An elliptic continuous-time CMOS filter with on-chip automatic tuning

A voice-band continuous-time filter is described which was designed based on the technique of fully balanced networks and was fabrication in a 3.5-/spl mu/ CMOS technology. The filter implements a fifth-order elliptic low-pass transfer function with 0.05-dB passband ripple and 3.4 kHz cutoff frequency. A phase-locked loop control system fabricated on the same chip automatically references the frequency response of the filter to an external fixed clock frequency. The cutoff frequency was found to vary by less than 0.1% for an operating temperature range of 0-85/spl deg/C. The absolute value accuracy of the cutoff frequency was 0.5% (standard deviation). With /spl plusmn/5-V power supplies the measured dynamic range of the filter was approximately 100 dB.

[1]  P. Gray,et al.  Design techniques for MOS switched capacitor ladder filters , 1978 .

[2]  K.R. Rao,et al.  A novel "Follow the master" filter , 1977, Proceedings of the IEEE.

[3]  Yannis Tsividis,et al.  Continuous-time MOSFET-C filters in VLSI , 1986 .

[4]  V. R. Saari.  Low-Power High-Drive CMOS Operational Amplifiers , 1983 .

[5]  L.C. Parrillo,et al.  Twin-tub CMOS - A technology for VLSI circuits , 1980, 1980 International Electron Devices Meeting.

[6]  J. O. Voorman,et al.  Integration of analog filters in a bipolar process , 1982 .

[7]  M. Banu,et al.  Fully integrated active RC filters in MOS technology , 1983, 1983 IEEE International Solid-State Circuits Conference. Digest of Technical Papers.

[8]  Yannis Tsividis,et al.  On-chip automatic tuning for a CMOS continuous-time filter , 1985, 1985 IEEE International Solid-State Circuits Conference. Digest of Technical Papers.

[9]  P. R. Gray,et al.  Fully integrated analog filters using bipolar-JFET technology [active fifth order Chebyshev low-pass realisation] , 1978 .

[10]  P. R. Gray,et al.  High-frequency CMOS continuous-time filters , 1984 .

[11]  Yannis Tsividis,et al.  Detailed analysis of nonidealities in MOS fully integrated active RC filters based on balanced netwo , 1984 .

[12]  O. Wing,et al.  Ladder Network Analysis by Signal-Flow Graph-Application to Analog Computer Programming , 1956 .

[13]  J. Quartly,et al.  Gyrator video filter IC with automatic tuning , 1980, 1980 IEEE International Solid-State Circuits Conference. Digest of Technical Papers.

[14]  Yannis Tsividis.  Self-tuned filters , 1981 .