A New Transistor Square-Wave Generator Using Two Regenerative Switches

The operation and performance of a new type of circuit for square-wave generation is presented. The circuit is based on the application of two identical regenerative switches using complementary transistors, the operation of which is controlled by a single timing capacitor. Rise and fall times of the output pulses can be made to depend almost entirely on the switching speed of the transistors, and are independent of the values of the elements used in the timing network. The frequency of oscillation can be varied continuously or in steps over a wide range of frequencies by changing one parameter only. With silicon planar transistors used in the regenerative switches, the temperature stability is quite satisfactory, but a simple method for further increase in temperature stability is also discussed. The capacitive (or resistive) loading of the output terminals does not affect the frequency of oscillation. These features make the circuit described very useful in many applications, and particularly in the design of wide-range square-wave generators. An experimental model of the circuit covering the frequency range from 1 Hz to 10 MHz has been built and some results of measurements are presented.