SU470913A1 - Pulse generator - Google Patents

Description

The invention relates to a pulse technique and can be used as a source of rectangular oscillation pulses, whose frequency is stabilized by a quartz resonator and the formation of precise time intervals, time stamps, etc.

Known pulse generator, containing three series-connected inverter, a resistor connected between the input of the first and the output of the third inverter, a parallel-connected capacitor and a crystal resonator connected in parallel to the circuit formed by the third inverter and resistor.

However, the known generator is not suitable for use in a wide frequency range.

In order to expand the frequency range, the proposed generator contains an additional transistor, the emitter of which is connected to the input of the first inverter, the base to the resistor, and the collector is grounded.

FIG. 1 shows a functional diagram of the proposed pulse generator; in fig. 2 shows time diagrams of the relative collector output voltages of the transistor at various points in the generator circuit.

The generator of impulses contains inverters 1-3 connected in series, resistor

4, the feedback transistor 5, the capacitor 6, and the crystal resonator 7.

The pulse generator works as follows.

At the initial moment of time, the output potential of the inverter 2 has a high nagfing potential (with respect to the common point of the circuit), the output of the inverter 3 has a low potential (Fig. 2, d and e), the capacitor 6 is not charged. All the positive voltage at the output of the inverter 2 through the capacitor 6 is applied to the base of the transistor 5, which is a large resistance between the collector-emitter terminals connected in parallel with the input of the inverter 1, setting a voltage on it almost corresponding to the open input of the inverter 1 (Fig. 2, a and b). At the output of the inverter 1, as a result of the inversion of the signal,

low potential (Fig. 2, c), which maintains the indicated quasistable state of the circuit.

Next, the capacitor G is charged by the voltage from the output of the inverter 2 through the resistor 4 and the input resistance of the transistor 5. Due to the parallel connection of the capacitor 6 and the crystal resonator 7, the voltage at the base of the transistor 5 decreases oscillatory (Fig. 2a), which causes

reduction and a corresponding decrease

the output resistance of the transistor 5. With a sufficient decrease in the output resistance of the transistor 5, the inverter 1 goes into active mode, which is accompanied by a characteristic decrease in the voltage at its input at the end of the quasi-stable state (Fig. 2.6). Then the inverter 2 enters the active mode, the output of which through the capacitor 6 and the transistor 5 closes the positive feedback loop to the input of the inverter 1. The generator avalanche occupies another quasi-stable state in which the output of the inverter 2 is low potential and the output of the inverter 3 - tall. Through the open collector junction of transistor 5 and the output impedance of inverter 2, capacitor 6 is quickly discharged to zero potential at the base of transistor 5 (negative gaps, Fig. 2, a). The emitter potential monitors the base potential of the transistor 5. The last part of this quasistable state until the new conditions of the jump in the circuit of the inverter 1 is running in active mode. After the second jump, the processes in the circuit are repeated as described above.

Subject invention

A pulse generator containing three inverters connected in series, a resistor connected between the first input and the output of the third inverter, a parallel-connected capacitor and a crystal resonator connected in parallel to the circuit formed by the third inverter and the resistor, in order to extend the frequency range, the generator contains an additional transistor, the emitter of which is connected to the input of the first inverter, the base to the resistor, and the collector is grounded.

Pete

ig.1

FIG. 2