A MOSFET-C VARIABLE EQUALIZER CIRCUIT WITH SIMPLE ON-CHIP AUTOMATIC TUNING

In this paper we report a MOSFET-C variable bump equalizer architecture in MOS technology. The architecture is "CAD-compatible" in that it has a fixed physical layout, yet it achieves independent and continuous programmability of the three equalizer parameters-omega-0 (center frequency), BW (bandwidth), and G (gain), using dc control voltages. To compensate for process and temperature variations the equalizer is tuned using a novel and simple master-slave automatic tuning scheme based on a switched-capacitor (SC) resistor in a gain control loop. The nonideal effects of the equalizer circuit due to finite amplifier gain bandwidth are studied and a test chip is fabricated using the MOSIS 2-mu-m p-well double-poly CMOS process to verify the performance. The equalizer with the automatic tuning circuit occupies 1.25 mm2 and operates from +/- 5-V power supplies. It dissipates 60 mW and provides wide tuning ranges for omega-0, BW, and G with less than 2.8% change in omega-0 over 40-degrees-C temperature range.