JP2015091084A - Four phase output voltage controlled oscillator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain low phase noise characteristics even when the oscillation frequency of a differential signal in a differential voltage controlled oscillator is varied.SOLUTION: A four phase output voltage controlled oscillator comprises: a variable phase shifter 4 having pass characteristics being phase characteristics having a delay of 90 degrees at a resonant frequency fcoincident with the oscillation frequency of a differential VCO1 and delaying the phase of a differential signal by 90 degrees to output a differential signal between 90 degrees and 270 degrees being a differential signal after the phase delay to a differential VCO5; and a variable phase shifter 8 having pass characteristics being phase characteristics having a delay of 90 degrees at a resonant frequency fcoincident with the oscillation frequency of the differential VCO5 and delaying the phase of a differential signal by 90 degrees to output a differential signal between 180 degrees and 0 (360) degrees being a differential signal after the phase delay to the differential VCO1.

Description

  The present invention relates to a four-phase output voltage controlled oscillator that outputs signals having phases of 0 degrees, 90 degrees, 180 degrees, and 270 degrees.

As one of the components that influence the quality of wireless communication, there is a high demand for a voltage controlled oscillator with low phase noise.
For example, a four-phase output voltage controlled oscillator is a voltage controlled oscillator that outputs signals having phases of 0 degrees, 90 degrees, 180 degrees, and 270 degrees.
In the conventional four-phase output voltage controlled oscillator, in order to reduce the phase noise, a phase shifter is provided between the two differential voltage controlled oscillators so that the phases of the oscillation wave and the injection wave are the same. (For example, see Non-Patent Documents 1 and 2).

FIG. 7 is a block diagram showing a four-phase output voltage controlled oscillator disclosed in Non-Patent Documents 1 and 2 below.
The 4-phase output voltage controlled oscillator shown in FIG. 7 includes differential voltage controlled oscillators 101 and 103 and fixed 90 degree phase shifters 102 and 104.
The differential voltage controlled oscillator 101 outputs the 0 degree and 180 degree differential signals to the fixed 90 degree phase shifter 102 in synchronization with the 0 degree and 180 degree differential signals.
The fixed 90-degree phase shifter 102 delays the phases of the 0-degree and 180-degree differential signals output from the differential voltage-controlled oscillator 101 by 90 degrees, and differential-voltage controls the 90-degree and 270-degree differential signals. Output to the oscillator 103.
The differential voltage controlled oscillator 103 synchronizes the 90 and 270 degree differential signals output from the fixed 90 degree phase shifter 102 with the 90 and 270 degree differential signals. Output to.
The fixed 90-degree phase shifter 104 delays the phase of the 90-degree and 270-degree differential signals output from the differential voltage controlled oscillator 103 by 90 degrees, and compares the differential signals of 180 degrees and 0 (360) degrees. Output to the dynamic voltage controlled oscillator 101.

P. Andreani “Analysis and Design of a 1.8-GHz CMOS LC Quadrature VCO” IEEE Journal of Solid-State Circuits, December 2002, p. 1737〜1747 A. Mirzaei “The Quadrature LC Oscillator: A Complete Portrait Based on Injection Locking” IEEE Journal of Solid-State Circuits, September 2007, p. 1916-1932

  Since the conventional four-phase output voltage controlled oscillator is configured as described above, the phase shift amount of the fixed 90 degree phase shifters 102 and 104 is set to 90 degrees. Since 104 generally has frequency characteristics, if the oscillation frequency of the differential signal in the differential voltage controlled oscillators 101 and 103 changes, the phase shift amount of the fixed 90 degree phase shifters 102 and 104 starts from 90 degrees. There is a problem that the phase noise characteristic is deteriorated due to the deviation.

  The present invention has been made to solve the above-described problems. A four-phase output voltage controlled oscillator capable of obtaining low phase noise characteristics even when the oscillation frequency of a differential signal in the differential voltage controlled oscillator changes. The purpose is to obtain.

