Title :
A tunable triode-MOSFET transconductor and its application to gm-C filters
Author :
De Lima, Jader A. ; Dualibe, Carlos
Author_Institution :
Dept. of Electr. Eng., Univ. Estadual Paulista, Sao Paulo, Brazil
Abstract :
A linear, tunable CMOS transconductance stage is introduced. Drain voltage of the input transistor operating in triode region is settled by a regulation loop and a first-order linear relationship between gm and a DC bias voltage is achieved. In addition to easy tuning, this technique offers circuit simplicity, wide dynamic range, high input and output impedances and low consumption. The transconductor is presented on both single-ended and fully-differential versions. A 3rd-order elliptical low-pass gm-C filter with a nominal roll-off frequency of 2 MHz is used as one example for the many applications of the proposed transconductor. SPICE data describe circuits performances and filter tunability. Passband is tuned at a rate of 2.36 KHz/mV and good linearity is indicated by a 0.89% THD for an 800 mVp-p balanced-driven input
Keywords :
CMOS analogue integrated circuits; active filters; circuit tuning; elliptic filters; integrated circuit design; low-pass filters; 3rd-order elliptical filter; DC bias voltage; filter tunability; first-order linear relationship; fully-differential version; gm-C filter application; high input impedance; high output impedance; linear CMOS transconductance stage; low power consumption; regulation loop; single-ended version; third-order low-pass filter; tunable triode-MOSFET transconductor; wide dynamic range; Circuit optimization; Dynamic range; Filters; Frequency; Impedance; SPICE; Transconductance; Transconductors; Tunable circuits and devices; Voltage;
Conference_Titel :
Circuits and Systems, 1999. ISCAS '99. Proceedings of the 1999 IEEE International Symposium on
Conference_Location :
Orlando, FL
Print_ISBN :
0-7803-5471-0
DOI :
10.1109/ISCAS.1999.780846
