transistor, and a gate voltage is changed to change a channel resistance. , The total amount of phase shift is changed.

The phase shifter according to claim 8 is the phase shifter according to claim 5 or 6, wherein the capacitor is formed by a variable capacitance diode, and the reverse bias voltage applied between the anode and the cathode is changed to change the electrostatic capacitance. By changing,
It is characterized in that the entire phase shift amount is changed.

According to a ninth aspect of the present invention, in the phase shifter according to any one of the first to third aspects, the capacitor is an amplifier having a predetermined gain and a capacitor connected in parallel between the input and output of the amplifier. And an element, and the capacitance viewed from the input side of the amplifier is different from the capacitance actually possessed by the capacitor element.

According to a tenth aspect of the present invention, in the phase shifter of the ninth aspect, by setting the gain of the amplifier to a negative value, the capacitance seen from the input side of the amplifier is actually the capacitor. It is characterized in that the capacitance is larger than the capacitance of the element.

The phase shifter of claim 11 is the phase shifter of claim 9, wherein the gain of the amplifier is set between 0 and 1 so that the capacitance viewed from the input side of the amplifier is actually achieved. The capacitance is smaller than the capacitance of the capacitor element.

The phase shifter of claim 12 is the phase shifter of claim 9 or 1.
In the phase shifter of 0, the amplifier has a second operational amplifier whose non-inverting input terminal is connected to a fixed potential and whose output terminal is connected to one end of the capacitor element, and the other end of the capacitor element and A fourth resistor inserted between the inverting input terminal of the second operational amplifier and a fifth resistor inserted between the output terminal and the inverting input terminal of the second operational amplifier. , And operates as an inverting amplifier with a negative gain.

According to a thirteenth aspect of the present invention, in the phase shifter of the twelfth aspect, a buffer is further provided between the other end of the capacitor element and the fourth resistor before the amplifier. It is characterized by increasing the input impedance.

According to a fourteenth aspect of the present invention, in the phase shifter according to the thirteenth aspect, the buffer has a non-inverting input terminal connected to the other end of the capacitor element and an output terminal connected to the fourth terminal.
A third operational amplifier connected to the resistor and a sixth resistor connected between the output terminal and the inverting input terminal of the third operational amplifier.

According to a fifteenth aspect of the present invention, in the phase shifter according to the thirteenth aspect, the buffer comprises an emitter follower circuit or a source follower circuit.

The phase shifter of claim 16 is the phase shifter of claims 12-15.
In any one of the above phase shifters, at least one of the fourth, fifth, and sixth resistors is formed by a variable resistor to change the capacitance of the capacitor and change the overall phase shift amount. It is characterized by

The phase shifter of claim 17 is the phase shifter of claim 9 or 1.
In one phase shifter, the amplifier comprises two non-inverting amplifiers arranged in series and a first voltage dividing circuit connected between the two non-inverting amplifiers, and the overall gain is It is characterized in that it is set between 0 and 1 according to the voltage dividing ratio of the first voltage dividing circuit.

The phase shifter of claim 18 is the phase shifter of claim 9 or 1.
In the phase shifter of No. 1, the amplifier has a second
Is formed by an emitter follower circuit to which the voltage dividing circuit is connected or a source follower circuit to which a second voltage dividing circuit is connected on the source side. By extracting an output from the second voltage dividing circuit, the total gain is increased. Is set between 0 and 1 according to the voltage dividing ratio of the second voltage dividing circuit.

According to a nineteenth aspect of the present invention, in the phase shifter according to the seventeenth or eighteenth aspect, the voltage dividing circuit is formed to include a variable resistor so that the capacitance of the capacitor can be varied and the total voltage can be changed. It is characterized in that the amount of phase shift is changed.

A phase shifter according to a twentieth aspect is the phase shifter according to the sixteenth aspect or the nineteenth aspect, in which the resistance value of the third resistor included in the series circuit is changed and the capacitance of the capacitor is changed. By doing so, the entire phase shift amount is changed.

A phase shifter according to a twenty-first aspect is the phase shifter according to the twentieth aspect, wherein the third resistance is formed by a channel of a field effect transistor, and the gate voltage is changed to change the channel resistance, whereby It is characterized in that the phase shift amount of is changed.

According to a twenty-second aspect of the present invention, the phase shifter according to any one of the first to twenty-first aspects is characterized in that the constituent parts are integrally formed on a semiconductor substrate.

[0033]

According to the first aspect of the present invention, the input signal is divided by the third resistor and the capacitor and is input to the non-inverting input terminal of the first operational amplifier, and also via the first resistor. It is input to the inverting input terminal. A second resistor is connected between the output terminal and the inverting input terminal of this operational amplifier. Considering an ideal operational amplifier, since no potential difference is generated between the inverting input terminal and the non-inverting input terminal, the third resistor having the first resistor connected at one end is connected to the third resistor connected at one end. The same voltage appears as the voltage appearing across either one of the resistance or the capacitor. Moreover, when the first and second resistors having substantially the same resistance value are connected to an ideal operational amplifier, a common current flows through these two resistors, so that the first resistor is also applied to both ends of the second resistor.
Almost the same voltage appears across the resistance of the resistor. Therefore, a phase difference of about twice the phase angle shifted by the third resistor and the capacitor occurs between the input and output signals, and a large amount of phase shift can be set.

When the amplitude of the input / output signal is considered with reference to the inverting input terminal of the operational amplifier, the voltage at which the input signal appears across the first resistor is added to the voltage at the inverting input terminal in a vector manner. In that case, the output signal vector-wise subtracts the voltage appearing across the second resistor from the voltage at the inverting input terminal, so that the amplitudes of the input signal and the output signal are equal and the phase shift is By doing so, no signal attenuation occurs.

According to a second aspect of the present invention, the first resistor and the third resistor are connected to each other, and the input signal is divided by the series circuit including the third resistor and the capacitor.
A signal whose phase is delayed with respect to the input signal is input to the non-inverting input terminal of the operational amplifier. Therefore, a delay type phase shifter having a phase shift amount twice this phase can be easily realized.

According to a third aspect of the present invention, the first resistor and the capacitor are connected to each other, and the input signal is divided by the series circuit including the third resistor and the capacitor.
A signal whose phase is advanced with respect to the input signal is input to the non-inverting input terminal of the operational amplifier. Therefore, it is possible to easily realize a phase advance type phase shifter having a phase shift amount twice this phase.

According to the invention of claim 4, the phase shift amount can be easily changed by changing the resistance value of the third resistor which constitutes the series circuit. Similarly, in the invention of claim 5, the amount of phase shift can be easily changed by changing the capacitance of the capacitor forming the series circuit.

