A fully-integrated continuous-time programmable CCIR 601 video filter

Digitizing video signals requires high-order anti-aliasing filters that handle large signal swings with low distortion. CCIR601 standards recommend the equi-ripple gain and group delay characteristics for filtering NTSC and PAL signals. Currently, these characteristics are approximated by expensive hybrids that are not programmable for various applications. This paper introduces a method for integrating such filters using current-mode transimpedance-based structures. A single-chip solution demonstrated here matches the requirements with less than /spl plusmn/0.25 dB gain ripple, /spl plusmn/20 ns group delay variation in the passband, and more than 40 dB attenuation in the stop band. The cut-off frequency, nominally set at 5.5 MHz, is continuously programmable over a decade. The IC can drive 2 Vpp signals into 75 /spl Omega/ load drawing 35 mA quiescent current. Comparable integrated filters using other techniques require substantially larger currents.