| 摘要 |
<p>A generator for generating sawtooth waveforms having equal excursion of predetermined amplitude about a reference level, synchronized in frequency with the zero crossings of an AC signal. The AC signal is applied to a zero crossing detector whose resulting pulse output is connected to the input of a first integrating amplifier. The latter integrates in a first direction to produce at its output a rapid potential excursion in a first direction to a predetermined amplitude established by a Zener clamping circuit connected across the first integrator. Upon termination of each zero crossing pulse, a source of DC connected through a resistor to the input of the first integrator, produces integration in a second direction and a gradual change of integrator output in a second polarity direction until the occurrence of the next zero crossing pulse. The sawtooth output is connected to the input of a second integrating amplifier. The latter has a long RC time constant in respect to the frequency of the zero crossing detector pulses and provides an error signal output which after appropriate inversion is supplied to the input of the first integrating amplifier to provide the equal bi-polar excursions of the sawtooth waveform.</p> |
