JPS5933921A - Phase shift circuit - Google Patents

Abstract

PURPOSE:To realize a phase shift circuit having good linearity and suitable for circuit integration, by using a triangle wave synchronizing with an input signal as an input signal to a comparator circuit. CONSTITUTION:The input signal A is inputted to a base of a transistor (TR) Q1. A terminal voltage at a capacitor C1 of an integrating circuit 2 is a triangle wave synchronizing with the input signal A. A multiplier 4 multiplies the input signal with a control voltage DELTAe of the multiplier 4. The level of the output of multiplication and that of the triangle wave are compared by a comparator 3. An output signal delayed to the input signal by 90 deg.+180 deg.XDELTAe/Vpp is obtained, where Vpp is a peak voltage of the triangle wave.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phase shift circuit, and particularly to a phase shift circuit suitable for integration.

A phase shift circuit that shifts the phase of a signal by a predetermined amount is generally constructed using passive elements, and if elements such as coils and capacitors are used, it is difficult to integrate the circuit. Furthermore, in order to control the amount of phase shift according to an external control signal, it is done by changing the impedance of the passive element.
This is often done by controlling the impedance of the transistor when it is on using an external control voltage. but,
This method has the disadvantage that the linearity of the phase shift characteristic is poor because the external control voltage and the impedance of the transistor do not change linearly.

In particular, when an FET (field effect element) is used as a transistor, it also has the disadvantage that it cannot be integrated by a so-called bipolar process.

Therefore, the present invention has been made to eliminate the above-mentioned conventional drawbacks, and its object is to provide a transfer-sum circuit that is easy to integrate and has good nearness.

The phase shift circuit according to the present invention generates a triangular wave synchronized with the input signal, and on the other hand, multiplies the rectangular wave synchronized with the input signal by an external control voltage, compares the levels of the five triangular waves and the multiplication output, and outputs this comparison output. It is characterized by having a phase-shifted output.

The present invention will be explained below based on the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention, in which an input signal hole is input to a differential amplifier 1 having a current mirror load and current is amplified. This differential amplifier 1 is a differential transistor Q
1. It consists of Q2, current source 1 and current mirror circuit. This current mirror circuit consists of transistors Qa, Q
a, and resistors Rt and R2, and a current amplified output is derived from a common collector contact point of transistors Q2 and Q4, and is applied to an integrating circuit 2 at the next stage.

In the integrating circuit 2, an integrating capacitor C1 is provided, and together with a current mirror load differential amplifier l, complete integration of the input signal is performed. The average level of the voltage at the terminals of capacitor C1 is determined by voltage source E and resistor R3, which are provided in parallel with capacitor C1. ) of the output of this integrating circuit 2 is the level comparator 3 in the next stage.
This is one input. This comparator consists of transistor Q
It is a current switching type differential circuit consisting of s+ Q6 and current source 2, and the collector output (2) from the resistor & of transistor Q5 becomes the output of the phase shift circuit.

On the other hand, the input signal (b) is supplied by one multiplier 4 having a double-balanced differential amplifier configuration, and an external control voltage is applied to each input to perform multiplication of the two inputs. The double-balanced differential amplifier has a first differential amplifier made up of transistors Q91QIO and resistors Rs and Ra, a second differential amplifier made up of transistors Q111Q12 and resistors R7+Rs, and two differential amplifiers. and a third differential amplifier that operates as a current source.

The third differential amplifier consists of transistors Q7+Qs and current source ■3, and the collector output of transistor Q7 becomes the current source of the first differential amplifier, and the collector output of transistor Q8 becomes the current source of the second differential amplifier. Serves as the amplifier's current source. An input signal (5) is applied as an input to the third differential amplifier, and an external control voltage is commonly supplied to the inputs of the first and second differential amplifiers. And these first
The output of the second differential amplifier and the second differential amplifier are also common, and the square multiplier output (C) is derived by the resistor R9 at the common collector point of the transistors Q9 and Qll, and becomes the individual input of the level comparator 3. ing. Note that the diode D1 is a level shift diode, and is used to set the average level of the multiplication output (0) equal to the average level E of the integral output (B) of the integrating circuit 2.

In such a circuit configuration, when a rectangular wave with a duty of 50% is applied to the input signal hole, the second
The operation of the circuit shown in FIG. 1 will be explained using the operation waveforms shown in FIGS. Note that (b) to (2) in FIGS. 2 to 4 correspond to the waveforms of signals (5) to (c) in FIG. 1, respectively.

