Title :
Low-power CMOS continuous-time filters
Author :
Zele, Rajesh H. ; Allstot, David J.
Author_Institution :
Radio Products Group, Motorola Inc., Plantation, FL, USA
fDate :
2/1/1996 12:00:00 AM
Abstract :
A design technique for low-power continuous-time filters using digital CMOS technology is presented. The basic building block is a fully-balanced integrator with its unity-gain frequency determined by a small-signal transconductance and MOSFET gate capacitance. Integrator excess phase shift is reduced using balanced signal paths, and open-loop gain is increased using low-voltage cascode amplifiers. Two-pole bandpass and five-pole lowpass ladder filters have been implemented in a 1.2 μm n-well CMOS process. The lowpass prototypes provided 300 kHz-1000 kHz bias-current-tunable -3 dB bandwidth, 67 dB dynamic range with 1% total harmonic distortion (THD), and 30 μW/pole (300 kHz bandwidth) power dissipation with a 1.5 V supply; the bandpass prototypes had a tunable center frequency of 300 kHz-1000 kHz, Q of 8.5, and power dissipation of 75 μW/pole (525 kHz center frequency) from a 1.5 V supply. The active filter area was 0.1 mm2/pole for both designs
Keywords :
CMOS analogue integrated circuits; Q-factor; band-pass filters; circuit tuning; continuous time filters; harmonic distortion; integrated circuit design; integrating circuits; intermodulation distortion; ladder filters; linear network synthesis; low-pass filters; radiofrequency filters; 1.2 micron; 1.5 V; 300 to 1000 kHz; 525 kHz; CMOS continuous-time filters; MOSFET gate capacitance; THD; active filter; balanced signal paths; bias-current-tunable bandwidth; design technique; digital CMOS technology; dynamic range; five-pole lowpass filter; fully-balanced integrator; ladder filters; low-power filters; low-voltage cascode amplifiers; n-well CMOS process; open-loop gain; total harmonic distortion; two-pole bandpass filter; Active filters; Band pass filters; Bandwidth; CMOS technology; Digital filters; Frequency; MOSFET circuits; Power dissipation; Prototypes; Transconductance;
Journal_Title :
Solid-State Circuits, IEEE Journal of