According to the sixth aspect of the present invention, the phase shift amount can be easily changed by changing both the resistance value of the third resistor and the electrostatic capacitance of the capacitor which form the series circuit. it can.

According to the invention of claim 7, the third resistance whose resistance value can be changed is specifically formed by the channel of the field effect transistor, and the third resistance can be easily changed only by changing the gate voltage. The resistance value of the resistor can be changed.

According to the eighth aspect of the present invention, the capacitance variable capacitor is specifically formed by a variable capacitance diode, and the capacitance can be easily changed only by changing the reverse bias voltage applied. .

The invention of claim 9 discloses another example of a capacitor, which has a configuration in which a capacitor element having a predetermined electrostatic capacity and an amplifier are connected in parallel. When the capacitance of the capacitor element is C0 and the transfer function of the amplifier is K, this configuration is converted based on Miller's theorem. From the input side of the amplifier, the capacitance of the converted configuration is (1-K). It becomes C0. Therefore, the apparent electrostatic capacitance can be made different from the actual electrostatic capacitance C0 according to the transfer function K, that is, the gain of the amplifier, and the small electrostatic capacitance can be made to appear apparently large. In particular, in the case where the entire phase shifter is integrated on the semiconductor substrate, only a small capacitor element can be formed on the semiconductor substrate. Therefore, if a small capacitance can be converted into a large capacitance, it is necessary for integration. It is particularly convenient, and there is also an effect of cost reduction by reducing the mounting area.

The invention of claim 10 or 11 specifically shows the gain of the amplifier when the electrostatic capacitance is changed. That is, the apparent capacitance is (1-
K) C0, so by setting the gain K of the amplifier to a negative value, the gain of the amplifier is changed from 0 to 1 by increasing C0.
It is possible to change C0 to the smaller one by setting it during the period.

According to the twelfth aspect of the present invention, the amplifier according to the ninth or tenth aspect of the invention is specifically configured by an inverting amplifier using an operational amplifier, and the gain of the amplifier can always be negative. In the invention of claim 13, the input impedance can be increased by inserting a buffer on the input side of the operational amplifier. In the invention of claim 14 or 15, the buffer is formed by using an operational amplifier, or an emitter follower circuit or a source follower circuit is used. It can be easily configured by a circuit.

According to the sixteenth aspect of the present invention, the amplification factor of the inverting amplifier can be varied by configuring the resistance constituting the inverting amplifier together with the above-mentioned operational amplifier with a variable resistor, whereby the apparent static voltage can be changed. By continuously changing the capacitance, the phase shift amount of the entire phase shifter can also be continuously changed.

The invention according to claim 17 or 18 is
Specifically, the amplifier according to the invention of claim 9 or 11 is configured by two non-inverting amplifiers or an emitter follower circuit, a source follower circuit, and a voltage divider circuit. It can be set to 1 to change the apparent capacitance to be smaller than C0.

According to the nineteenth aspect of the present invention, the overall gain can be varied by configuring the resistor forming the above voltage dividing circuit by a variable resistor, whereby the apparent capacitance is also continuous. The phase shift amount of the entire phase shifter can be continuously converted.

According to the twentieth aspect of the present invention, the capacitance of the capacitor included in the series circuit described above is changed, and the resistance value of the third resistor is also changed. By changing it, the phase shift amount can be easily changed. The invention of claim 21 is
This third resistance whose resistance value can be changed is specifically formed by the channel of the field effect transistor, and the resistance value of the third resistance can be easily changed only by changing the gate voltage.

According to the twenty-second aspect of the present invention, the entire phase shifter is integrally formed on the semiconductor substrate, so that the circuit can be downsized and the manufacturing cost can be reduced by the integration.

[0049]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A phase shifter of an embodiment to which the present invention is applied will be specifically described below with reference to the drawings.

[First Embodiment] FIG. 1 is a diagram showing a circuit configuration of a delay type phase shifter 100 of the first embodiment. As shown in the figure, the phase shifter 100 of the first embodiment includes an operational amplifier (operational amplifier) 10 and a resistor for delaying the phase of the signal input to the input terminal 20 and inputting the signal to the non-inverting input terminal of the operational amplifier 10. 12 and the capacitor 14, and the input terminal 20
Between the input resistor 16 and the inverting input terminal of the operational amplifier 10 and the output terminal of the operational amplifier 10 (the phase shifter 10
It is configured to include a feedback resistor 18 inserted between an output terminal 22 of 0) and an inverting input terminal.

The phase shifter 100 of the first embodiment has such a structure, and its operation will be described below.

When an input signal is input to the input terminal 20,
A voltage obtained by dividing the voltage (input voltage) Ei applied to the input terminal 20 by the resistor 12 and the capacitor 14 is applied to the non-inverting input terminal of the operational amplifier 10.

Further, since there is no potential difference between the two inputs (the inverting input terminal and the non-inverting input terminal) of the operational amplifier 10 shown in FIG. 1, the potential of the inverting input terminal of the operational amplifier 10,
The potential at the connection point between the resistor 12 and the capacitor 14 becomes equal. Therefore, the same voltage VR1 as the voltage VR1 appearing across the resistor 12 appears across the input resistor 16.

Here, when the operational amplifier 10 operates ideally and the resistance values of the resistors 16 and 18 are equal, the same current flows through these two resistors 16 and 18, so that both ends of the resistor 18 are also connected. The voltage VR1 appears. Moreover,
The voltage VR1 appearing across each of these two resistors 16 and 18
Have the same direction in terms of vector, and considering the inverting input terminal (voltage VC1) of the operational amplifier 10 as a reference, the vector addition of the voltage VR1 of the resistor 16 is added to the input voltage Ei of the resistor 18. The output voltage Eo is obtained by vectorally subtracting the voltage VR1.

FIG. 2 is a vector diagram showing the relationship between the input / output voltage of the phase shifter and the voltage appearing at the capacitor or the like.

As shown in the figure, the voltage VC1 appearing across the capacitor 14 and the voltage VR1 appearing across the resistor 12 are 90 ° out of phase with each other, and the vector addition of these results in the input voltage Ei. Becomes Therefore, when the amplitude of the input signal is constant and only the frequency changes,
The voltage VC1 across the capacitor 14 and the voltage VR1 across the resistor 12 change along the circumference of the semicircle shown in FIG.

The output voltage Eo is obtained by subtracting the voltage VR1 from the voltage VC1 in vector. Considering the voltage VC1 of the inverting input terminal as a reference, the input voltage Ei and the output voltage E
Only o differs from o in the direction in which the voltage VR1 is combined, and their absolute values are equal. Therefore, the relationship between the magnitude and the phase of the input / output voltage can be expressed by an isosceles triangle having the input voltage Ei and the output voltage Eo as hypotenuses and the base being twice the voltage VR1. The amplitude of the output signal is related to the frequency. The same as the amplitude of the input signal, but the phase shift amount is -φ (φ>
It can be seen that it is 0).

