JPS62115910A - Variable phase shifting circuit - Google Patents

Abstract

PURPOSE:To stabilize an output by providing the 2nd differential amplifier, a circuit which synthesizes the 1st-4th signals and obtains a phase variable output signal and a control means which controls together all current sources of the 1st-4th differential amplifiers in common in the same manner and changes the phase of a phase variable output signal. CONSTITUTION:In a variable phase shifting circuit adding vectors through the use of four-phase input signals with phase differences of 90 deg., a common phase shifting control signal controls the current sources S1-S4 of the differential amplifiers D1-D4 so that all four-phase input signals can be amplitude- controlled by the control signal. With Vc (control voltage) = Vr (reference voltage) given, all currents of a current source 22 are set so that they can flow in a transistor Q21. The current division ratio of the current of a current source 21 is changed by varying the control voltage Vc, which means that the variable current sources S1-S4 are simultaneously controlled. Thus a variable phase shifting circuit can be obtained which easily sets the variable range for shifting a phase to 180 deg. and can obtained a stable output without a critical change in the amplitude of said output corresponding to the control.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a variable phase shift circuit that can change the phase shift color of a signal in accordance with a control signal.

ETechnical Background of the Invention] As a conventional variable phase shift circuit, for example, there is a circuit as shown in FIG. This circuit uses 4-phase input signals A (0°) and B (180'>, C90°) with a phase difference of 90 degrees each.
, D (270°) are used. Input signals C and D are input to a first differential amplifier D consisting of transistors Q1 and Q2.
1 differential input, and the input signals A and B are supplied to the second and third differential amplifiers D2 and D consisting of transistors 03 to Q6.
3 differential inputs. From the first differential amplifier D1, a signal is taken out from the derivation part of the negative phase output of the input signal B, and from the second differential amplifier D2, the signal is taken out from the derivation part of the negative phase output of the input signal B. , a signal is taken out from the third differential amplifier D3 from a derivation section of the opposite phase output of the input signal Δ.

The respective outputs of the first to third differential amplifiers Dl to D3 are combined at the illustrated output point 0 to form a phase variable output signal. The differential amplifier 04 made up of transistors Q7 and Q8 is for controlling the currents of the second and third differential amplifiers D2 and D3 to control the phase of the variable phase output signal. Also Sl, 82
is a constant current source, Vc is a control voltage, and Vr is a reference voltage.

Vs is a power supply voltage, and R1-R4 are resistors.

The operation of the above circuit is as follows. The first differential amplifier D1 outputs a component of a voltage vector a, which is an amplified 90° component, at the illustrated output point 0, and the second differential amplifier D2 outputs a component of a voltage vector a which is an amplified 90° component.
The third differential amplifier D3 outputs a voltage vector pb which is an amplified 0° component at the indicated output 0 point, and the third differential amplifier D3 outputs the indicated output 0.
Voltage flat (1-p) with amplified 180° component at the point
) (-b) is output. Here, the fourth differential amplifier D4 including transistors Q7 and Q8 divides the current ID into P:(1-P) according to the control voltage.

(0≦P≦1) At the indicated output point 0, the above outputs are added, and Va=a +
pb+ (1-11) (-b)-a + (2P
-1) b. Since 0≦P≦1, phase shift control of Va from a-b to a+b is possible, and la I -1-al = tb l -1-bl
Then, a variable range of 90° is obtained.

FIG. 5(A) shows the range of vector change in the output due to phase shift control. On the other hand, if la l-1-al<lb 1=l-bl, a variable range of 90 degrees or more can be obtained. This situation is shown in FIG. 5(B).

[Problems with the background art] According to the above phase shift circuit, 1al-1-al-1bl-1
-bl under the condition of 90 as shown in Figure 5(A).
Only a variable range of ° can be obtained. So la l -1-
If at < lb l = t-bl, then Figure 5 (B
), the variable range 814 is 90 degrees or more, but the change in output amplitude becomes very large due to control. In order to make the phase shift variable range close to 180°, la l
<<1b l, and it was difficult to obtain a variable range of 180°.

[Object of the invention] This invention was made in view of the above circumstances, and it is possible to easily change the variable range of the phase shift to 180 degrees, and also to stabilize the output amplitude without large changes according to the control. The purpose is to provide a variable phase shift circuit that can obtain an output.

[Summary of the Invention] As shown in FIG. 1, the present invention provides a variable phase shift circuit that performs vector addition using four-phase input signals having a phase difference of 90 degrees, in which all of the four-phase input signals are control signals. The current sources of the differential amplifiers D1 to D4 are controlled by a common phase shift control signal so that the amplitude of the differential amplifiers D1 to D4 is controlled by a common phase shift control signal.

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

FIG. 1 shows an embodiment of the present invention, in which first to fourth signals A to D are supplied to input terminals 11 to 14, respectively. The first signal B is supplied to the bases of transistors Q11, Q14, and the second signal B is supplied to the bases of transistors Q12 and Q12.
, is supplied to the base of Q13. Further, a third signal C is supplied to the bases of transistors Q15 and Q18. A fourth signal is also supplied to the bases of transistors Q16 and Q17. Transistors Q11 and Q12 constitute a first differential amplifier D1, and transistors Q13 and Q1
4 constitutes a second differential amplifier D2, transistors Q15 and Q16 constitute a third differential amplifier D3, and transistors Q17 and Q18 constitute a fourth differential amplifier D.
4. and the first to fourth differential amplifiers D
Current sources S1 to S4 are connected to L to D4, respectively. The current sources S1 to S4 are commonly subjected to current control by a control voltage VC. However, the current sources S1 and S2 are in a differential relationship, and the relationship of their divided output currents is IP-1/21xiO and (1-IP-1□'2I) as shown in the figure.
The relationship is XiO. Further, the current sources S3 and S4 are also in a linear relationship, and the relationship between their branched output currents is a relationship of P×10 and (1-p)XiO, as shown in the figure.

