JPH0332103A - Phase shift type rc oscillator - Google Patents

Abstract

PURPOSE:To facilitate the oscillation at a high frequency by providing an amplifier circuit to each RC integration circuit so as to lower the gain per circuit of the amplifier circuit. CONSTITUTION:An RC integration circuit comprising a resistor 1 and a capacitor 4 connects to a positive phase amplifier circuit comprising an amplifier circuit 9 and resistors 11, 12 to constitute a 1st stage delay type phase shifter to have a maximum phase shift of 90 deg.. Moreover, an RC integration circuit comprising a resistor 2 and a capacitor 5 connects to a positive phase amplifier circuit comprising an amplifier circuit 10 and resistors 13, 14 to constitute a next stage delay type phase shifter to have a maximum phase shift of 90 deg.. Thus, each gain of plural amplifier circuits is lowered and the oscillation at a high frequency is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to setting constants in internal elements of a phase-shifted RC oscillator for a desired oscillation frequency.

BACKGROUND OF THE INVENTION A conventional phase-shifting RC oscillator is shown in FIG. 2 as an example.
An RC integrating circuit in which three slow-phase phase shifters are connected in series is known.

The circuit in FIG. 2 is composed of a circuit block I and a suppressor block ■, where the circuit block ■ is a phase inversion amplifier circuit, and the circuit block ■ is an 18o.

This is a slow-phase phase shift circuit equipped with a phase shifter.

In Figure 2, 1, 2.3 are resistances, and the resistance value is R
1, R2, R3, 4, 5, and 6 are capacitors, the capacitance of which is C+*C2+, C3, 7 is a phase inversion amplifier circuit, and 8 is an output terminal.

FIG. 3 is a block diagram of the phase-shifted RC oscillator shown in FIG. In FIG. 3, numeral 19 is a phase inversion amplifier circuit, which is the same as circuit block I in FIG. 18 is an input terminal, and its potential is vI.

Further, 21 is an output terminal. The potential at the mutual connection point A is assumed to be ■. The conditions for the phase-shifting RC oscillator shown in FIG. 3 to oscillate are as follows: Condition (1) The phase inversion amplifier circuit 19 and phase shifter 20 in FIG. 3, that is, the circuit block I and circuit block ■ in FIG. The total gain must be 1 or more.

Condition (2) V+ and V are in phase.

It is.

FIG. 4 is a vector locus diagram of the transfer function obtained from circuit block I in FIG. Circuit block I in FIG. 2 is a phase inversion amplifier circuit, and in order to satisfy condition (2), the second
The circuit block (2) in the figure is a 180° phase shifter. The frequency at C in FIG. 4 becomes the oscillation frequency, and the greater value becomes the gain of the circuit block (2) in FIG.

Problem to be Solved by the Invention However, in the above configuration, since the phase-shifted RC oscillation device shown in FIG. 2 oscillates, in order to make the total gain of the oscillation device 1 or more, the circuit shown in FIG. The gain of block I must be increased. When the desired oscillation frequency is high, there is a problem that it is difficult to obtain the necessary gain.

Means for Solving the Problems According to the present invention, in a phase-shifting RC oscillator, a delayed phase shifter of an RC integrating circuit having a maximum phase shift of 90 degrees is connected via an amplifier circuit.

According to the present invention, since the phase-shifted RC oscillator has a plurality of amplifier circuits in its configuration, in order to achieve a total gain of 1 or more, it is necessary to increase The gain of each amplifier circuit can be lowered, and oscillation at a high frequency can be easily achieved.

Embodiment FIG. 1 is a circuit diagram of an embodiment of a phase-shifted RC oscillator according to the present invention. 9, 10 are amplifier circuits, 11, 1
2.13.14 is a resistance. Each of the circuit elements 1 to 8 is the same as each element of the conventional example shown in FIG. 2, and a description thereof will be omitted.

Next, the operation of the phase-shifted RC oscillator of this embodiment configured as described above will be explained. The RC integration circuit consists of a resistor 1 and a capacitor 4, an amplifier circuit 9 and a resistor 11.
．． The maximum phase shift amount is 90" by connecting with the positive phase amplifier circuit consisting of 12 to form the first stage slow phase shifter.
have.

In addition, the RC integrating circuit composed of the resistor 2 and the capacitor 5 is connected to the amplifier circuit 10 and the positive phase amplifier circuit composed of the resistors 13 and 14 to constitute the next stage slow phase shifter. It has a maximum phase shift ff of 190". Furthermore, the RC integration circuit consisting of the resistor 3 and capacitor 6 is connected to the phase inverting amplifier circuit 7 to form a slow phase shifter and has a maximum phase shift of 270". It is something.

The oscillation conditions of the phase-shifted RC oscillator shown in FIG. 1 are the same as the conditions (1) and C2) of the conventional example already described. That is, matching the phases of V] and V shown in condition (2) (in-phase) can make the phase delay 360° by using the two-stage slow phase shifter and the slow phase shifter. So I can be fully satisfied. Furthermore, in order to achieve a gain of 1 or more as shown in condition (1), it is practical to achieve a total gain of 1 or more by cascading two positive phase amplifier circuits and the phase inverting amplifier circuit 7, which is fully satisfactory. . These amplifier circuits are connected in cascade in three stages, so the gain can be shared, and the gain of each amplifier circuit can be divided into three stages.
It can be made lower than the conventional example shown in the figure.

As described above, according to this embodiment, by providing each RC integrating circuit with an amplifier circuit, the gain per amplifier circuit can be lowered.

Although this embodiment achieved this by using an operational amplifier as an amplifier circuit, other amplifier circuits may also be used.

As described in detail, according to the present invention, by providing an amplifier circuit in each RC integrating circuit, the gain per circuit of the amplifier circuit can be lowered, and the gain of the amplifier circuit can be increased. This makes it possible to realize an excellent phase-shifting RC oscillator that can easily oscillate at difficult high frequencies.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a phase-shifted RC oscillator according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a conventional phase-shifted RC oscillator, and FIG. 3 is a circuit diagram of a phase-shifted RC oscillator as shown in FIG. FIG. 4 is a block diagram of the device and a Peltle locus diagram obtained from the transfer function. 1.2.3...Resistance, 4,5.6...
Capacitor, 7... Phase inversion amplifier circuit, 8...
...Output terminal, 9.10...Amplification circuit, 1
1,12.13.14...Resistance, 15.16.
17... Buffer, 18... Input terminal, 19... Phase inversion amplifier circuit, 20...
・180° slow phase shifter, 21...Output terminal.

Claims (1)

[Claims] Two stages of slow phase shifters configured by coupling a high input impedance positive phase amplifier circuit to the output side of the first RC integrating circuit are connected in cascade, and a phase inverting amplifier circuit is connected to the second RC integrating circuit. further cascade-connecting phase inversion type slow phase shifters configured by combining the two stages, and feeding back the output of the phase inversion type slow phase shifter to the first stage input of the two stages of cascaded slow phase shifters. A phase-shifted RC oscillator with a configuration that allows