A mixed-signal approach to high-performance low-power linear filters

We present a new approach to the design of high-performance low-power linea r filters. We use p-channel synapse transistors as analog memory cells, and mixed-signal circuits for fast low-power arithmetic. To demonstrate the ef fectiveness of our approach, we have built a 16-tap 7-b 200-MHz mired-signa l finite-impulse response (FIR) filter that consumes 3 mW at 3.3 V, The fil ter uses synapse pFETs to store the analog tap coefficients, electron tunne ling and hot-electron injection to modify the coefficient values, digital r egisters for the delay line, and multiplying digital-to-analog converters t o multiply the digital delay-line values with the analog tap coefficients. The measured maximum clock speed is 225 MHz; the measured tap-multiplier re solution is 7 h at 200 MHz, The total die area is 0.13 mm(2). We can readil y scale our design to longer delay lines.