As is clear from FIG. 2, the voltage VC1
And the voltage VR1 intersect at a right angle on the circumference, theoretically, the phase difference between the input voltage Ei and the voltage VC1 changes from 0 ° to 90 ° as the angular velocity ω changes from 0 to ∞. Since the phase shift amount φ of the entire phase shifter 100 is twice that, it changes from 0 ° to 180 ° depending on the frequency.

Next, the relationship between the input and output voltages described above will be verified quantitatively.

As described above, since there should be no potential difference between the two inputs (the inverting input terminal and the non-inverting input terminal) of the operational amplifier 10 shown in FIG.
The voltage VR1 generated across the input resistance 16 and the voltage generated across the input resistor 16 (having a resistance value r) are equal. Therefore, if the current flowing through the input resistor 16 is i,

[Equation 1]

[Equation 2] Or

(Equation 3) Is established. The expression (2) or the expression (3) is derived assuming that the resistance value of the feedback resistor 18 is equal to the resistance value r of the input resistor 16.

Since the voltage Ei of the input signal is divided by the series circuit of the resistor 12 and the capacitor 14, the resistance value of the resistor 12 is R and the electrostatic capacity of the capacitor 14 is C, and both ends of the resistor 12 are defined. When the voltage VR1 appearing at

[Equation 4] Becomes From equations (3) and (4),

(Equation 5) Becomes Substituting s = jω in the equation (5) and transforming it,

(Equation 6) Becomes When the absolute value of the output voltage Eo is calculated from the equation (6),

(Equation 7) Becomes That is, the expression (7) is obtained by the phase shifter 10 of the present embodiment.
The value 0 indicates that the amplitude of the output signal is equal to the amplitude of the input signal and is constant no matter how the phase between the input and the output is rotated.

Further, when the phase shift amount φ of the output voltage Eo with respect to the input voltage Ei is obtained from the equation (6),

(Equation 8) Becomes From the equation (8), the phase shift amount φ is 90 ° at the frequency where ω = 1 / (RC), for example.

In this way, the phase shifter 100 of this embodiment is
Only the phase can be delayed without attenuating the input signal. Moreover, the amount of phase shift at this time is
It is possible to realize the phase shifter 100 that is set in a range of up to 180 ° and has a large amount of phase shift per stage.

[Second Embodiment] The phase shifter 100 of the first embodiment described above delays the phase of the output signal with respect to the input signal in the range of 0 ° to 180 °.
The phase shifter of the second embodiment is characterized by advancing the phase of the output signal with respect to the input signal in the range of 0 ° to 180 °.

FIG. 3 shows a phase advance type phase shifter 20 of the second embodiment.
It is a figure which shows the circuit structure of 0. As shown in FIG.
The phase shifter 200 according to the embodiment advances the phase of the signal input to the operational amplifier 30 and the input terminal 20, and the operational amplifier 30.
Of the capacitor 32 and the resistor 34, which are input to the non-inverting input terminal of the operational amplifier 30, the input resistor 36 inserted between the input terminal 20 and the inverting input terminal of the operational amplifier 30, and the output terminal of the operational amplifier 30 (the output terminal of the phase shifter 200). 22) and a feedback resistor 38 inserted between the inverting input terminal and the inverting input terminal.

The phase shifter 200 of the second embodiment has such a structure, and its operation will be described below.

When an input signal is input to the input terminal 20,
A voltage obtained by dividing the input voltage Ei applied to the input terminal 20 by the capacitor 32 and the resistor 34 is applied to the non-inverting input terminal of the operational amplifier 30.

Further, since there is no potential difference between the two inputs (the inverting input terminal and the non-inverting input terminal) of the operational amplifier 30 shown in FIG. 3, the potential of the inverting input terminal of the operational amplifier 30,
The potential at the connection point between the capacitor 32 and the resistor 34 becomes equal. Therefore, the same voltage VC2 that appears across the capacitor 32 appears across the input resistor 36.

Here, when the operational amplifier 10 operates ideally and the resistance values of the resistor 36 and the resistor 38 are equal, the same current flows through these two resistors 36, 38, so that both ends of the resistor 38 also. The voltage VC2 appears. Moreover,
The voltage VC2 appearing across each of these two resistors 36, 38
Are vectorally oriented in the same direction. Considering the inverting input terminal (voltage VR2) of the operational amplifier 30, the voltage VC2 across the resistor 36 is added vectorically to the input voltage Ei and the resistor 38. The output voltage Eo is obtained by subtracting the voltage C2 in vector.

FIG. 4 is a vector diagram showing the relationship between the input / output voltage of the phase shifter of this embodiment and the voltage appearing at the capacitor or the like.

As shown in the figure, the voltage VR2 appearing across the resistor 34 and the voltage VC2 appearing across the capacitor 32 are 90 ° out of phase with each other, and the vector addition of these results in the input voltage Ei. Becomes Therefore, when the amplitude of the input signal is constant and only the frequency changes,
Along the circumference of the semicircle shown in FIG.
And the voltage VC2 across the capacitor 32 change.

The output voltage Eo is obtained by subtracting the voltage VC2 from the voltage VR2 in a vector manner. Considering the voltage VR2 at the inverting input terminal as a reference, the input voltage Ei and the output voltage E
Only o is different from o in the direction in which the voltage VC2 is combined, and their absolute values are equal. Therefore, the relationship between the magnitude and phase of the input / output voltage can be expressed by an isosceles triangle whose hypotenuse is the input voltage Ei and output voltage Eo and whose base is twice the voltage VC2, and the amplitude of the output signal is related to the frequency. It can be seen that the amplitude is the same as that of the input signal and the phase shift amount is φ ′.

As is clear from FIG. 4, the voltage VR2
And the voltage VC2 intersect at a right angle on the circumference, theoretically, the phase difference between the input voltage Ei and the voltage VR2 changes from 90 ° to 0 ° as the angular velocity ω changes from 0 to ∞. The shift amount φ ′ of the entire phase shifter 200 is 2
Since it is double, it changes from 180 ° to 0 ° depending on the frequency.

Next, the relationship between the input and output voltages described above will be verified quantitatively.

