A Micropower Square-wave Generator

Abstract

Micropower circuits are particularly important in military, biomedical and instrumentation applications because of their low power consumption, increased component density and reduced heat dissipation. Pulses generated with the conventional astable multivibrator using bipolar transistors at micropower levels are not of acceptable quality because of large rise and fall times brought about by high value resistors used in the circuit. With this in view, a micro power square-wave generator has been developed using a current source driven symmetrical differential amplifier as the basis. The use of cross-coupling capacitors with this circuit facilitates generation of square pulses with very small rise and fall times. The analysis of this circuit indicates that it is not necessary to have equal cross-coupling capacitors to generate square-wave pulses as long as the circuit is capable of relaxation oscillations. This paper gives the circuit analysis for the square-wave generator followed by experimental results.