  The four-phase output voltage controlled oscillator according to the present invention oscillates a second differential signal having the same phase as the first differential signal in synchronization with the first differential signal having a phase difference of 180 degrees. The first differential voltage controlled oscillator has a pass characteristic that is a phase characteristic delayed by 90 degrees at a frequency that matches the oscillation frequency of the second differential signal in the first differential voltage controlled oscillator. A first variable phase shifter that delays the phase of the second differential signal oscillated by the differential voltage controlled oscillator of 90 degrees and outputs a third differential signal that is a differential signal after the phase delay; In synchronism with the third differential signal output from the first variable phase shifter, the third differential signal has an oscillation frequency that matches the oscillation frequency of the second differential signal in the first differential voltage controlled oscillator. A second differential voltage controlled oscillator that oscillates a fourth differential signal having the same phase as that of the second differential signal, and a second differential voltage The fourth differential signal generated by the second differential voltage controlled oscillator has a passing characteristic that is a phase characteristic delayed by 90 degrees at a frequency that matches the oscillation frequency of the fourth differential signal in the controlled oscillator. A second variable phase shifter that delays the phase of the signal by 90 degrees and outputs the first differential signal, which is a differential signal after the phase delay, to the first differential voltage controlled oscillator; It is.

  According to the present invention, the first differential voltage controlled oscillator has a pass characteristic having a phase characteristic delayed by 90 degrees at a frequency that matches the oscillation frequency of the second differential signal. The first differential signal oscillated by the voltage controlled oscillator is delayed by 90 degrees, and the third differential signal, which is the differential signal after the phase delay, is output to the second differential voltage controlled oscillator. And a pass characteristic that is a phase characteristic delayed by 90 degrees at a frequency that matches the oscillation frequency of the fourth differential signal in the second differential voltage controlled oscillator. The fourth differential signal oscillated by the dynamic voltage controlled oscillator is delayed by 90 degrees, and the first differential signal, which is the differential signal after the phase delay, is output to the first differential voltage controlled oscillator. 2 variable phase shifters, so that the first and second differential voltage control Also vary the oscillation frequency of the differential signal in oscillator, the effect of low phase noise characteristics.

1 is a schematic configuration diagram showing a four-phase output voltage controlled oscillator according to a first embodiment of the present invention. It is a block diagram which shows the detail of the 4-phase output voltage control oscillator by Embodiment 1 of this invention. It is explanatory drawing which shows the passage characteristic of four variable resonators. It is a block diagram which shows the detail of the 4-phase output voltage control oscillator by Embodiment 2 of this invention. It is a schematic block diagram which shows the 4-phase output voltage control oscillator by Embodiment 3 of this invention. It is a block diagram which shows the detail of the 4-phase output voltage control oscillator by Embodiment 3 of this invention. It is a block diagram which shows the 4-phase output voltage control oscillator currently disclosed by the nonpatent literatures 1 and 2. FIG.

Embodiment 1 FIG.
FIG. 1 is a schematic configuration diagram showing a four-phase output voltage controlled oscillator according to the first embodiment of the present invention, and FIG. 2 is a configuration diagram showing details of the four-phase output voltage controlled oscillator according to the first embodiment of the present invention. .
1 and 2, a differential VCO (Voltage Controlled Oscillator) 1 is a differential signal of 0 degrees and 180 degrees output from the variable phase shifter 8 (a first differential signal having a phase difference of 180 degrees). Is a first differential voltage controlled oscillator that oscillates a differential signal of 0 degrees and 180 degrees (a second differential signal having the same phase as the first differential signal) in synchronization with.

The differential VCO 1 includes a variable resonator 2 (first variable resonator) and an active circuit 3, and the variable resonator 2 is a parallel resonance circuit including an inductor L ₀ and a capacitor C ₀ , and the resonance frequency is It becomes the oscillation frequency of the differential signal in the differential VCO1.
The active circuit 3 includes oscillation device transistors M ₁ and M ₂ and injection differential pair transistors M ₃ and M _4, and oscillates differential signals of 0 ° and 180 ° at the resonance frequency of the variable resonator 2. Circuit.
As the differential VCO 1, for example, a voltage-controlled oscillator such as a cross-coupled oscillator, a differential Colpitts oscillator, or a push-push oscillator can be considered.

The variable phase shifter 4 has a passing characteristic that has a phase characteristic delayed by 90 degrees at a resonance frequency that matches the oscillation frequency of the differential signal in the differential VCO 1, and the phase of the differential signal oscillated by the differential VCO 1. Is a first variable phase shifter that outputs a differential signal (third differential signal) of 90 degrees and 270 degrees that is a differential signal after phase delay to the differential VCO 5.
That is, the variable phase shifter 4 is composed of a variable resonator (second variable resonator) having the same frequency characteristics as the variable resonator 2, and this variable resonator is composed of an inductor L _ps and a capacitor C _ps. This is a parallel resonant circuit.
The variable resonator which is the variable phase shifter 4 delays the phase of the differential signal oscillated by the differential VCO 1 by 90 degrees, and differentially differentials the 90 and 270 degree differential signals after the phase delay. Output to VCO5.