As described above, the operational amplifier 30 shown in FIG. 3 operates so that no potential difference is generated between the two inputs (the inverting input terminal and the non-inverting input terminal), so that the capacitor 32 is operated.
The voltage VC2 across the input resistor 36 and the voltage across the input resistor 36 are equal. Therefore, if i flows through the input resistor 36,

[Equation 9]

[Equation 10] Or

[Equation 11] Is established. In addition, the expression (10) or the expression (11) is
It is derived assuming that the resistance value of the feedback resistor 38 is equal to the resistance value r of the input resistor 36.

The voltage Ei of the input signal is applied to the capacitor 3
Since the voltage is divided by the series circuit of 2 and the resistor 34, the voltage VC2 appearing across the capacitor 32 is calculated as follows.

(Equation 12) Becomes From equations (11) and (12),

(Equation 13) Becomes Substituting s = jω in this equation (13) and transforming it,

[Equation 14] Becomes The expression (14) differs from the expression (6) shown in the first embodiment only in the sign. Therefore, for the absolute value of the output voltage Eo, the equation (7) can be applied as it is, and the phase shifter 200 of the second embodiment can output the amplitude of the output signal no matter how the phase between the input and the output rotates. It can be seen that is constant and equal to the amplitude of the input signal.

Further, when the phase shift amount of the output voltage Eo with respect to the input voltage Ei is calculated,

(Equation 15) Becomes Therefore, for example, the phase shift amount φ ′ at the frequency where ω = 1 / (RC) is 90 °.

In this way, the phase shifter 200 of this embodiment is
Only the phase can be advanced without attenuating the input signal. Moreover, the amount of phase shift at this time is
It is possible to realize the phase shifter 200 which is set in a range up to 180 ° and has a large amount of phase shift for one stage.

[Other Embodiments] Next, other embodiments in which the phase shifter of each of the above-described embodiments is modified will be described.

In the phase shifters 100 and 200 of the respective embodiments shown in FIG. 1 or 3, a constant amount of phase shift determined by the element constants of the resistor 12 and the capacitor 14 or the capacitor 32 and the resistor 34 is set. , The amount of phase shift is fixedly determined for a certain frequency. Therefore, if the element constant of the resistor or the capacitor described above can be changed, the amount of phase shift can be changed arbitrarily.

FIG. 5 is a diagram showing the structure of a phase-shifter of the slow phase type in which the amount of phase shift can be continuously changed by using a variable resistor. The phase shifter 100 of the first embodiment is shown in FIG. It corresponds.

The phase shifter 100a shown in FIG.
The resistance 12 of the phase shifter 100 shown in FIG. 2 is replaced by a variable resistance 12a. By continuously changing the resistance value of the variable resistance 12a, the phase shift amount of the entire phase shifter 100a is also continuous. Changes to. That is, when the resistance value of the variable resistor 12a increases, the variable resistor 12a and the capacitor 1
Since the potential of the connection point 4 moves clockwise on the circumference shown in FIG. 2, the phase shift amount φ of the entire phase shifter 100a continuously increases accordingly. On the contrary, the variable resistance 12
When the resistance value of a decreases, the potential at the connection point between the variable resistor 12a and the capacitor 14 moves counterclockwise on the circumference shown in FIG. 2, and accordingly, the phase shift amount of the entire phase shifter 100a. φ also decreases continuously.

Also, the phase shifter 100b shown in FIG.
More specifically has a configuration in which the variable resistor 12a is replaced with a MOS type or junction type FET 12b.
By using the channel of the FET 12b as a resistor and variably controlling the gate voltage to change the channel resistance, the phase shift amount of the entire phase shifter 100b can be continuously changed.

The phase shifter 100b shown in FIG.
In the above, the variable resistance is constituted by the p-channel or n-channel FET 12b.
The variable resistor may be configured by a transmission gate in which T and an n-channel FET are connected in parallel.

Similarly, FIG. 6 is a diagram showing the construction of a phase-advancing type phase shifter in which the amount of phase shift can be continuously changed by using a variable resistor. The phase shifter of the second embodiment is shown in FIG. It corresponds to 200.

The phase shifter 200a shown in FIG.
The resistance 34 of the phase shifter 200 shown in FIG. 2 is replaced with a variable resistance 34a. By continuously changing the resistance value of the variable resistance 34a, the phase shift amount of the entire phase shifter 200a is also continuously changed. Changes to. That is, when the resistance value of the variable resistor 34 a increases, the capacitor 32 and the variable resistor 34 a
Since the potential at the connection point of a moves clockwise on the circumference shown in FIG. 4, the phase shift amount φ ′ of the entire phase shifter 200a continuously decreases accordingly. On the contrary, variable resistance 3
When the resistance value of 4a decreases, the potential at the connection point between the capacitor 32 and the variable resistor 34a moves counterclockwise on the circumference shown in FIG. 4, and accordingly, the phase shift amount φ of the entire phase shifter 200a. ′ Also grows continuously.

Further, the phase shifter 200b shown in FIG.
More specifically has a configuration in which the variable resistor 34a is replaced with the FET 34b, and variably controls the gate voltage to continuously change the channel resistance, thereby changing the phase shift amount of the entire phase shifter 200b. It is changing. Note that FIG.
Similar to the phase shifters 100a and 100b shown in FIG. 5, a variable resistance is formed by a transmission gate in which a p-channel FET and an n-channel FET are connected in parallel to obtain a stable ON resistance regardless of the voltage level of the input signal. You may do it.

FIG. 7 is a diagram showing the structure of a phase shifter in which the amount of phase shift can be continuously changed by using a variable capacitance diode. In FIG. Bowl 10
0c, a phase advance type phase shifter 200c is shown in FIG.

The phase shifter 100c shown in FIG.
It has a configuration in which the capacitor 14 of the phase shifter 100 shown in (4) is replaced with a variable capacitance diode 14a, and the capacitance is changed by changing the reverse bias voltage applied between the anode and the cathode of the variable capacitance diode 14a. By changing continuously, the amount of phase shift of the entire phase shifter 100c also changes continuously. That is, the variable capacitance diode 14a
When the electrostatic capacitance of the resistor decreases and the voltage VC1 across it increases, the potential at the connection point between the resistor 12 and the variable capacitance diode 14a moves counterclockwise on the circumference shown in FIG. Phase shift amount φ of the entire phase shifter 100c
Also becomes smaller continuously. On the contrary, variable capacitance diode 1
When the electrostatic capacitance of 4a increases and the voltage VC1 across it decreases, the potential at the connection point between the resistor 12 and the variable capacitance diode 14a moves clockwise on the circumference shown in FIG. Phase shift amount φ of the entire phase shifter 100c
Also grows continuously.

