My copy of Gardner's "Phaselock Techniques" arrived today. Page 10 fig. 2.2, I'll try some asci art, all opamps are inverting.
a.)
---R1---+------ | R 2 | C
--------+------
b.) +-R2-C-+ | |\ |
--R1-+-| >--+ |/
c.) +-R2--+ | |\ | +-R1-+-| >-+--+
--+ |/ | | +--C--+ ->these go into another opmap summer. | | |\ | | +-R1-+-| >-+--+ |/
I've been using circuit c.) for control loops, sometimes with a derivative stage. I never realized (was shown)* circuit b.) does the same thing. Is there any down side to b.)? Capacitor wind-up? I usually keep R1=R2 in c.) (with the integrating resistor being different maybe.)
George H.
*well there was a B. Pease "what's all this.." about control loops and cruise control.