The differential VCO 5 is an oscillation frequency that matches the oscillation frequency of the differential signal in the differential VCO 1 in synchronization with the 90 ° and 270 ° differential signals output from the variable phase shifter 4 and is 90 ° and 270 °. A second differential voltage controlled oscillator that oscillates a differential signal (a fourth differential signal having the same phase as the third differential signal).
Differential VCO5 is composed of a variable resonator 6 (third variable resonator) and the active circuit 7, the variable resonator 6 is a parallel resonance circuit consisting of an inductor L ₀ and capacitor C _0, its resonant frequency This is the oscillation frequency of the differential signal in the differential VCO 5.
The active circuit 7 is composed of oscillation device transistors M ₅ and M ₆ and injection differential pair transistors M ₇ and M _8, and oscillates differential signals of 90 ° and 270 ° at the resonance frequency of the variable resonator 6. Circuit.
As the differential VCO 5, for example, a voltage-controlled oscillator such as a cross-coupled oscillator, a differential Colpitts oscillator, or a push-push oscillator can be considered.

The variable phase shifter 8 has a pass characteristic that has a phase characteristic delayed by 90 degrees at a resonance frequency that matches the oscillation frequency of the differential signal in the differential VCO 5, and the phase of the differential signal oscillated by the differential VCO 5. Is a second variable phase shifter that outputs a differential signal (first differential signal) of 180 degrees and 0 (360) degrees, which is a differential signal after phase delay, by 90 degrees, to the differential VCO1. is there.
That is, the variable phase shifter 8 is composed of a variable resonator (fourth variable resonator) having the same frequency characteristic as that of the variable resonator 6, and this variable resonator includes an inductor L _ps and a capacitor C _ps. This is a parallel resonant circuit.
The variable resonator which is the variable phase shifter 8 delays the phase of the differential signal oscillated by the differential VCO 5 by 90 degrees, and the differential signals of 0 degrees and 0 (360) degrees which are the differential signals after the phase delay. Is output to the differential VCO1.

The output terminal 11 is a terminal that outputs a high-frequency signal having a phase of 0 degrees.
The output terminal 12 is a terminal that outputs a high-frequency signal having a phase of 180 degrees.
The output terminal 13 is a terminal that outputs a high-frequency signal having a phase of 90 degrees.
The output terminal 14 is a terminal that outputs a high-frequency signal having a phase of 270 degrees.

The buffer amplifier 21 is connected between the differential VCO 1 and the variable phase shifter 4 and allows the differential signal output from the differential VCO 1 to flow in the direction of the variable phase shifter 4, but the variable phase shifter 4. This is an element that prevents the flow from the direction of the differential VCO1 to the differential VCO1.
The buffer amplifier 22 is connected between the differential VCO 5 and the variable phase shifter 8 and allows a differential signal output from the differential VCO 5 to flow in the direction of the variable phase shifter 8, but the variable phase shifter 8. This is an element that prevents the flow from the direction of the differential VCO 5 to the differential VCO 5.
The capacitors 23 and 24 are capacitors for the bias circuit, and are provided so that direct current is not applied to the injection differential pair transistors M ₇ and M ₈ .
Capacitors 25 and 26 are capacitors for the bias circuit, and are provided so that direct current is not applied to the injection differential pair transistors M ₃ and M ₄ .

Next, the operation will be described.
In the first embodiment, four variable resonators (a variable resonator 2 in the differential VCO 1, a variable resonator that is the variable phase shifter 4, a variable resonator 6 in the differential VCO 5, and a variable phase shifter 8). The values of the inductors L ₀ and L _ps and the capacitors C _ps and L _ps are set in advance so that a certain variable resonator has the same frequency characteristics.
The power supply voltages of the differential VCOs 1 and 5 and the variable phase shifters 4 and 8 are common to V _dd , and the voltage for controlling the resonance frequency of the four variable resonators is common to V _cont .
Accordingly, the resonance frequencies f ₀ of the four variable resonators are always the same frequency. Even if the resonance frequency f ₀ of the variable resonator 2 in the differential VCO ₁ changes, the resonance of the remaining three variable resonators The frequency f ₀ changes similarly.
Figure 3 is an explanatory view showing the pass characteristics of four of the variable resonator, the four pass characteristics of the variable resonator, abrupt phase change is obtained in the vicinity of the resonance frequency f _0, the resonance frequency f ₀ at 90 ° It has a delayed phase characteristic.

