A MOSFET-only continuous-time bandpass filter

A MOSFET-only filter is described which employs an amplifier-regulated cascode structure to realize both conductance and transconductance, while the required capacitors are realized by MOSFET gate capacitance. Distortion due to mobility degradation and MOSFET capacitor nonlinearity is analyzed, as is the effect of finite gain-bandwidth product of the regulating amplifiers on the filter's linearity and high frequency performance. A prototype second-order bandpass filter has a center frequency of 560 kHz, a third-order intermodulation of -41 dB for 0 dBm input and a dynamic range of 60 dB. It consumes 2.5 mW from a 5 V supply and occupies 0.18 mm/sup 2/ in a 1-/spl mu/m digital CMOS technology.

[1]  David J. Allstot,et al.  CMOS continuous-time current-mode filters for high-frequency applications , 1993 .

[2]  A. T. Behr,et al.  Harmonic distortion caused by capacitors implemented with MOSFET gates , 1992 .

[3]  G. Geelen,et al.  A fast-settling CMOS op amp for SC circuits with 90-dB DC gain , 1990 .

[4]  Guido Torelli,et al.  CMOS triode-transistor transconductor for high-frequency continuous-time filters , 1994 .

[5]  D. J. Allstot,et al.  Low-power CMOS continuous-time filters , 1996 .

[6]  Thomas Burger,et al.  A 100 dB, 480 MHz OTA in 0.7 /spl mu/m CMOS for sampled-data applications , 1996, Proceedings of Custom Integrated Circuits Conference.

[7]  Z. Czarnul.  Novel MOS resistive circuit for synthesis of fully integrated continuous-time filters , 1986 .

[8]  Andreas Kaiser,et al.  A 2- mu m CMOS fifth-order low-pass continuous-time filter for video-frequency applications , 1993 .

[9]  J. Silva-Martinez,et al.  Design techniques for high-performance full-CMOS OTA-RC continuous-time filters , 1992, IEEE Journal of Solid-State Circuits.

[10]  A. Wyszynski,et al.  Low-voltage CMOS and BiCMOS triode transconductors and integrators with gain-enhanced linearity and output impedance , 1994 .

[11]  Zdzislaw Czarnul,et al.  A low-voltage highly linear multiple weighted input CMOS transconductor , 1995 .

[12]  J. L. Pennock.  CMOS triode transconductor for continuous-time active integrated filters , 1985 .

[13]  Qiuting Huang.  A MOSFET-only continuous-time 560 kHz tunable bandpass filter , 1995, Digest of Technical Papers., Symposium on VLSI Circuits..

[14]  Y. Tsividis.  Operation and modeling of the MOS transistor , 1987 .

[15]  Yannis Tsividis,et al.  Transistor-only frequency-selective circuits , 1990 .