A 200 M sample/s 10 mW switched-capacitor filter in 0.5 μm CMOS technology

Abstract

Precise opamp gain (POG) design allows high-frequency SC filters using high-bandwidth op amps with low but precisely-known dc-gain, whose value is used as a parameter in the capacitor sizing. Using an op amp dc-gain Ao with a maximum relative deviation /spl epsi/, this concept allows the same performance accuracy obtained with standard design using an opamp with dc gain Ao//spl epsi/. In this work, using a standard 0.5/spl mu/m CMOS technology and 5V supply, 150MSample/s is achieved, consuming 20mW. The CMOS opamp dc-gain is set with a closed-loop gain-control circuit. In addition, the output dc-voltage is fixed by a CMOS circuit. This results in dc output voltage independent of technological variations, enabling rail-to-rail output swing.