The integration method of linearizing exponential waveforms

Abstract

The exponential response of the simple CR “integrator” to a step impulse e.m.f. is shown to differ from the exactly linear rise required in many electronic applications by an “error” voltage which is proportional to the integral of the exponential output. Three methods are given of adding a second CR integrating section in such a manner that a close approximation to the error voltage is produced at the correct amplitude and superimposed on the output of the basic integrator. Each corrected network has an LR equivalent and may be arranged for voltage or current excitation. A number of suitable practical arrangements are given for each of the following applications:—(i) Linear sawtooth voltage wave generation,(ii) Waveform linearization in time base voltage amplifiers,(iii) Linear sawtooth current wave generation, as in electromagnetic time bases used for television reception.In the last application effective, superposition of the principal current and its integral is achieved by the use of split deflecting coils.