JPS6077502A - Oscillating circuit - Google Patents

Abstract

PURPOSE:To decrease the scale of the circuit and power consumption by providing a switching element between an input terminal of an active BPF and a terminal to which a reference voltage is given so as to attain oscillation and stop of oscillation. CONSTITUTION:The active BPF1 deciding the oscillating frequency consists of an amplifier 11 having an oscillating function and keeping the oscillation, an input terminal 2 to the amplifier 11, a terminal 3 to which a reference potential VE is given, and an output terminal 4 feeding back an output to the input of the amplifier 11. The switching element 12 is provided between the terminals 2 and 3 and the element 12 is on/off-controlled so as to start and stop the oscillation.

Description

[Detailed description of the invention] When an oscillator circuit, especially a sine wave oscillator circuit in communication equipment that sends a sine wave as a signal to a general subscriber telephone line, etc., the output path in the oscillation state ζ2 is separated by a mechanical contact such as a relay. It was controlled by this. However, in this case, since it is in a constant oscillation state, current is constantly flowing, and therefore power is constantly consumed. In addition, in some cases, by using a relay, a circuit to eliminate noise that occurs when the 0N10FF is applied, and a correction circuit to fix the output impedance due to changes in the C2 output impedance when the 0N10FF changes, etc., are required, which reduces power consumption and circuits. The drawback was that it was large in size.

In addition, in recent years there has been an increasing demand for smaller size and lower power consumption in communication equipment, and with this, oscillation circuits also need to be smaller and have lower power consumption.Furthermore, the time required for 0N10FF oscillation has also increased compared to the time detected by the receiving side. The purpose of this is to provide a sine wave oscillation circuit that can reduce the circuit size and power consumption by performing 0N10FF control of the oscillation circuit using electrical switching elements such as transistors. In a sine wave oscillation circuit consisting of an amplifier that amplifies the output and inputs it to the active bandpass filter at a feedback rate of +1 or more, the point with the highest signal level, that is, the output potential of the amplifier, and a certain standard (Secondly, to control oscillation/stopping by changing the feedback rate between the input and output of the active bandpass filter to +1 or more or +1 or less. Fig. 1 is a circuit configuration diagram showing an embodiment of the present invention.In Fig. 1, 1 is an active pass filter (hereinafter abbreviated as BPF); input terminal 2, 3.1 output terminal 4, operational amplifier 5.3
It consists of two resistors 6,8.10 and two capacitors 7.9. The non-inverting input terminal 3a of the operational amplifier 5 is 1) I
The output terminal 4a is directly connected to the input terminal 3 described in I, and the output terminal 4a is directly connected to the output terminal 41Z. On the other hand, the inverting input terminal 2a
One end of the resistor 6 and one end of the capacitor 1 are connected to
The other end of the resistor 6 is connected to the output terminal 4a. Furthermore, a resistor 8, a capacitor 9, and a resistor 10 are connected to the other end of the capacitor 7, and the other ends of each are connected to the input terminal 2.
, output terminal 4a.

It is connected to input terminal 3 (3a).

Reference numeral 11 denotes an inverting amplifier, the input and output of which are directly connected to the output terminal 4 and the input terminal 2, respectively, and one lead wire serving as a reference potential is connected to the input terminal 3. 12 is an NPN type transistor, whose base, emitter, and collector are connected to the control input terminal 13 and the input terminal 3, respectively.
, is connected to input terminal 2.

The sine wave oscillation circuit configured in this manner operates as follows.

Output of oscillation frequency determined by BPF 1 Vout
is input to the inverting amplifier 11 from the output terminal 4, and after being amplified, the BPF 1 is output as a positive feedback signal v0 having a constant value.
The input terminals 2) are added.

In this case, in order to maintain the oscillation state, the inverting amplifier 1
1 functions to output a positive feedback signal V0 from the BPF 1 to keep the α feedback rate above +1.

[i.e., a signal under such conditions]. While this is occurring, a constant oscillation frequency Vout is output from the output terminal 4. In this state, when a pulse-like control signal VO is applied from the control input terminal 13 to the pace of the transistor 12, the output signal of the inverting amplifier 11 becomes ■.

1E becomes the same potential as the reference potential vB, that is, it becomes a short circuit state, and as a result, the feedback ratio from BPF 1 becomes 1-1 or less and oscillation stops. Therefore, by using transistors, it is possible to reduce the circuit scale, power consumption, and power consumption.

fc, the value of each element constituting BPF 1 is determined in advance based on the above dispute (feedback rate is +1 or more or +1 or less)
It is set to satisfy.

Next, FIG. 2 shows one part of the inverting amplifier 11 in FIG.
This shows an active inverting amplifier.
Portions corresponding to those in FIG. 1 are given the same reference numerals. In FIG. 2, 21 is an operational amplifier, 22 is a capacitor for noise removal, 23.24 is a resistor that determines the amplification factor, 25 is a resistor for limiting the output current of the operational amplifier 21, and 26.27
)18PF 1 Kara (7)! lff1 return rate + 1
Above: Zener diode for limiter to keep it constant, Vout is amplifier input, vE is reference potential, v
o is the amplifier output. In this case, a resistor 25 is inserted so that the output current does not increase even if the transistor 12 shown in FIG. 1 is turned on. Furthermore, by adjusting the output current limiting resistor 25 and the noise eliminating capacitor 22, the rise of one oscillation can be controlled. Since the 0N10FF control of the oscillation circuit can be performed without using an impedance conversion circuit, it is possible to reduce the overall rz circuit scale and the amount of power consumed.

Furthermore, since it is an oscillation circuit using only a capacitor, a resistor, and a semiconductor element, the oscillation circuit can control oscillation from the outside, and can be fully adapted to the future implementation of r, cLsI, etc.

[Brief explanation of the drawing]

2F 1 is a circuit diagram showing an embodiment of the present invention;
FIG. 2 shows an example of a circuit diagram of the main part (inverting amplifier) of FIG. 1. 1 ...... Active band pass filter (BPF) 2.3 ...... Input terminal 4 ...... Output terminal 5・・・・・・
......Operation amplifier fi, 8.10...
Resistor 7.9 ...... Capacitor 11 ...
......Inverting amplifier 12...
・Transistor 13...... Control input terminal 21...... Operational amplifier 22...
...... Capacitor 23.24.25...
・Resistance 26.27 ... Zener diode Vout
......Output of the oscillation circuit (input of the inverting amplifier 11)

Claims (1)

[Scope of Claims] An amplifier having an oscillation function and sustaining oscillation, an input terminal for inputting the output of the amplifier, a terminal for providing a reference potential, and an output terminal for feeding back the output to the input of the amplifier; In the oscillation circuit composed of an active bandpass filter that determines the
An oscillation circuit characterized in that the oscillation circuit is configured to oscillate and stop the oscillation circuit.