When the differential VCO 1 receives a differential signal of 0 degrees and 180 degrees from the variable phase shifter 8, the active circuit 3 in the differential VCO 1 has 0 degrees and 180 degrees at the resonance frequency f ₀ of the variable resonator 2. The differential signal is oscillated.
Variable phase shifter 4 is a variable resonator of the resonance frequency f _0, and has a pass characteristic which is a phase characteristic of 90-degree lag at the resonant frequency f _0.
Therefore, when the variable phase shifter 4 receives the differential signals of 0 degrees and 180 degrees from the differential VCO 1, the phase of the differential signal is delayed by 90 degrees, and the differential signal after the phase delay is 90 degrees. And 270 degree differential signals are output to the differential VCO 5.
The resonance frequency f ₀ of the variable resonator is variable phase shifter 4 is always the same as the resonance frequency f ₀ of the variable resonator 2. For this reason, even if the resonance frequency f ₀ of the variable resonator 2 changes and the oscillation frequency of the differential signal in the differential VCO 1 changes, the resonance frequency f ₀ of the variable resonator that is the variable phase shifter 4 changes. Similarly, the phase of the differential signal can be accurately delayed by 90 degrees.

When the differential VCO 5 receives the differential signals of 90 degrees and 270 degrees from the variable phase shifter 4, the active circuit 7 in the differential VCO 5 has 90 degrees and 270 degrees at the resonance frequency f ₀ of the variable resonator 6. The differential signal is oscillated.
Variable phase shifter 8 is a variable resonator of the resonance frequency f _0, and has a pass characteristic at the resonance frequency f ₀ is the topological characteristics of the 90-degree delay.
For this reason, when the variable phase shifter 8 receives the differential signals of 90 degrees and 270 degrees from the differential VCO 5, the phase of the differential signal is delayed by 90 degrees, and the differential signal after the phase delay is 180 degrees. And 0 (360) degree differential signals are output to the differential VCO1.
The resonance frequency f ₀ of the variable resonator is variable phase shifter 8 is always the same as the resonance frequency f ₀ of the variable resonator 6. Therefore, even if the resonance frequency f ₀ of the variable resonator 6 changes and the oscillation frequency of the differential signal in the differential VCO 5 changes, the resonance frequency f ₀ of the variable resonator that is the variable phase shifter 8 changes. Similarly, the phase of the differential signal can be accurately delayed by 90 degrees.

As is apparent from the above, according to the first embodiment, the phase characteristic has a phase characteristic delayed by 90 degrees at the resonance frequency f ₀ that coincides with the oscillation frequency of the differential signal in the differential VCO 1. A variable phase shifter 4 that delays the phase of the differential signal oscillated by the differential VCO 1 by 90 degrees, and outputs the differential signals of 90 degrees and 270 degrees that are the delayed phase signals to the differential VCO 5; The differential VCO 5 has a pass characteristic that is a phase characteristic delayed by 90 degrees at the resonance frequency f ₀ that matches the oscillation frequency of the differential signal, and delays the phase of the differential signal oscillated by the differential VCO 5 by 90 degrees. Since the differential phase-shifted differential signal of 180 degrees and 0 (360) degrees is output to the differential VCO 1, the variable phase shifter 8 is provided. The oscillation frequency of the differential signal changes In addition, there is an effect that low phase noise characteristics can be obtained in a wide band.

Embodiment 2. FIG.
FIG. 4 is a block diagram showing details of the four-phase output voltage controlled oscillator according to the second embodiment of the present invention. In FIG. 4, the same reference numerals as those in FIG.
Capacitors 31 and 32 are capacitors for adjusting the resonance characteristics of the variable resonator 2 in the differential VCO 1, and are connected between the differential VCO 1 and the buffer amplifier 21.
Capacitors 33 and 34 are capacitors for adjusting the resonance characteristics of the variable resonator 6 in the differential VCO 5, and are connected between the differential VCO 5 and the buffer amplifier 22.
In the second embodiment, the capacitors 31 and 32 constitute the first capacitor, the capacitors 23 and 24 constitute the second capacitor, the capacitors 33 and 34 constitute the third capacitor, and the capacitors 25 and 26. Constitutes a fourth capacity.
In addition, the capacity | capacitances 31-34 and the capacity | capacitances 23-26 are set to the same capacity | capacitance value.