The collectors of transistors Q11, Q13, Q15, and Q17 are connected to the power supply via resistor R11, and the collectors of transistors Q12, Q14, QlG, and Q18 are connected to resistor R1.
It is connected to the power source of voltage V[3 via 2 and used as an output section.

One embodiment of the present invention is constructed as described above, and the control wJ voltage VC is varied, so that the current of the current source, that is, the P(0
≦P≦1), it is possible to obtain phase variation as shown in FIG. Now the 90° phase shift component is vector a
Then, if the 0° phase shift component is expressed as a vector b, the signal Va at the output section A is va= (1-I P-1/2 l )
xa + I P-1/21x (-a) + Pb
+ (1-P) X (-b)= (1-2I P-
It can be expressed as 1/21) a+ (2P-1) b. From the variable range of 0≦P≦1, the phase shift control of Va from - to b via a is performed by 1q. Figure 2 (2A) - (2
F) shows how the phase of the output changes due to changes in P. Here, if 1al=lbl, the amplitude change of the output signal having a variable range of 180° is small as shown in the same figure (2F>).

FIG. 3 further specifically shows the present invention, particularly showing the first to fourth current sources 81 to 84 in detail. The same parts as in FIG. 1 will be described with the same reference numerals. Control voltage VC is applied to the base of transistor Q24. This transistor Q24 is paired with a transistor Q25 to form a differential amplifier D5, and both collectors are connected to a constant current m21 via resistors R18 and R19, respectively.
It is connected to the bias power supply VB via. 1-A reference voltage Vr is applied to the base of the transistor Q25. Transistors Q19, Q20, and Q21 are transistors that control the currents of the first and second differential amplifiers [)1 and [)2. Transistors Q19, Q20, Q21
are connected to the constant current source 22 via resistors R13, R14, and R15, respectively, and transistors Q19 and
The base of Q20 is connected to the bias power supply vb via resistors R22 and R21, respectively.

Further, the collectors of transistors Q19 and Q20 are connected to the emitters of transistors Q11 and Q12 of differential amplifier D1. Further, the base of the transistor Q21 is connected to the bias power supply vb via the resistor R20, and the collector is connected to the emitters of the transistors Q13 and Q14. Further, transistors Q22 and Q23 are transistors that control the currents of the differential amplifiers [)3 and [)4. The emitters of transistors Q22 and Q23 are connected to constant current source 23 via resistors R1G and R17, respectively, and the bases of transistors Q22 and Q23 are connected to bias power supply vb via resistors R22 and R21, respectively. Further, the collector of transistor Q22 is connected to the emitters of transistors Q15 and QlG, and the collector of transistor Q23 is connected to the emitters of transistors Q17 and Q10.

In the above configuration, control! If the l voltage Vc is varied,
The amount of potential drop occurring in resistors R21 and R22 is adjusted, and transistors Q20. The base bias of Q23, Q19, and Q22 can be varied. On the other hand, the base potential of transistor Q21 is fixed to the maximum potential that the bases of transistors Q19 and Q20 can have. Here, for example, Vc (
It is set so that all the current 22 for current flows through the transistor Q2+ when the control voltage (a voltage)=Vr (reference voltage). When VC is larger than vr and all the current of current source 21 flows through transistor Q24 (corresponding to 1), transistors Q20, Q21, and Q23 are turned on, and each has a current of 1/2 x 1O11/2 x io, io is flowing. Furthermore, when Vc is equal to Vr and half of the current from current source 21 flows through transistors Q24 and Q25 (P=
(equivalent to 1/2), transistors Q21, Q22, Q23
is turned on, and the current is 10.1 /2 X1O11 in each
/2xiO flows. In this way, by changing the control voltage VC and changing the current division ratio of the current source 21 (corresponding to changing P from 0 to 1), the variable current sources S1 to S4 in FIG. I will have to control it.

[Effects of the Invention] As explained above, the present invention has a variable range of phase shift of 18
It is possible to provide a variable phase shift circuit that can easily adjust the phase shift to 0° and that can obtain a stable output without a large change in the output layer width depending on the control.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a solid diagram showing the operation of the circuit in FIG. 1.
Fig. 3 is a circuit diagram showing a specific example of the circuit shown in Fig. 1, Fig. 4 is a circuit diagram showing a conventional phase shift circuit, and Fig. 5 is a vector diagram showing the operation of the circuit shown in Fig. 4. It is a diagram. Q11-Q25...transistor, 81-S4...
Current source, R11 to R19...resistance. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] a first differential amplifier in which first and second signals having a phase difference of 180 degrees serve as differential inputs and obtain a first output signal from a deriving section of an output having an antiphase relationship with the second signal; 1st
, a second differential amplifier which receives a second signal as a differential input and obtains a second output signal from a derivation section whose output is in an antiphase relationship with the first signal; 1
, third and fourth signals having a phase difference of 90 degrees from the second signal are differential inputs, and a third output signal is obtained from an output derivation unit having an opposite phase relationship with the third signal. a second differential amplifier in which the third and fourth signals serve as differential inputs and a fourth output signal is obtained from a derivation section of an output having an antiphase relationship with the fourth signal; , a circuit for synthesizing the first to fourth signals to obtain a phase variable output signal;
A variable phase shift circuit comprising: control means for controlling all the current sources of the fourth differential amplifier in the same way in common to vary the phase of the phase variable output signal.