SU834841A1 - Pulse generator - Google Patents

Description

(54) PULSE GENERATOR

I

The invention relates to microelectronics, in particular, to the design of generators on MOS transistors.

Known pulse generator containing a capacitor, the first and second resistors, the first and second MOS transistors, the capacitor 1.

However, in a number of cases when it is necessary to control the generation frequency, in particular, when controlling the bias voltage or stabilizing it when other technological factors change, this scheme does not have this capability. To control the generation frequency, neither the RC capacitance value control nor the resistor magnitude control can be applied, which is related to the features of these elements in the integrated design. In particular, the use of a MOS transistor as a resistor in controlling its resistance leads to a violation of the duty cycle of the generated pulses.

The purpose of the invention is to expand the functionality of the device.

The goal is achieved by the fact that in a pulse generator containing a capacitor, the first and second resistors, the first and second MOS transistors, the drain of the first MOS transistor is connected to the source of the second, the drain of which through the first resistor is connected to the power supply and the gate of the second MOS transistor, the gate of the second MOS transistor is connected through a capacitor to a common bus, a third MOS transistor and a variable resistor are inserted, the source of the third MOS transistor connected to the drain of the first MOS transistor, and Thief - second MOPtranzistora to drain, and the drain to a power schine, MOPtranzistora first gate connected to the gate of the second MOPtranzistora and MOPtranzistora first source through a variable resistor connected

 to common shine.

In the proposed generator, the first and second resistors are made in the form of MOS transistors in a diode connection.

In addition, the variable resistor is implemented in the form of a MOS transistor, the gate of which is connected to the control voltage terminal.

The drawing shows a schematic diagram of the proposed device.

In the device, the transistor 1 is a load element of the hysteresis switch circuit, containing, in addition, the main transistor 2, the key transistor 3, the feedback element transistor 4. The gates of transistors 2 and 3 are interconnected, and the transistor 5 acting as a resistive element RC-n, eno4KH, with the output of switch 6. Between the gate of transistor 3 and a zero width 7 is connected a capacitor 8, which forms an integrating RC-chain with transistor 5. The output of the switch 6 is connected to the gate of the feedback transistor 4 connected between the power line 9 and the drain of the transistor 3, the source of which is connected to the zero line 7 via an additional transistor 10 that serves to control the width of the hysteresis loop.

The device works as follows.

The hysteresis switch formed by the transistors 1-3, due to the feedback transistor 4, has a hysteresis type of dependence of the input (on the gate of the transistor 2) and output (on the drain of the same transistor) voltages. The voltage from the switch output is fed to its input through an integrating RC-chain (on elements 5 and 8), as a result of which a generation occurs, the frequency of which is determined by the time required to change the voltage on the input of the switch (i.e., capacitor 8 ) from the magnitude of the opening to the magnitude of the closing and vice versa. This time depends on both the parameters of the RC chain and the difference in the values of the voltage of opening and closing of the switch. The greater this difference, i.e. the wider the hysteresis loop, the longer the time the switch is in the open and closed state, i.e. the longer the generation period.

To turn on the switch, it is necessary that the voltage across the gate of transistor 2 exceeds its source voltage by the amount of the threshold voltage. Thus, the switch-on voltage of the switch is determined by the voltage at the source of the transistor 2. Moreover, this voltage depends, in particular, on the resistance of the transistor 10, with an increase in which requires a higher voltage at the input to open the switch and vice versa. Changing the voltage at the gate of the transistor 10 in a certain way, changing the voltage at the source of the transistor 2, i.e. changing the width of the hysteresis loop, thus controlling the generation frequency. In this case, the duty cycle of the generated pulses does not change.

Claims (3)

1. A pulse generator containing a capacitor, the first and second resistors, the first and second MOS transistors, the drain of the first MOS transistor is connected to the source of the second, whose drain is connected to the power bus through the first resistor and to the gate of the second MOTTransistor, the gate A second MOS transistor is connected via a capacitor to a common bus, characterized in that, in order to expand its functionality, a third MOS transistor and a variable resistor are inserted, the source of the third MOS transistor connected to MOPtranzistora first current, its gate - to the drain of the second MOPtranzistora and drain - a power bus, a first gate connected to the gate MOPtranzistora second MOPtranzistora and MOPtranzistora first source through a variable resistor connected to the common schine. 2. The generator according to claim 1, characterized in that the first and second resistors are made 5 in the form of a MOS transistor in a diode connection. 3. Generator on PP. 1 and 2, characterized in that the variable resistor is made in the form of a MOS transistor, the gate of which is connected to the control voltage bus. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 661721, cl. H 03 K 3/28, 23.02.77 (prototype).