Similarly, the phase shifter 200c shown in FIG.
Has a configuration in which the capacitor 32 of the phase shifter 200 shown in FIG. 3 is replaced with a variable capacitance diode 32a,
By changing the reverse bias voltage applied between the anode and the cathode of the variable capacitance diode 32a and continuously changing the capacitance thereof, the phase shift amount of the entire phase shifter 200c also continuously changes. That is, when the capacitance of the variable capacitance diode 32a decreases and the voltage VC2 across it increases, the potential at the connection point between the resistor 34 and the variable capacitance diode 32a moves counterclockwise on the circumference shown in FIG. Therefore, the phase shift amount φ ′ of the entire phase shifter 200c continuously increases accordingly. On the contrary, the capacitance of the variable capacitance diode 32a increases and the voltage V
When C2 becomes small, the resistor 34 and the variable capacitance diode 32
Since the potential at the connection point of a moves clockwise on the circumference shown in FIG. 2, the phase shift amount φ ′ of the entire phase shifter 200c continuously decreases accordingly.

The variable capacitance diode 1 shown in FIG.
The capacitor connected in series with 4a or 32a is for blocking a direct current, and its impedance is extremely small at the operating frequency, that is, is set to a large capacitance so as not to affect the frequency characteristic.

Further, as shown in FIG. 5 to FIG. 7 mentioned above, the phase shift amount of the entire phase shifter is continuously changed by changing the element constant of either the resistor or the capacitor forming the series circuit. However, it is also possible to change the element constants of both the resistor and the capacitor that form the series circuit.

FIG. 8 is a diagram showing the structure of a phase shifter in which a series circuit is composed of a variable resistance and a variable capacitance diode. FIG. 1A shows the structure of a phase shifter 100d in which a series circuit is composed of a variable resistor 12a and a variable capacitance diode 14a. This phase shifter 100d continuously changes the phase shift amount φ by reducing the resistance value of the variable resistor 12a or by decreasing the electrostatic capacitance of the variable capacitance diode 14a and increasing the voltage VC1 across the variable capacitance diode 14a. Can be made smaller. On the contrary, in the phase shifter 100d, the phase shift amount φ is reduced by increasing the resistance value of the variable resistor 12a or by increasing the electrostatic capacitance of the variable capacitance diode 14a and decreasing the voltage VC1 across it. It can be continuously increased.

Further, FIG. 9B shows the structure of the phase shifter 200d in which the series circuit is composed of the variable capacitance diode 32a and the variable resistor 34a. This phase shifter 200
d is to continuously reduce the phase shift amount φ'by increasing the electrostatic capacitance of the variable capacitance diode 32a and decreasing the voltage VC2 across the variable capacitance diode 32a, or by increasing the resistance value of the variable resistor 34a. You can On the contrary, the phase shifter 200d includes the variable capacitance diode 32a.
The phase shift amount .phi. 'Can be continuously increased by decreasing the electrostatic capacitance and increasing the voltage VC2 across it or by decreasing the resistance value of the variable resistor 34a.

FIG. 9 is a diagram showing a modified example in which the capacitor 14 and the like used in the phase shifter 100 and the like shown in the above-mentioned first and second embodiments are constituted by a circuit instead of a single element. The entire circuit shown corresponds to the capacitor 14.

The capacitor 14b shown in the figure includes a capacitor 210 having a predetermined electrostatic capacitance C0, two operational amplifiers (operational amplifiers) 212 and 214, and four resistors 21.
6, 218, 220, 222.

In the operational amplifier 212 of the first stage, a resistor 218 (whose resistance value is R18) is connected between the output terminal and the inverting input terminal, and the inverting input terminal further has the resistor 216 (this resistance value). Is designated as R16).

Between the voltage E0 applied to the non-inverting input terminal of the first stage operational amplifier 212 and the voltage E1 appearing at the output terminal,

[Equation 16] There is a relationship. The first-stage operational amplifier 212 mainly functions as a buffer that performs impedance conversion, and the gain may be 1. The case of gain 1 is R
When 18 / R16 = 0, that is, R16 is infinite (resistor 21
6 should be removed), or R18 should be set to 0Ω (it should be directly connected).

The second-stage operational amplifier 214 has a resistor 222 (whose resistance value is R22) connected between the output terminal and the inverting input terminal, and the inverting input terminal and the output of the operational amplifier 212 described above. Resistor 22 between terminals
0 (this resistance value is R20) is connected, and the non-inverting input terminal is grounded.

When the voltage appearing at the output terminal of the second stage operational amplifier 214 is E2, the voltage E2 between this voltage E2 and the voltage E1 appearing at the output terminal of the first stage operational amplifier 212 is:

[Equation 17] There is a relationship. In this way, the second-stage operational amplifier 214 functions as an inverting amplifier, and the first-stage operational amplifier 2 is used to set the input side to high impedance.
Twelve are used.

Further, between the non-inverting input terminal of the first-stage operational amplifier 212 and the output terminal of the second-stage operational amplifier 214 thus connected, there is a predetermined capacitance as described above. The capacitor 210 is connected.

When the transfer function of the entire circuit excluding the capacitor 210 in the capacitor 14b shown in FIG. 9 is K, the capacitor 14b can be represented by the system diagram shown in FIG. FIG. 11 is a system diagram in which this is converted by the Miller's theorem.

When the impedance Z0 shown in FIG. 10 is used to represent the impedance Z1 shown in FIG.

(Equation 18) Becomes Here, in the case of the capacitor 14b shown in FIG. 9, the impedance Z0 = 1 / (jωC0),
Substituting this into equation (18),

[Formula 19]

(Equation 20) Becomes The equation (20) indicates that the capacitance C0 of the capacitor 210 in the capacitor 14b has apparently become (1-K) times.

Therefore, when the gain of the amplifier is negative, K is always larger than 1, so that the electrostatic capacitance C0 can be changed to a larger one.

By the way, the capacitor 14b shown in FIG.
The gain of the amplifier at the op amps 212 and 2
The gain K of the amplifier constituted by 14 as a whole is (1
From equations (6) and (17),

[Equation 21] Becomes Substituting equation (21) into equation (20),

[Equation 22] Becomes Therefore, the four resistors 216, 218, 22
By setting the resistance value of 0, 222 to a predetermined value,
The apparent capacitance C between the two terminals 224 and 226 can be increased.

When the gain of the amplifier by the first stage operational amplifier 212 is 1, that is, when R16 is infinite (resistor 216 is removed) or R18 is set to 0Ω as described above, R18 / R16 When = 0, the above equation (22) is simplified and

(Equation 23) Becomes

FIG. 12 is a diagram showing the structure of the capacitor 14c from which the resistor 216 connected to the inverting input terminal of the first operational amplifier 212 shown in FIG. 9 is removed. In this case, since the electrostatic capacitance C appearing between the terminals 224 and 226 is expressed by the equation (23), it is possible to change it from C0 to the larger one simply by changing the ratio of R22 and R20.

