Programmable PD servo-compensator

摘要

A programmable PD servo compensator has the transfer function of the combination of a standard PD compensator in tandem with a second order low pass filter. The programmable PD servo compensator consists simply of a biquad filter having a single complex zero and a pair of conjugate complex poles. This servo compensator is comprised of two tandem connected operational amplifiers, each with a capacitor connected output to input across it. The tandem connection is effected by one switched-capacitor resistor between the output of the first amplifier to the input of the second. Another switched-capacitor resistor is connected between the PD compensator input and the input of the first amplifier. Yet another switched capacitor is connected between the PD compensator output and the input of the first amplifier. Additionally, a poles Q-programming circuit branch includes a digitally-programmable capacitor array, and a zero programming circuit branch includes another digitally-programmable capacitor array connected in the filter for determining the S-plane position of the zero and determining the relative gains of the proportional and derivative components of the PD compensator output signal. This is therefore an analog-signal handling servo compensator with digital programmability and having high speed, stability and versatility.