Next, the operation will be described.
In the first embodiment, the four variable resonators (the variable resonator 2 in the differential VCO 1, the variable resonator that is the variable phase shifter 4, the variable resonator 6 in the differential VCO 5, and the variable phase shifter 8). In order to make a certain variable resonator) have the same frequency characteristics, the values of the inductors L ₀ and L _ps and the capacitors C _ps and L _ps are set in advance. The resonance characteristics of the resonator are affected by the parasitic capacitances of the injection differential pair transistors M ₃ , M ₄ , M ₇ , M ₈ , the buffer amplifiers 21 and 22, and the capacitors 23 to 26 for the bias circuit. In the second embodiment, the same transistors are used as the injection differential pair transistors M ₃ , M ₄ , M ₇ , and M ₈ , and capacitors 31 to 34 for adjusting resonance characteristics are added.

That is, in the first embodiment, the bias circuit capacitors 23 to 26 are provided so that direct current is not applied to the injection differential pair transistors M ₃ , M ₄ , M ₇ , and M ₈ . Since the resonance frequencies f ₀ of the variable resonators that are the variable phase shifters 4 and 8 are slightly changed by providing the capacitors 23 to 26, the capacitors 31 to 34 for adjusting the resonance characteristics are added in the second embodiment. Thus, the resonance frequency f ₀ of the variable resonators 2 and 6 is adjusted so that the resonance characteristics of the four variable resonators are accurately matched.
As a result, according to the second embodiment, there is an effect that a lower phase noise characteristic can be obtained than in the first embodiment.

Embodiment 3 FIG.
FIG. 5 is a schematic configuration diagram showing a four-phase output voltage controlled oscillator according to the third embodiment of the present invention, and FIG. 6 is a configuration diagram showing details of the four-phase output voltage controlled oscillator according to the third embodiment of the present invention. .
5 and FIG. 6, the same reference numerals as those in FIG. 1 and FIG.
The variable phase shifter 41 has a passing characteristic that is a phase characteristic delayed by 90 degrees at a frequency that matches the oscillation frequency of the differential signal in the differential VCO 1, and the phase of the differential signal oscillated by the differential VCO 1 is changed. This is a first variable phase shifter that delays 90 degrees and outputs differential signals (third differential signal) of 90 degrees and 270 degrees that are differential signals after phase delay to the differential VCO 5.
That is, the variable phase shifter 41 includes an RC filter (first RC filter) including a resistor R _ps and a capacitor C _ps whose phase shift amount changes in accordance with a change in the resonance frequency of the variable resonator 2. The RC filter delays the phase of the differential signal oscillated by the differential VCO 1 by 90 degrees, and outputs the differential signals of 90 degrees and 270 degrees after the phase delay to the differential VCO 5.

The variable phase shifter 42 has a passing characteristic that is a phase characteristic delayed by 90 degrees at a frequency that matches the oscillation frequency of the differential signal in the differential VCO 5, and the phase of the differential signal oscillated by the differential VCO 5 is changed. A second variable phase shifter that outputs a differential signal (first differential signal) of 180 degrees and 0 (360) degrees, which is a differential signal after phase delay, by 90 degrees, to the differential VCO1. .
That is, the variable phase shifter 42 includes an RC filter (second RC filter) including a resistor R _ps and a capacitor C _ps whose phase shift amount changes in accordance with a change in the resonance frequency of the variable resonator 6. The RC filter delays the phase of the differential signal oscillated by the differential VCO 5 by 90 degrees, and outputs the differential signals of 180 degrees and 0 (360) degrees after the phase delay to the differential VCO 1. To do.

In the example of FIG. 6, the capacitors 31 to 34 are not provided, but the capacitors 31 to 34 are provided in the four-phase output voltage controlled oscillator of FIG. 6 as well as the four-phase output voltage controlled oscillator of FIG. 4. May be.
In the third embodiment, the variable resonator 2 in the differential VCO 1 forms a first variable resonator, and the variable resonator 6 in the differential VCO 5 forms a second variable resonator. In the first and second embodiments, the variable resonator 6 in the differential VCO 5 is described as the third variable resonator.

