JPS63115421A - Oscillation circuit - Google Patents

Abstract

PURPOSE:To surely stop oscillations synchronously with a control signal by adding an N channel MOS transistor which connected between two terminals of a resonance circuit and has gate input of a control signal for start/stop of oscillations to a position between a drain and a source. CONSTITUTION:A control signal is set at an H level in order to stop oscillations of an oscillation circuit. The output of a 2-input NOR gate 9 forming an amplifying circuit 1 is fixed at an L level. The electric charge stored in a capacitor 8 is discharged in a short time through an output transistor TR set at the L side of the gate 9. In this case, an n channel MOS TR10 connected to both ends of a resonance circuit 5 is turned on and therefore the electric charge stored in a capacitor 7 and an inductance 6 are also discharged in a short time through the TR10 and the output TR set at the L side of the gate 9. As a result, the oscillations of this circuit are surely stopped synchronously with the control signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oscillation circuit built into a digital IC or the like and used to obtain a reference signal or the like.

(Prior Art) FIG. 4 is a circuit diagram showing the principle of an oscillation circuit, where 1 is an amplifier circuit and 2 is a feedback circuit.

Further, FIG. 5 is a diagram showing an example of an oscillation circuit that is actually used, in which 1 is an amplifier circuit, 3 is an inverter, and 4 is a resistor. 5 is a resonant circuit, which corresponds to the feedback circuit 2 in FIG. Here, the resonant circuit 5 is, for example, as shown in this figure.
It is composed of an inductance of 6 and a capacitor of 7.8.

Furthermore, FIG. 6 is a diagram showing another example of the oscillation circuit, in which the inverter 3 in FIG. 5 is replaced with a two-manpower NOR gate 9.

In Fig. 4, the conditions for the circuit to oscillate are as follows: If the amplification factor of the amplifier circuit 1 is A, and the coefficient of the feedback circuit 2 is β, then IA・β1≧1 −・−・−−−−−(1 )L
(A-β)=2ni (n is an integer') - (2).

In Fig. 5, the frequency that most easily satisfies the above conditional expressions (11, (2)) is the carrier wave number.In other words, the frequency of equation (3) among the noise generated in the circuit by turning on the power, etc. The resonance circuit 5 and the amplifier circuit 1 selectively amplify only the noise that is present, resulting in oscillation.

Now, when the circuit in Figure 5 oscillates, the signal that causes the oscillation is noise, so the oscillation output at the start of oscillation is "
It is unclear whether the output will be from the L" level or the "H" level. Therefore, as shown in FIG. 6, the inverter 3 is operated by two people.

If a control signal is applied to one input instead of R9, this circuit will oscillate only when the control signal becomes "L", and the oscillation will always start from the "H" level. By doing this, the start of oscillation of this oscillation circuit can be synchronized with the control signal.

[Problem that the invention seeks to solve]

However, in the conventional oscillation circuit shown in FIG. 6, although it is possible to synchronize the start of oscillation, it is not possible to accurately synchronize when the oscillation is stopped. In other words, since the resonant circuit is composed of an inductance and a capacitor, the charge accumulated in these during oscillation is transferred to an amplifier circuit (in this case, two-man power N
Even if the output of the OR gate is fixed at the "H" level by a control signal and an attempt is made to discharge it, the charge in the capacitor at the input terminal of the amplifier circuit may not be discharged immediately, and oscillation may continue during that time. Also, when a control signal is input to start oscillation again, if the previous aftershock is still continuing, the output level at the start of oscillation will be affected by the aftershock,
There are problems in that it may become unclear whether the output is from "L" or "H".

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an oscillation circuit that can always reliably stop oscillation in synchronization with a control signal.

[Means for solving problems]

The oscillation circuit according to the present invention is provided with an N-channel MOS (MOS) run lister whose drain and source are connected between two terminals of a resonant circuit and whose gate is input with a control signal for starting and stopping oscillation.

[Effect]

The N-channel MO3I-run lister in this invention is:
When the oscillation is stopped, the control signal at the "H" level fixes the ONL, the resonant circuit, and both ends of the output at the "L" level at the same time, and the charges accumulated in the resonant circuit are discharged in a short time.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In the figure, 1 is an amplifier circuit, and 9 is this amplifier circuit 1.
is a two-man powered NOR gate, and 4 is a resistor. Further, 5 is a resonant circuit, 6 is an inductance constituting this resonant circuit 5, and 7.8 is a capacitor. Furthermore, 1
0 is an N-channel MO connected between two terminals of the resonant circuit 5
S) It is a run lister. A control signal input to one input terminal of the two-man power N0R9 is input to the gate of this MOS) run lister 10.

Next, the operation will be explained.

In order to stop the oscillation circuit, the control signal is set to “H”.
level. Then, the two-person power N that makes up the amplifier circuit 1
The output of OR gate 9 is fixed at "L" level. The charge accumulated in the capacitor 8 is 6 of these two people N0R9
It is discharged in a short time through the output transistor on the L'' side.At this time, the N-channel MOS (N-channel MOS) run resistor 10 connected to both ends of the resonant circuit 5 is turned on, so that the charge accumulated in the capacitor 7 and the inductance 6 is also discharged. It is discharged in a short time through this N-channel transistor 10 and the "L" side output transistor of the two-channel N0R9.In other words, the charge accumulated in the resonant circuit 5 is completely discharged as soon as the control signal becomes "H" level. It will be discharged in a short time.

At this time, if the sizes of the two-manufactured N0R9 and the N-channel MOS run lister 10 are made sufficiently large, all the charges will be discharged within the oscillation period, and the oscillation of this circuit will surely stop in synchronization with the control signal.

In the above embodiment, a circuit composed of a two-person N0R stage and a resistor was used for the amplifier circuit l, but this may also be a circuit as shown in FIG.
A resonant circuit 5 consisting of C6, C7, and C8 was used;
A resonant circuit using a crystal or ceramic oscillator 6a as shown in FIG. 3 may be used, and the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the oscillation circuit according to the present invention, the N-channel MO3I-run lister whose drain and source are connected between two terminals of the resonant circuit and whose gate input is a control signal for starting and stopping oscillation is provided. As a result, when the control signal is set to the "H" level, all accumulated charges in the resonant circuit can be discharged in a short time, and oscillation can be stopped reliably in synchronization with the control signal with a very simple circuit configuration. can.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an oscillation circuit according to an embodiment of the present invention;
2 and 3 are diagrams showing a part of an oscillation circuit according to another embodiment of the present invention, and FIG. 4 is a circuit diagram showing the principle of oscillation,
FIGS. 5 and 6 are diagrams showing conventional and commonly used oscillation circuits. 1 is an amplifier circuit, 2 is a feedback circuit, 3 is an inverter, 4 is a resistor, 5 is a resonant circuit, 6 is an inductance, 7.8 is a capacitor, 9 is a two-power NOR gate, 10 is an N-channel M
O3I-Run Lister. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In an oscillation circuit consisting of an amplification circuit having an amplification element that receives a control signal for starting and stopping oscillation as one input, and a resonant circuit connected to the amplification circuit, the resonance circuit between the drain and the source N-channel MO connected between two terminals of the circuit and using the above control signal as gate input
An oscillation circuit characterized by comprising an S transistor.