First, referring to FIG. 2, the case is where the external control signal is zero. The terminal voltage of capacitor C1 becomes a triangular wave synchronized with the input signal hole as shown in Figure CB), and its average level is E.
It becomes. Since the control voltage in the multiplier 4 that is generated by one person is zero, the multiplication output is also zero, but at this time, the output point of the multiplier is set to the DC level E as shown in Figure (C). ing. Therefore, the output of the level comparator 3 is a 50% data signal having a 900 phase difference with the input signal hole as shown in FIG. 2.

Next, when the external control voltage becomes +Δe, the waveforms of each part become as shown in FIG. +Δ shown by the dotted line in figure (C)
Since the control voltage e is multiplied by the input signal shown by the dashed line, the multiplication output has an average level of E and a peak-to-peak level of 2. Δ.

(However, the input signal level is assumed to be l for simplicity.) This signal is in phase with the input signal. This is shown by the solid line in Figure (C), and this signal and the triangular wave are compared in level, but this comparison level (C) is changed by ±Δe with E as the reference in synchronization with the input signal. The comparison output is shown in figure (2)
). This indicates that there is a delay of 90 + 180 x Δe /Vp with respect to the input signal. This is ■.

is the peak-to-peak level of the triangular wave a3).

■pp=l10T. (2) is the current of the current source 11, C is the capacitance of the capacitor C1, and T is the period of the input signal.

When the external control voltage becomes -Δe, the waveforms of various parts are as shown in FIG. 4. Figure (When the control voltage -Δe indicated by the dotted line in Q is multiplied by the input signal indicated by the dashed-dotted line, the multiplication output has an average level of E, a peak-to-peak level of 2·Δe, and a peak-to-peak level equal to the input signal. The signal is in the opposite phase. Therefore, the comparison level of the comparator 3 is changed by ±Δe with respect to E in synchronization with the input signal, resulting in a comparison output as shown in (2). This is because the input signal This means that the phase is delayed by 90-18()XΔg/Vpp.

Therefore, it can be seen that the amount of phase shift is controlled in proportion to the change Δe in the external control voltage.

When the input signal is a sine wave, if the sine wave is amplified and applied to a level such that both the differential amplifier 1 and the double-balanced differential amplifier 4 are saturated and the sine wave is clipped, the above case can be solved. The same operation as a square wave having a 50% data rate is possible.

FIG. 5 is a circuit diagram of another embodiment of the present invention, in which parts equivalent to those in FIG. 1 are designated by the same reference numerals, and their explanation will be omitted. In this example, Is is connected to the resistor R12 by the current source 5.
Supply a current of = I3/2.

The purpose is to generate an average voltage E of a triangular wave.

The voltage of this resistor R12 is the voltage of the differential amplifier 501, and the output of the capacitor C1 is applied to its input. This differential amplifier 5 is a transistor Q! 5° Q16, current source 4, and transistor Q13. Q14 and resistance R
(+) and a current mirror consisting of RIO.The collector current of the transistor Q15 is taken out by this current mirror, smoothed by the capacitor C2 and the resistor Ru, and fed back to the input of the first stage amplifier 1.
It determines the average voltage E of the triangular wave and creates a stable circuit that is not affected by temperature drift or variations in resistance value. .

As described above, according to the present invention, since everything can be constructed from bipolar elements, integration is easy, and since the phase shift characteristic with respect to the external control voltage is linear, it has the advantage of excellent characteristics. The frequency of the input signal can be wideband by appropriately setting the integrating capacitor, and the phase shift range is 0 to 18.
It becomes wide at 0°.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Figs. 2 to 4 are operation waveform diagrams of each part explaining the circuit operation of Fig. 1, and Fig. 5 is a circuit diagram of another embodiment of the invention. be. Explanation of symbols of main parts 1...Differential amplifier 2...Integrator circuit 3...Level comparator 4...Multiplier Applicant Pioneer Corporation Agent Patent attorney Motohiko Fujimura

Claims (3)

[Claims] (1) Triangular wave generation means for generating a triangular wave synchronized with an input signal, multiplication means for multiplying a rectangular wave synchronized with the input signal by a phase shift control voltage, and a multiplication output of the triangular wave and the multiplication means. and a comparison means for comparing the levels;
A phase shift circuit characterized in that this comparison output is used as a phase shift output. (2) The phase shift circuit according to claim 1, wherein the triangular wave generating means has an integral circuit configuration. (3) The multiplication means has a double-balanced differential amplifier configuration that receives the input signal and the phase shift control voltage as inputs. Phase shift circuit.