As described above, in the above-mentioned capacitor 14b or 14c, the resistance ratio R of the resistance 220 and the resistance 222 is R.
22 / R20 or resistance ratio R of the resistor 216 and the resistor 218
By changing 18 / R16, the capacitance C0 of the actually connected capacitor 210 can be apparently increased. Therefore, when the phase shifter 100 shown in FIG. 1 or the like is formed on a semiconductor substrate, a small capacitor 210 is formed on the semiconductor substrate and the circuit shown in FIG. 9 or 12 is formed. Can be converted into a large electrostatic capacitance C, which is convenient for integration. In particular, if a large capacitance can be secured in this way, the mounting area of the phase shifter 100 and the like can be reduced, and the material cost and the like can be reduced.

Further, the resistors 216, 218, 220, 22
At least one of the two (capacitor 1 shown in FIG.
In the case of 4c, at least one of the resistors 220 and 222) is formed by a variable resistor.
By forming a variable resistance by a -FET, J-FET, or a transmission gate in which a p-channel FET and an n-channel FET are connected in parallel, a capacitor having a variable capacitance can be easily formed. Therefore, by using this capacitor instead of the variable capacitance diode 14a shown in FIG.
It is possible to form a phase shifter capable of arbitrarily changing the amount of phase shift within a certain range.

Since the first stage operational amplifier 212 is used as a buffer for increasing the input impedance as described above, the operational amplifier 212 may be replaced with an emitter follower circuit or a source follower circuit.

FIG. 13 is a diagram showing the structure of the capacitor 14d using the emitter follower circuit in the first stage. The capacitor 14d shown in the same figure is an emitter follower circuit 22 including a first-stage operational amplifier 212 and two resistors 216 and 218 shown in FIG.
It has a configuration in which it is replaced with 8.

FIG. 14 is a diagram showing the structure of the capacitor 14e using the source follower circuit in the first stage. The capacitor 14e shown in the figure has a configuration in which the first-stage operational amplifier 212 and the two resistors 216 and 218 shown in FIG. 9 are replaced with a source follower circuit 230 including an FET and a resistor.

The capacitors 14d and 14e described above are also included.
Of each of the terminals 220 by changing the resistance ratio of the resistors 220 and 222 connected to the operational amplifier 214.
It is the same as the capacitor 14b and the like shown in FIG. 9 and the like in that the apparent electrostatic capacitance C between 4 and 226 can be arbitrarily changed. Therefore, at least one of the resistors 220 and 222 is connected to the MOS-FET, J-FET, or p-type.
By replacing the variable resistance formed by the transmission gate in which the channel FET and the n-channel FET are connected in parallel, a variable capacitance capacitor can be constructed, and this capacitor is shown in FIG. By using the variable capacitance diode 14a instead of the variable capacitance diode 14a, it is possible to form a phase shifter capable of arbitrarily changing the amount of phase shift within a certain range.

By the way, in the above-mentioned capacitor 14b and the like, the capacitance C0 of the capacitor 210 is actually changed to the larger one. However, as is clear from the equation (20), the gain of the amplifier is set between 0 and 1. If you can,
The apparent capacitance C can be changed to be smaller than C0.

FIG. 15 shows a capacitor 14f having an apparent capacitance smaller than that of an actual element.
It is a figure which shows the structure of. Capacitor 14f shown in FIG.
Is a capacitor 210 having a predetermined capacitance C0,
Two operational amplifiers 232 and 234 and two resistors 23
6, 238.

The operational amplifier 232 of the first stage has an output terminal connected to the inverting input terminal, is a non-inverting amplifier with a gain of 1, and mainly functions as a buffer for performing impedance conversion. Similarly, the output terminal of the second-stage operational amplifier 234 is also connected to the inverting input terminal, and functions as a non-inverting amplifier having a gain of 1. Further, a voltage dividing circuit by resistors 236 and 238 is inserted between these two non-inverting amplifiers.

By thus inserting the voltage dividing circuit, the overall gain including the two non-inverting amplifiers can be freely set between 0 and less than 1.

By the way, the capacitor 14 shown in FIG.
The gain of the amplifier at f, that is, the gain K of the amplifier constituted by the entire operational amplifiers 232 and 234 is equal to the resistance 2
36 and a resistor 238, which is determined by the voltage division ratio of the voltage dividing circuit, and the respective resistors are R36 and R38,

[Equation 24] Becomes Substituting this equation (24) into equation (20) and calculating the apparent capacitance C,

(Equation 25) Becomes

Therefore, by increasing the resistance ratio R38 / R36 of the resistors 236 and 238, the two terminals 2
The apparent capacitance C between 24 and 226 can be reduced.

In addition to the case where the voltage dividing ratio of the voltage dividing circuit by the resistors 236 and 238 is fixed, these two resistors 23
At least one of 6, 238 is a variable resistor (specifically,
Similar to the phase shifter 100b of the first embodiment, the MOS-FE is used.
This variable resistance can be formed by a T or J-FET, or a transmission gate in which a p-channel MOS and an n-channel MOS are connected in parallel). A variable capacitance capacitor can be easily formed. Therefore, by using this capacitor instead of the variable capacitance diode 14a shown in FIG. 7A, it is possible to form a phase shifter capable of arbitrarily changing the phase shift amount within a certain range.

The capacitor 14f shown in FIG.
Since the gain of the entire amplifier including the two operational amplifiers 232 and 234 is set to 1 or less, the whole may be replaced with an emitter follower circuit or a source follower circuit.

FIG. 16 is a diagram showing the configuration of a capacitor in which the entire amplifier including operational amplifiers 232 and 234 is replaced with an emitter follower circuit. The capacitor 14g shown in FIG. 7A includes a bipolar transistor 244 having two resistors 240 and 242 connected to the emitter, a voltage dividing point by the two resistors 240 and 242, and a transistor 244.
And a capacitor 210 connected to the base of the capacitor.

The gain of the above-mentioned emitter follower circuit is determined mainly according to the resistance ratio of the two resistors 240 and 242.
In addition, since the gain is always less than 1, the capacitance C0 actually possessed by the capacitor 210 can be apparently reduced, as can be seen from the equation (20). Moreover,
Since only one emitter follower circuit is used, the circuit configuration can be simplified and the maximum operating frequency can be set high.

FIG. 16B is a diagram showing a modification thereof, which is different in that the two resistors 240 and 242 in FIG. 16A are replaced with a variable resistor 246. By using the variable resistor 246 in this way, the gain can be changed arbitrarily and continuously, so that the apparent capacitance C can be changed arbitrarily and continuously, and the phase shifter 100 can be changed. The amount of phase shift such as can also be continuously changed.

