JPS62109406A - Oscillation circuit - Google Patents

Abstract

PURPOSE:To ensure the easy supply of a stable oscillation frequency even in case the power supply voltage has a low level and the frequency has a high level, by switching an internal amplifier between the 3-stage and 1-stage constitutions of the inverter gate by means of a switch. CONSTITUTION:A the time of start of oscillation a switch 6 is connected to the A side to form an oscillation circuit containing an amplifier having the 3-stage structure of an inverter gate with high gain. Then the amplitude level of the oscillation frequency is detected by an amplitude detector 7 and it is decided that the oscillation is started with said amplitude larger than a fixed level. Then a signal is sent to the switch 6 to change its connection to the side B from the side A to obtain an oscillation circuit having an amplifier of the 1-stage constitution of an inverter. Thus the oscillation is continued. Thus it is possible to obtain an extremely stable oscillation frequency against the variation of the ambient temperature and the power supply voltage although the amplifying gain is set at a low level.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to excavation circuits, and more particularly to excavation circuits using inverter gates and mechanical oscillators (eg, crystal oscillators).

2. Description of the Related Art The configuration of a conventional oscillation circuit of this type is shown in FIGS. 2 and 3, where l is an appropriate DC bias point (point D in FIGS. D and S) on the input side of the inverter gate. Feedback resistor Ry for setting, ko is the inverter gate, 3-piece mechanical oscillator (for example, crystal oscillator), da is the capacitor u+ connected to the input side of the inverter gate, r is connected to the output side of the inverter gate This is capacitor C2.

In the oscillation circuit shown in FIG. 2, the amplifier is composed of inverter gates/stages.

The oscillation principle of this oscillation circuit is shown in Fig.
is an amplifier t consisting of a resistor/and an inverter gate.
The output voltage of the inverter gate increases, and this output voltage is again applied to the mechanical resonator 3 (for example, a crystal resonator) in the same phase to maintain the vibration of the resonator.

In other words, excavation will continue.

In the oscillation circuit shown in FIG. 3, the amplifier is composed of three stages of inverter gates. The total loss principle of this oscillation circuit is shown in Figure S, which is similar to the oscillation principle in Figure 2 except that the amplifier 9 has a three-stage configuration instead of an inverter gate/stage.
They are exactly the same.

However, since the amplifier 9 has a three-stage inverter gate configuration, the amplification gain is high, and the inverter tag-81 shown in Figure 1 has a high amplification gain.
This has the advantage that excavation occurs more easily than in a staged oscillator circuit.

Problems to be Solved by the Invention The mechanical vibrator used in the above-mentioned oscillation circuit is as follows:
Crystal cameras with stable frequencies are currently in widespread use. Therefore, an oscillation circuit using a crystal resonator will be described below.

Recently, microcomputers such as CPUs (Cent
Processing Units) are becoming faster to operate, but in order to achieve this faster operation, a circuit that supplies a high-speed clock frequency with high frequency stability is required. come. but,
The frequency of the crystal oscillator is at most x in the fundamental mode
MHz, and in higher frequency bands, it is necessary to use an overtone mode (imaging mode several times the fundamental wave) transducer. If a relatively large high-frequency voltage is not applied, the problem arises that the device does not vibrate or vibrates in the fundamental mode.

Therefore, if an overtone mode sensor is used in the circuit shown in Figure 1 to obtain high frequencies, oscillation will not occur because sufficient amplification gain cannot be obtained with an amplifier with a single-stage inverter gate configuration. It has the disadvantage that it oscillates in the fundamental wave mode.

In addition, when using the overtone sensor shown in Figure 8.7, the amplifier is composed of three stages of inverter gates, so the amplification gain is very high, so the desired frequency can be adjusted. It will be damaged. However, since the inverter gate, which is a semiconductor element, is connected in three stages, the oscillation frequency is greatly affected by fluctuations in the power supply voltage and ambient temperature, and has the disadvantage that a stable frequency cannot be obtained. ing.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional technology, and therefore, an object of the present invention is to easily emit and lose at a desired frequency, and to maintain stability, no matter what kind of mechanical vibrator is used. The object of the present invention is to provide a novel oscillation circuit that can obtain a frequency.