Next, the operation will be described.
In the third embodiment, the voltage for controlling the resonance frequency of the variable resonator 2 in the differential VCO 1 and the variable resonator 6 in the differential VCO 5 is common to V _cont1 .
The voltage for controlling the phase shift amount of the RC filter that is the variable phase shifter 4 and the RC filter that is the variable phase shifter 8 is the same as V _cont2 .
At this time, the inductors L ₀ , capacitors C _ps , C _ps and resistor R are preliminarily set so that all the RC filters which are the variable resonators 2 and 6 and the variable phase shifters 4 and 8 have the same frequency characteristics. _{The ps} value is set, and the control voltages V _cont1 and V _cont2 are set.
That is, the phase of the differential signal output from the variable phase shifter 41 matches the phase of the differential signal oscillated by the differential VCO 1, and the phase of the differential signal output from the variable phase shifter 42 is Control voltages V _cont1 and V _cont2 are set so as to match the phase of the differential signal oscillated by the differential VCO 5.
Therefore, even if the resonance frequency f ₀ of the variable resonators 2 and 6 in the differential VCOs 1 and 5 changes and the phase of the differential signal oscillated by the differential VCOs 1 and 5 changes, the variable phase shift Similarly, the phase of the differential signal output from the devices 41 and 42 also changes.

When the differential VCO 1 receives a differential signal of 0 degrees and 180 degrees from the variable phase shifter 8, the active circuit 3 in the differential VCO 1 has 0 degrees and 180 degrees at the resonance frequency f ₀ of the variable resonator 2. The differential signal is oscillated.
When the variable phase shifter 41 receives the differential signals of 0 degrees and 180 degrees from the differential VCO 1, the phase of the differential signal is delayed by 90 degrees, and the differential signals after the phase delay are 90 degrees and 270 degrees. Are output to the differential VCO 5.
Note that, as described above, the variable phase shifter 41 is configured by an RC filter whose amount of phase shift changes in accordance with the change in the resonance frequency f ₀ of the variable resonator 2. Even if the resonance frequency f ₀ changes and the phase of the differential signal oscillated by the differential VCO 1 changes, the phase of the differential signal output from the variable phase shifter 41 changes similarly. Therefore, even if the phase of the differential signal oscillated by the differential VCO 1 changes, the phase of the differential signal can be accurately delayed by 90 degrees.

When the differential VCO 5 receives the differential signals of 90 degrees and 270 degrees from the variable phase shifter 4, the active circuit 7 in the differential VCO 5 has 90 degrees and 270 degrees at the resonance frequency f ₀ of the variable resonator 6. The differential signal is oscillated.
When the variable phase shifter 42 receives the differential signals of 90 degrees and 270 degrees from the differential VCO 5, the phase of the differential signal is delayed by 90 degrees, and the differential signal after the phase delay is 180 degrees and 0 ( 360) degree differential signal is output to the differential VCO1.
Note that, as described above, the variable phase shifter 42 is composed of an RC filter whose amount of phase shift changes in accordance with the change in the resonance frequency f ₀ of the variable resonator 6. Even if the resonance frequency f ₀ changes and the phase of the differential signal oscillated by the differential VCO 5 changes, the phase of the differential signal output from the variable phase shifter 42 also changes. Therefore, even if the phase of the differential signal oscillated by the differential VCO 5 changes, the phase of the differential signal can be accurately delayed by 90 degrees.

As is apparent from the above, according to the third embodiment, the variable phase shifters 41 and 42 are separated from the RC filter in which the phase shift amount changes in accordance with the change in the resonance frequency f ₀ of the variable resonators 2 and 6. Thus, as in the first and second embodiments, even if the oscillation frequency of the differential signal in the differential VCOs 1 and 5 changes, there is an effect that low phase noise characteristics can be obtained in a wide band.

  In the present invention, within the scope of the invention, any combination of the embodiments, or any modification of any component in each embodiment, or omission of any component in each embodiment is possible. .

  DESCRIPTION OF SYMBOLS 1 Differential VCO (1st differential voltage control oscillator), 2 Variable resonator (1st variable resonator), 3 Active circuit, 4 Variable phase shifter (1st variable phase shifter, 2nd variable) Resonator), 5 differential VCO (second differential voltage controlled oscillator), 6 variable resonator (third variable resonator, second variable resonator), 7 active circuit, 8 variable phase shifter (first) 2 variable phase shifter, 4th variable resonator), 11-14 output terminals, 21, 22 buffer amplifiers, 23, 24 capacitors (second capacitors), 25, 26 capacitors (fourth capacitors), 31 , 32 capacity (first capacity), 33, 34 capacity (third capacity), 41 variable phase shifter (first variable phase shifter, first RC filter), 42 variable phase shifter (second Variable phase shifter, second RC filter), 101, 103 differential voltage controlled oscillator, 102, 104 fixed 90 degree phase shifter.

