Title :
Integrated universal biquad based on triple-output OTAs and using digitally programmable zeros
Author :
Al-Hashimi, B.M. ; Dudek, F. ; Moniri, M. ; Living, J.
Author_Institution :
Sch. of Eng. & Adv. Technol., Staffordshire Polytech., Stafford, UK
fDate :
6/1/1998 12:00:00 AM
Abstract :
The authors describe how triple-output OTAs facilitate the development of a new current-mode universal biquad configuration capable of generating various filter transfer functions using digitally programmable zeros. This is achieved without excessive use of active devices and without changing the biquad topology. The biquad zeros may be independently programmed using four switches producing the following filtering functions: lowpass, highpass, bandpass, notch, allpass and lowpass notch. Further advantages of the biquad are (ω0 and Q) electronic tunability, low sensitivity and ease of design. Fabricated in a 0.8 μm double-metal, double-poly CMOS process, the universal biquad occupies an active chip area of 0.6 mm2. For demonstration purposes, simulated and measured results of voltage tunable lowpass and bandpass filters over the frequency range of 0.7 MHz to 4 MHz are included
Keywords :
CMOS analogue integrated circuits; all-pass filters; band-pass filters; biquadratic filters; circuit tuning; continuous time filters; high-pass filters; low-pass filters; notch filters; operational amplifiers; poles and zeros; transfer functions; 0.7 to 4 MHz; 0.8 micron; active chip area; allpass filters; bandpass filters; biquad topology; current-mode universal biquad configuration; digitally programmable zeros; double-metal double-poly CMOS process; electronic tunability; filter transfer functions; highpass filters; lowpass filters; notch filters; sensitivity; triple-output OTAs; voltage tunable filters;
Journal_Title :
Circuits, Devices and Systems, IEE Proceedings -
DOI :
10.1049/ip-cds:19981990