Low-voltage high-speed current-mode continuous-time IC filters with orthogonal /spl omega//sub 0/-Q tuning

The design of fully differential high-frequency continuous-time current-mode filters is presented. A universal biquad is constructed from two basic building blocks, lossless and lossy differential current-mode integrators, Pole frequency /spl omega//sub 0/ and quality factor Q are tuned orthogonally by means of a translinear circuit. The design is illustrated on a 200-MHz fifth-order cascade low-pass filter. The tuning scheme is used to switch the transfer function electronically from a Butterworth to a Bessel characteristic. The proposed circuits use a single-ended supply that can be as low as 1.5 V with no special technology required. The design was implemented in an 8-GHz bipolar process.