The capacitor 1 shown in FIG.
4h replaces the two resistors 240 and 242 in FIG. 4A with one variable resistor 246, but at least one of the two resistors 240 and 242 may be configured by a variable resistor.

In FIG. 17, the capacitors 14g and 14h shown in FIGS. 16A and 16B are realized by a source follower circuit, and the bipolar transistor 244 is replaced with an FET 248.
FIG. 17A shows FIG. 16A and FIG. 17B shows FIG.
Each corresponds to (B).

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the gist of the present invention.

For example, the phase shifters of the above-described embodiments can theoretically shift the phase up to 180 ° by one, but when actually shifting the phase by 180 ° or more, it is 2 It suffices to connect and use more than one phase shifter.

Further, the operational amplifier 10 used in the phase shifter 100 of the first embodiment or the phase shifter 2 of the second embodiment.
The operational amplifier 30 used for 00 is an ideal one, and the resistors 16 and 18 or the resistors 36 and 38 are described as having the same resistance value. However, when actually designing a circuit, In order to correct the deviation, the resistor 18 or 38 which is a feedback resistor is replaced with the resistor 16 which is an input resistor.
Alternatively, set it larger than 18 to set the operational amplifiers 10 and 3
It is desirable to increase the gain of zero.

[0130]

As described above, according to the first aspect of the invention, a phase difference of about twice the phase angle shifted by the third resistor and the capacitor is generated between the input and output signals, which is large. The amount of phase shift can be set. Further, the amplitudes of the input signal and the output signal are equal, and the signal is not attenuated by performing the phase shift.

Further, according to the second aspect of the present invention, since the signal whose phase is delayed with respect to the input signal is input to the non-inverting input terminal of the operational amplifier, the delay having a phase shift amount twice this phase is provided. A phase type phase shifter can be easily realized.

Further, according to the invention of claim 3, since the signal whose phase is advanced with respect to the input signal is input to the non-inverting input terminal of the operational amplifier, the phase shift amount which is twice this phase is applied. A phase type phase shifter can be easily realized.

According to the fourth aspect of the present invention, the phase shift amount can be easily changed by changing the resistance value of the third resistor forming the series circuit. Similarly, according to the invention of claim 5, the phase shift amount can be easily changed by changing the electrostatic capacitance of the capacitor forming the series circuit.

According to the invention of claim 6, the phase shift amount can be easily changed by changing both the resistance value of the third resistor and the electrostatic capacitance of the capacitor forming the series circuit. be able to.

According to the invention of claim 7, the third resistance whose resistance value can be changed is specifically formed by the channel of the field effect transistor, and the third resistance can be easily changed by changing the gate voltage. The resistance value of the resistor 3 can be changed.

According to the invention of claim 8, the capacitance variable capacitor is specifically formed by a variable capacitance diode, and the capacitance can be easily changed only by changing the reverse bias voltage to be applied. You can

According to the ninth aspect of the invention, a capacitor is formed by connecting a capacitor element having a predetermined electrostatic capacity and an amplifier in parallel, and assuming that the transfer function of the amplifier is K, the amplifier The capacitance seen from the input side is (1-K) C0. Therefore, the apparent electrostatic capacitance can be made different from the actual electrostatic capacitance C0 according to the transfer function K, that is, the gain of the amplifier, and the small electrostatic capacitance can be made to appear apparently large. In particular, in the case where the entire phase shifter is integrated on the semiconductor substrate, only a small capacitor element can be formed on the semiconductor substrate. Therefore, if a small capacitance can be converted into a large capacitance, it is necessary for integration. It is particularly convenient, and there is also an effect of cost reduction by reducing the mounting area.

According to the tenth or eleventh aspect of the present invention, the gain of the amplifier when the electrostatic capacitance is changed is specifically shown. That is, since the apparent capacitance is (1-K) C0, the gain K of the amplifier is set to a negative value by setting the gain K of the amplifier to a negative value.
By setting it between 1 and 1, C0 can be changed to the smaller one.

According to the twelfth aspect of the invention, the amplifier according to the ninth or tenth aspect of the invention is specifically configured by an inverting amplifier using an operational amplifier, and the gain of the amplifier can always be negative. it can. According to the invention of claim 13, the input impedance can be increased by inserting a buffer on the input side of the operational amplifier. According to the invention of claim 14 or 15, the buffer is formed by using the operational amplifier or the emitter follower. It can be easily configured by a circuit or a source follower circuit.

According to the sixteenth aspect of the present invention, the amplification factor of the inverting amplifier can be varied by configuring the resistance constituting the inverting amplifier together with the above-mentioned operational amplifier with a variable resistor, which makes the appearance apparent. It is also possible to continuously change the electrostatic capacitance of and to continuously change the phase shift amount of the entire phase shifter.

According to the seventeenth or eighteenth aspect of the invention, the amplifier according to the ninth or eleventh aspect of the invention is specifically configured by two non-inverting amplifiers or an emitter follower circuit, a source follower circuit and a voltage dividing circuit. Therefore, by using the voltage dividing circuit, the overall gain can be set between 0 and 1 and the apparent capacitance can be changed to a value smaller than C0.

According to the nineteenth aspect of the present invention, the overall gain can be changed by forming the resistor composing the voltage dividing circuit by a variable resistor, whereby the apparent capacitance can be changed. Can also be continuously changed, and the phase shift amount of the entire phase shifter can be continuously changed.

According to the twentieth aspect of the invention, the capacitance of the capacitor included in the series circuit is changed and the resistance value of the third resistor is also changed. The phase shift amount can be easily changed by changing the constant. According to the invention of claim 21, the third resistance whose resistance value can be changed is specifically formed by the channel of the field effect transistor, and the resistance value of the third resistance can be easily changed only by changing the gate voltage. Can be changed.

According to the twenty-second aspect of the invention, the entire phase shifter is integrally formed on the semiconductor substrate, so that it is possible to reduce the size of the circuit and reduce the manufacturing cost by integration.

[0145]

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit configuration of a delay type phase shifter of a first embodiment.

FIG. 2 is a vector diagram showing the relationship between the input / output voltage of the phase shifter of this embodiment and the voltage appearing in a capacitor or the like.

FIG. 3 is a diagram showing a circuit configuration of a phase advance type phase shifter of a second embodiment.

FIG. 4 is a vector diagram showing the relationship between the input / output voltage of the phase shifter of this embodiment and the voltage appearing in a capacitor or the like.

FIG. 5 is a diagram showing a configuration of a lag type phase shifter in which the amount of phase shift can be continuously changed by using a variable resistor.

