Reducing the temperature effect on a CMOS transconductance and its application in g/sub m/-C filters

A new negative feedback technique is applied to stabilize changes in the transconductance of a CMOS operational transconductance amplifier (OTA) with temperature variations over the industrial range of -30/spl deg/C to +85/spl deg/C. Since OTAs are used as the basic building blocks in various g/sub m/-C filters, stabilizing the transconductance brings stability in the frequency and quality factor of the filters built from these OTAs. To validate this notion, a second order band-pass filter with 10 MHz center frequency has been built with the temperature stabilized OTAs. The whole system has been implemented in TSMC 0.18 /spl mu/m CMOS technology available through the Canadian Microelectronics Corporation (CMC) and tested in the laboratory. The experimental results show close agreement with the theoretical expectations.

[1]  R. Schaumann,et al.  Design of a 4-MHz analog integrated CMOS transconductance-C bandpass filter , 1988 .

[2]  Rolf Schaumann,et al.  Automatic tuning of frequency and Q-factor of bandpass filters based on envelope detection , 1998, ISCAS '98. Proceedings of the 1998 IEEE International Symposium on Circuits and Systems (Cat. No.98CH36187).

[3]  Yuhua Cheng,et al.  The influence and modeling of process variation and device mismatch for analog/rf circuit design , 2002, Proceedings of the Fourth IEEE International Caracas Conference on Devices, Circuits and Systems (Cat. No.02TH8611).