Claims (4)

A first differential voltage controlled oscillator for oscillating a second differential signal having the same phase as the first differential signal in synchronization with a first differential signal having a phase difference of 180 degrees;
The first differential voltage controlled oscillator has a pass characteristic that is a phase characteristic delayed by 90 degrees at a frequency that matches the oscillation frequency of the second differential signal in the first differential voltage controlled oscillator. A first variable phase shifter that delays the phase of the oscillated second differential signal by 90 degrees and outputs a third differential signal that is a differential signal after the phase delay;
In synchronization with the third differential signal output from the first variable phase shifter, the oscillation frequency coincides with the oscillation frequency of the second differential signal in the first differential voltage controlled oscillator, and A second differential voltage controlled oscillator that oscillates a fourth differential signal having the same phase as the third differential signal;
The second differential voltage controlled oscillator has a passing characteristic that is a phase characteristic delayed by 90 degrees at a frequency that matches the oscillation frequency of the fourth differential signal in the second differential voltage controlled oscillator. A second variable for delaying the phase of the oscillated fourth differential signal by 90 degrees and outputting the first differential signal, which is a differential signal after the phase delay, to the first differential voltage controlled oscillator A four-phase output voltage controlled oscillator comprising a phase shifter. The first differential voltage controlled oscillator includes a first variable resonator, and a resonance frequency of the first variable resonator becomes an oscillation frequency of a second differential signal in the first differential voltage controlled oscillator. ,
The first variable phase shifter includes a second variable resonator having the same frequency characteristic as the first variable resonator, and the second variable resonator is the first differential resonator. The phase of the second differential signal oscillated by the voltage controlled oscillator is delayed by 90 degrees, and a third differential signal that is a differential signal after the phase delay is output,
The second differential voltage controlled oscillator includes a third variable resonator, and a resonance frequency of the third variable resonator is an oscillation frequency of a fourth differential signal in the second differential voltage controlled oscillator. ,
The second variable phase shifter includes a fourth variable resonator having the same frequency characteristics as the third variable resonator, and the fourth variable resonator is the second differential resonator. The phase of the fourth differential signal oscillated by the voltage controlled oscillator is delayed by 90 degrees, and the first differential signal that is the differential signal after the phase delay is output to the first differential voltage controlled oscillator. The four-phase output voltage controlled oscillator according to claim 1, wherein: The first differential voltage controlled oscillator includes a first variable resonator, and a resonance frequency of the first variable resonator becomes an oscillation frequency of a second differential signal in the first differential voltage controlled oscillator. ,
The first variable phase shifter includes a first RC filter whose amount of phase shift changes in accordance with a change in the resonance frequency of the first variable resonator, and the first RC filter is the first RC filter. Delaying the phase of the second differential signal oscillated by the first differential voltage controlled oscillator by 90 degrees, and outputting a third differential signal that is a differential signal after the phase delay,
The second differential voltage controlled oscillator includes a second variable resonator, and a resonance frequency of the second variable resonator is an oscillation frequency of a fourth differential signal in the second differential voltage controlled oscillator. ,
The second variable phase shifter includes a second RC filter whose amount of phase shift changes in accordance with a change in the resonance frequency of the second variable resonator, and the second RC filter includes the second RC filter. The phase of the fourth differential signal oscillated by the second differential voltage controlled oscillator is delayed by 90 degrees, and the first differential signal which is the differential signal after the phase delay is changed to the first differential voltage. 2. The four-phase output voltage controlled oscillator according to claim 1, wherein the four-phase output voltage controlled oscillator is output to a controlled oscillator. A first capacitor connected between the first differential voltage controlled oscillator and the first variable phase shifter;
A second capacitor connected between the first variable phase shifter and the second differential voltage controlled oscillator;
A third capacitor connected between the second differential voltage controlled oscillator and the second variable phase shifter;
A fourth capacitor connected between the second variable phase shifter and the first differential voltage controlled oscillator;
4. The four-phase output voltage controlled oscillator according to claim 1, wherein the first to fourth capacitors are set to the same capacitance value. 5.

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