FIG. 6 is a diagram showing a configuration of a phase-advancing type phase shifter in which the amount of phase shift can be continuously changed by using a variable resistor.

FIG. 7 is a diagram showing a configuration of a phase shifter in which the amount of phase shift can be continuously changed by using a variable capacitance diode.

FIG. 8 is a diagram showing a configuration of a phase shifter in which the amount of phase shift can be continuously changed by using both a variable resistance and a variable capacitance diode.

FIG. 9 is a diagram showing a configuration of a capacitor in which an apparent capacitance is larger than that of an actual element.

FIG. 10 is a diagram showing the capacitor shown in FIG. 9 using a transfer function.

11 is a diagram in which the configuration shown in FIG. 10 is converted by the mirror theorem.

12 is a diagram showing a configuration of a capacitor in which a resistor connected to an inverting input terminal of the first operational amplifier shown in FIG. 9 is removed.

FIG. 13 is a diagram showing a configuration of a capacitor using an emitter follower circuit in the first stage.

FIG. 14 is a diagram showing a configuration of a capacitor using a source follower circuit in the first stage.

FIG. 15 is a diagram showing a configuration of a capacitor having an apparent capacitance smaller than that of an actual element.

16 is a diagram showing a configuration of a capacitor in which the entire amplifier including the two operational amplifiers included in FIG. 15 is replaced with an emitter follower circuit.

17 is a diagram showing a configuration in which the capacitor shown in FIG. 16 is realized by a source follower circuit.

FIG. 18 is a diagram showing a configuration of a conventional example.

[Explanation of symbols]

 10,30 Operational amplifier 12,16,18,34,36,38 Resistor 14,32 Capacitor 20 Input terminal 22 Output terminal 100,200 Phase shifter

Claims (22)

[Claims] 1. A first operational amplifier, wherein a first resistor is connected to the inverting input terminal, and an input signal is input to the inverting input terminal via the first resistor, and the first operational amplifier. And a third resistor and a capacitor connected between the inverting input terminal and the output terminal of the first resistor and the third resistor and the capacitor. The first signal is divided by dividing the voltage of the input signal applied to both ends. And a series circuit that is applied to the non-inverting input terminal of the operational amplifier. 2. The phase shifter according to claim 1, wherein the third resistor in the series circuit is connected to the first resistor, and the phase of the input signal is delayed by a predetermined angle before being output. . 3. The phase shifter according to claim 1, wherein the capacitor in the series circuit is connected to the first resistor and advances the phase of the input signal by a predetermined angle to output the phase-advanced signal. 4. The phase shifter according to claim 1, wherein the overall phase shift amount is changed by changing the resistance value of the third resistor. 5. The phase shifter according to claim 1, wherein an overall phase shift amount is changed by changing an electrostatic capacitance of the capacitor. 6. The transfer according to claim 1, wherein an overall phase shift amount is changed by changing a resistance value of the third resistor and an electrostatic capacitance of the capacitor. Phaser. 7. The total phase shift amount according to claim 4, wherein the third resistance is formed by a channel of a field effect transistor, and the gate resistance is changed to change the channel resistance. Characteristic phase shifter. 8. The capacitor according to claim 5, wherein the capacitor is formed of a variable capacitance diode,
A phase shifter characterized by changing the overall phase shift amount by changing the electrostatic capacitance by changing the reverse bias voltage applied between the anode and the cathode. 9. The amplifier according to claim 1, wherein the capacitor includes an amplifier having a predetermined gain and a capacitor element connected in parallel between the input and the output of the amplifier, and the capacitor from the input side of the amplifier. A phase shifter characterized in that the observed capacitance is different from the capacitance actually possessed by the capacitor element. 10. The capacitance according to claim 9, wherein the gain of the amplifier is set to a negative value so that the capacitance viewed from the input side of the amplifier is larger than the capacitance actually possessed by the capacitor element. Phase shifter characterized by. 11. The capacitance according to claim 9, wherein the gain of the amplifier is set between 0 and 1, so that the capacitance seen from the input side of the amplifier is smaller than the capacitance actually possessed by the capacitor element. A phase shifter characterized by: 12. The second operational amplifier according to claim 9, wherein the amplifier has a non-inverting input terminal connected to a fixed potential and an output terminal connected to one end of the capacitor element, and the capacitor element. A fourth resistor inserted between the other end of the second operational amplifier and the inverting input terminal of the second operational amplifier, and a fifth resistor inserted between the output terminal and the inverting input terminal of the second operational amplifier. A phase shifter comprising a resistor, and operating as an inverting amplifier having a negative gain. 13. The input impedance according to claim 12, wherein a buffer is further provided between the other end of the capacitor element and the fourth resistor in the preceding stage of the amplifier to increase the input impedance. Phaser. 14. The third operational amplifier according to claim 13, wherein the buffer has a non-inverting input terminal connected to the other end of the capacitor element and an output terminal connected to the fourth resistor. A sixth resistor connected between the output terminal and the inverting input terminal of the operational amplifier of No. 3, and a phase shifter. 15. The phase shifter according to claim 13, wherein the buffer comprises an emitter follower circuit or a source follower circuit. 16. The electrostatic capacitance of the capacitor according to claim 12, wherein at least one of the fourth, fifth, and sixth resistors is formed by a variable resistor, thereby changing the capacitance of the capacitor. A phase shifter characterized by changing the amount of phase shift. 17. The amplifier according to claim 9, further comprising: two non-inverting amplifiers arranged in series; and a first voltage dividing circuit connected between the two non-inverting amplifiers. , The overall gain is set between 0 and 1 according to the voltage dividing ratio of the first voltage dividing circuit. 18. The amplifier according to claim 9, wherein the amplifier is formed of an emitter follower circuit having a second voltage dividing circuit connected to the emitter side or a source follower circuit having a second voltage dividing circuit connected to the source side. By taking out the output from the second voltage dividing circuit, the overall gain is set between 0 and 1 according to the voltage dividing ratio of the second voltage dividing circuit. vessel. 19. The voltage dividing circuit according to claim 17, wherein the voltage dividing circuit includes a variable resistor,
A phase shifter characterized in that the capacitance of the capacitor is varied to change the total amount of phase shift. 20. The overall phase shift amount according to claim 16, wherein the resistance value of the third resistor included in the series circuit is changed and the capacitance of the capacitor is changed. A phase shifter characterized by: 21. The overall phase shift amount according to claim 20, wherein the third resistor is formed by a channel of a field effect transistor, and a gate voltage is changed to change a channel resistance, thereby changing an entire phase shift amount. Phase shifter. 22. The phase shifter according to claim 1, wherein the constituent parts are integrally formed on a semiconductor substrate.