JPS6282808A - Phase shifting circuit - Google Patents

Abstract

PURPOSE:To obtain a phase shifting circuit capable of easily changing a phase shifting value appropriate to the formation of an integrated circuit by adopting circuit constitution using the emitter diffusion capacity of a transistor (TR) as a capacitor element. CONSTITUTION:Generally, the emitter diffusion capacity existing in the TR is proportional to an emitter current IE. When potential VC is boosted or dripped, an emitter current IE is increased or reduced and an emitter current CE2 is reduced or increase. In accordance with said change, the emitter diffusion capacity CED1 of a TR 7 is increased or reduced and the emitter diffusion capacity CDE2 is reduced or increased, so that the phase shift of the 1st signal is increased or reduced and that of the 2nd signal is reduced or increased. The phase shift can be continuously changed 0-90 deg. or 90-0 deg. by selecting the potential VR of a reference signal input terminal 14 and the resistance values of the 1st and 2nd resistors 11, 12 properly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a phase shift circuit, and particularly to a phase shift circuit suitable for integration into an integrated circuit.

[Conventional technology]

Phase shift circuits applicable to conventional integrated circuits are often constructed of elements such as inductance, capacitance, and resistance having fixed constants.

Figure 2 is a circuit diagram showing an example of a conventional phase shift circuit. This circuit connects two inductances with fixed constants in series, and uses both ends as an input terminal and an output terminal. It has a T-shaped circuit configuration in which a fixed constant capacitor is connected between the connection point and the reference potential end. Therefore, if the signal frequency is constant, the phase difference between the input signal and the output signal (hereinafter referred to as phase shift amount) is fixed to a constant value depending on the constant of the element used.

[Problem that the invention seeks to solve]

In the conventional phase shift circuit described above, the amount of phase shift when the frequency is constant is fixed by the constant of the element used, so there is a problem that it is difficult to make the amount of phase shift variable. there were.

An object of the present invention is to provide a phase shift circuit that can easily change the amount of phase shift and is suitable for integration into an integrated circuit.

[Means for solving problems]

The phase shift circuit of the present invention includes first and second transistors whose collectors are both connected to a power supply terminal, and whose collectors are connected to the first transistor.
a third transistor whose pace is connected to the emitter of the transistor and whose pace is connected to a control signal input terminal for controlling the emitter currents of the first and second transistors; and whose collector is connected to the emitter of the second transistor and whose emitter is a fourth transistor connected to the emitter of the third transistor and whose base is connected to the reference signal input terminal; the emitters of the third and fourth transistors are connected to the constant current source; The other end is connected to the input end of the second signal, and the other end is connected to the base of the first and second transistors, respectively, and the output end of the first and second signal is connected to the first and second signal input ends of the first and second transistors. It has first and second resistors forming a CR circuit together with an emitter diffusion capacitor.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

This embodiment consists of first and second transistors 7.8., whose collectors are connected to the power supply terminal 6. ! :, the collector is connected to the emitter of the first transistor 7 and the base is the emitter current of the first and second transistors 7.8 El*I
The first transistor 9 is connected to the control signal input terminal 13 that controls E2, the collector is connected to the emitter of the second transistor 8, the emitter is connected to the emitter of the third transistor 9, and the pace is the reference signal input terminal! 4, one end is connected to the emitters of the third and fourth transistors 9, 100, and the other end is connected to the reference potential terminal 3.
a constant current source 15 connected to the first and second signal input terminals 1.4 at one end and connected to the first and second signal input terminals 1.4, respectively, and the other end connected to the paces of the first and second transistors 7.8, respectively; and the emitter diffusion capacitance CDE1* of the first and second transistors 7.8 connected to the output terminals 2 and 5 of the second signal.
It is configured to include first and second resistors 11 and 12 that form a CR circuit with COH2.

Next, the operation of this circuit will be explained.

In general, the emitter diffusion capacitance CD present in a transistor
I can be expressed by the following formula.

q: Electron charge 1.602xlO"(C') k: Porzmey constant 1.384 X l o-2" (Jlo
K) T: Absolute temperature [0K] W: Base width [m] D: Diffusion constant (m”/8) IE: Emitter current (A) As shown in equation (1), emitter diffusion capacitance CDI is equal to emitter current I There is a proportional relationship with .In this example,
This emitter current I is the third current Is of the constant current source 15.
and the emitter current "El + shunted to the first and second transistors 7.8 by the fourth transistors 9 and 10.
This diversion amount can be changed differentially by changing the potential vc of the control signal input terminal 13 with respect to the potential vR of the reference signal input terminal 14. Therefore, when the potential ■c is raised (or lowered), the emitter current IEI
increases (or decreases), the emitter current E2 decreases (or increases), and along with this, the emitter diffusion capacitance CD! of the first transistor 7! ! 1 increases (or decreases) and the emitter diffusion capacitance CDE2 of the second transistor 8 decreases (or increases), so that the potential vR of the phase shift amount terminal 14 of the signal gt and the resistance of the first and second resistors By choosing the value appropriately, the amount of phase shift can be changed from around 00 to around 90' (or 90').
It can be changed continuously (from around 00° to around 00).

〔Effect of the invention〕

As explained above, the present invention has a circuit configuration that uses the emitter diffusion capacitance of a transistor as a capacitance element, so that the amount of phase shift can be easily changed.
Moreover, there is an effect that a phase shift circuit suitable for integration can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing an example of a conventional phase shift circuit. 1... Input end of the first signal, 2... Output end of the first signal, 3... Reference potential end, 4...
...Second signal input terminal, 5...Second signal output terminal, 6...Power supply terminal, 7, 8, 9.1
0...Transistor, 11.12...
Resistor, 13... Control signal input terminal, 14...
...Reference signal input terminal, 15... Constant current source, 16
．． 17...Inductance, 18...
capacitor. Figure 82 depicts agent patent attorney Shinro Uchihara.

Claims (1)

[Claims] first and second transistors whose collectors are both connected to a power supply terminal; whose collectors are connected to the emitter of the first transistor and whose bases are connected to a control signal input terminal that controls emitter currents of the first and second transistors; a fourth transistor whose collector is connected to the emitter of the second transistor, whose emitter is connected to the emitter of the third transistor, and whose base is connected to the reference signal input terminal; and a constant current source connected to the emitter of the fourth transistor, one end connected to the input terminals of the first and second signals, and the other end connected to the bases of the first and second transistors, respectively. A phase shift circuit comprising first and second resistors connected to the output terminals of the first and second signals and forming a CR circuit with the emitter diffusion capacitances of the first and second transistors. .