JPH01300614A - Ring oscillator oscillating circuit - Google Patents

Abstract

PURPOSE:To eliminate the need for an externally mounted component even with LSI configuration by controlling an oscillating frequency of a ring oscillator by a gate voltage of a transistor(TR). CONSTITUTION:When a voltage between a gate terminal VP and a ground terminal VSS of P-channel MOS TRs 1, 2, 5, 6, 9, 10 is increased and a voltage between a gate terminal VN and a ground terminal VSS of N-channel MOS TRs 3, 4, 7, 8, 11, 12 is decreased, since the drain current of the TRs 1, 4, 5, 8-10 is decreased, the delay in one stage of inverter is increased and the oscillating frequency is lowered. That is, the oscillating frequency appearing at an output terminal OUT is controlled continuously by a voltage between the terminal VP and the ground terminal VSS and between the terminal VN and the ground terminal VSS. Thus, the necessity of an externally mounted component is avoided even with LSI processing.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an oscillation circuit whose oscillation frequency can be continuously controlled by a voltage other than the power supply voltage.

BACKGROUND OF THE INVENTION Conventional microprocessors and various logic circuits use oscillation circuits to generate clock signals and the like. However, when trying to generate a signal with a continuously variable frequency, variable resistors and variable capacitors are required, and these become obstacles to LSI implementation.

FIG. 5 shows a conventionally used circuit for generating a signal with a continuously variable frequency.

In FIG. 5, VDD is a power supply terminal, VSS is a ground terminal, and OUT is an output terminal. 13°15.17 is P
Channel type MO8 transistor, 14.16.18 is N
It is a channel type MOS transistor. Power supply terminal VDD
- Self-oscillation is performed by applying a power supply voltage between the ground terminals vSS and the variable resistor 19. The oscillation frequency can be controlled by the variable capacitor 20.

Problems to be Solved by the Invention However, the conventional circuit configuration described above requires a variable resistor and a variable capacitor to control the oscillation frequency. It had the disadvantage that it became an attached part. Furthermore, since operating variable resistors and variable capacitors involves mechanical movement, it lacks high speed, and controllability using other electronic circuits is also significantly inferior.

The present invention solves the above conventional problems, and is an oscillation circuit that does not require any external components even when implemented as an LSI, and whose oscillation frequency can be electrically controlled from other electronic circuits.

Means for Solving the Problems In order to achieve this object, the oscillation circuit of the present invention provides an oscillation circuit that operates between the source and power supply line of a P-channel MOS transistor of a CMOS inverter that constitutes a ring oscillator, and between the source and ground of an N-channel MOS transistor. P-channel type and N-channel type MOS are connected in series between the lines.
It has a CMOS inverter configuration in which transistors are connected and the gate voltages of these two transistors can be changed independently.

Effect: With this configuration, the oscillation frequency of the ring oscillator can be controlled by the gate voltages of the two newly added transistors, and no external components are required. Also,
Since it can be controlled electrically, it can be easily connected to other electronic circuits.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of an oscillation circuit in a first embodiment of the present invention. In Figure 1, 1,2°5.6,9.10
are P-channel MOS transistors, 3, 4.7, 8,
11 and 12 are N-channel type MOS transistors.

The operation of the oscillation circuit configured in this way will be explained.

In FIG. 1, a power supply voltage of 5V is applied between the power supply terminal VDD and the ground terminal VSS. P channel type MO
S transistor gate terminal VP - ground terminal vSS
When OV is applied between the gate terminal VN and the ground terminal vSS of the N-channel MOS transistor, this circuit becomes a circuit equivalent to a ring oscillator composed of three stages of inverters, and oscillates at a constant frequency. A signal appears at the output terminal OUT. If the delay of one stage of inverter is d seconds, the oscillation frequency fHz is determined by the following formula. When the voltage between terminal VN and ground terminal vSS is lowered, transistor 1.4,
Since the drain currents of 5, 8, and 9.10 decrease, the delay per inverter stage increases and the oscillation frequency decreases.

As described above, according to this embodiment, the oscillation frequency appearing at the output terminal OUT can be continuously controlled by the voltage between the terminal VP and the ground terminal vSS and between the terminal VN and the ground terminal vSS. Furthermore, since it is composed only of transistors, it can be easily incorporated into an LSI and does not require any external parts.

FIG. 2 shows a second embodiment of the invention. In FIG. 2, 21, 22, 25, 26, and 29 are P-channel type MOS transistors, and 23, 24, 27, and 28.30 are N-channel type MO8 transistors. Between VP and VSS, VN
The oscillation frequency can be controlled by the voltage between -VSS. Furthermore, oscillation can be stopped by setting OV between R and VSS.

FIG. 3 shows a third embodiment of the invention. In FIG. 3, 31a and 31b are multiplexers, and 32a is an oscillation circuit according to the second embodiment of the present invention.

VPI ~ VP4°V depending on input signals from So and Sl
Inputs from NI to VN4 can be switched.

Since the oscillation circuit of the present invention does not require mechanical operations such as operating variable resistors and variable capacitors, by adopting the configuration as in the third embodiment, frequency control can be performed at high speed.

In addition, So, SL and S2. If S3... is added, more voltages can be selected and the resulting frequencies will be more diverse.

FIG. 4 shows a fourth embodiment of the present invention. In FIG. 4, 33a and 33b are DA converters, and 32b is an oscillation circuit in the second embodiment.

Input a digital signal from IN. If quantization is performed using 8 bits, 256 levels of frequency can be obtained.

Even in this case, frequency control can be performed at high speed.

Effects of the Invention As described above, in the present invention, since the oscillation frequency can be controlled by voltage, there is no need for external components even if it is implemented as an LSI, and control from other electronic circuits can be performed at high speed.

[Brief explanation of the drawing]

1 to 4 are circuit diagrams or block diagrams of oscillation circuits in first to fourth embodiments of the present invention, and FIG. 5 is a circuit diagram of a conventional oscillation circuit. 1.2,5,6,9.10.13,15.17゜21.
22.25.26.29...P channel type MO
S transistor, 3, 4, 7, 8, 11.12°14.
16.18, 23, 24, 27, 28.30...
・N-channel MOS transistor, 19...
Variable resistor, 20... Variable capacitor, 31a. 31b...Multiplexer, 32a, 32b.
...Oscillation circuit in the second embodiment of the present invention, 3
3a. 33b...DA converter. Name of agent: Patent attorney Toshio Nakao and one other person Figure 1 Figure 2

Claims (1)

[Claims] A source of a first P-channel MOS transistor is connected to a power supply line, a drain of the first P-channel MOS transistor is connected to a source of a second P-channel MOS transistor, and a source of the first P-channel MOS transistor is connected to a power supply line. M.O.S.
The drains of the transistors are commonly connected to the drains of the first N-channel MOS transistors, the sources of the first N-channel MOS transistors are connected to the drains of the second N-channel MOS transistors, and the drains of the second N-channel MOS transistors are connected in common. The source of the channel type MOS transistor is connected to a ground line, the gate of the second P channel type MOS transistor and the gate of the first N channel type MOS transistor are commonly connected, and the second P channel type MOS transistor is connected to the ground line. A common gate and common drain of the transistor and the first N-channel MOS transistor,
respectively, and the first P
The gate of the channel type MOS transistor and the second
A ring oscillator type oscillator circuit equipped with a CMOS inverter configured to be able to independently control each voltage at the gate of an N-channel MOS transistor.