Means for Solving the Problems In order to achieve the above object, the oscillation circuit according to the present invention prepares an amplifier with an inverter gate/stage and a three-stage inverter gate configuration, and adjusts the oscillation frequency provided at the output terminal. The amplitude detection device is configured to monitor the magnitude of the amplitude (pressure) and select the gain of the amplifier by switching between an inverter gate/stage and a three-stage amplifier according to the magnitude, and thus, It is characterized by easily obtaining a stable oscillation frequency.

Embodiment Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings.

An embodiment of an oscillation circuit according to the present invention is shown in FIG. 1st
In the figure, reference number l is a feedback resistor (RF) for applying an appropriate DC bias (point D in Figures 7 and 3) to the input side of the gate of the inverter gate amplifier, and ko is the inverter gate. , 3 is a mechanical oscillator (for example, a crystal camera), and q is a capacitor connected to the input side of the gate (
CI), & is the capacitor (C
;2), A is a switch for switching and connecting an amplifier with a seven-stage inverter gate configuration and an amplifier with a three-stage configuration;
1 and 2 respectively show devices for detecting the magnitude of the amplitude of the oscillator output and sending a signal for controlling the switch 6.

Next, the operating principle of the oscillation circuit according to the present invention will be explained. When starting oscillation, the switch 6 in the figure is connected to the A side to create an oscillation circuit having a high gain amplifier with a three-stage inverter gate configuration, and the amplitude detection device 7 detects the amplitude of the oscillation frequency. Then, if the size exceeds a certain value,
Assuming that excavation has started, a signal is sent to the switch 6 to connect the switch from the A side to the B side 1/c, and the oscillation circuit is switched to an oscillation circuit having an amplifier with a seven-stage inverter configuration to continue oscillation. At this time, although the amplification gain becomes low, it is possible to obtain an oscillation frequency that is very stable against fluctuations in power supply voltage and ambient temperature.

In addition, if oscillation is about to stop for some reason, it can be detected by the amplitude detection device 7, and the switch 6 can be connected to the A side to increase the gain of the amplifier and cause good oscillation to occur again. .

As described in detail of the invention, using the oscillation circuit according to the invention,
Even when the power supply voltage is low and the frequency is high, good oscillation can be easily caused and a stable oscillation frequency can be supplied.

[Brief explanation of drawings]

Fig. 1 is a block configuration diagram showing an embodiment of an oscillation circuit according to the present invention, Fig. 2 is an oscillation circuit diagram with a conventional seven-stage inverter gate configuration, and Fig. 3 is an oscillation circuit with a conventional three-stage inverter gate configuration. 1 and 2 are diagrams showing the principle of amplification operation using a seven-stage inverter gate configuration, and FIG. 5 is a diagram showing the principle of amplification operation using a seven-stage inverter gate configuration. /... Feedback resistor (RF), Co... Inverter gate, 3... Mechanical vibrator, Hiro... Input side capacitor (
C1),! ...Output side capacitor (C2), A...
Changeover switch, r...amplitude detection device, g...amplifier with one-stage inverter gate configuration, q...amplifier with three-stage inverter gate configuration, A, B, C...connection terminal, D
...Bias point, 0...Output terminal Patent applicant Japanese office A corporation representative Patent attorney Kumagai Zongken also Fig. 3 Input voltage V111 Fig. 4

Claims (1)

[Claims] An oscillation circuit using an inverter gate and a mechanical resonator (for example, a crystal resonator), characterized in that an internal amplifier can be switched between a three-stage inverter gate configuration and a one-stage inverter gate configuration using a switch.