SC realization of antialiasing CCIR-601 video filters

Switched-capacitor circuits as discrete-time analog devices are especially suited for the signal processing tasks occurring when interfacing analog and digital systems. The major obstacle towards the use of standard CMOS technology for SC video filters is the limited speed of high-gain CMOS op-amps. This limitation however can be overcame with some design ingenuity, as in the application considered in this work. Recommendation CCIR-601 prescribes to prefilter luminance and color-difference signals with filters characterized by tight group-delay specifications. In this work we consider the realization of the color difference prefilter H/sub a/(s), which is currently available only in discrete-component (and therefore very expensive) implementations, with an equivalent system formed by the cascade of two integrated filters, namely a continuous time filter H/sub 1/(s) and a SC filter H(z). This type of implementation can be applied to the luminance prefilter as well. Since CCIR Recommendation 601 prefilters are at the front-end of every digital television system, there are opportunities for their large-scale production within which the economical advantages of the proposed integrated solution are apparent.<
>