2D video rate SC FIR filters based on analog RAMs

Monolithic CMOS analog implementations of video systems are extremely attractive because of their low area and power requirements. Switched-capacitor circuits may advantageously replace many current digital solutions of video systems. However, special care must be used in order to handle, with standard CMOS technology, the problems related to the broadband characteristics of video systems. Moreover, two-dimensional (2-D) filters require long delay lines, which are not easily implementable in the analog domain. Therefore, new design solutions must be developed, such as the architecture based on analog random-access memories for 2-D video-rate switched-capacitor finite-impulse response (FIR) filters, proposed in this work. This structure can be optimized with respect to area requirements and precision requirements, because it allows the exploiting of impulse-response symmetries of linear-phase FIR filters. The characteristics and the feasibility of the proposed design solution are demonstrated in the design of a 2-D low-pass filter for picture-in-picture resizing.