GHz-range continuous-time programmable digital FIR with power dissipation that automatically adapts to signal activity

GHz-range applications that operate in a variety of signal situations and/or multiple standards require highly programmable responses that cannot be provided by analog circuits. Conventional digital solutions suffer from aliasing, thus requiring a complicated antialiasing filter and/or extremely high clock speeds with high power dissipation. An alternative is continuous-time (CT) DSP [1], which uses level-crossing sampling [2] but without a clock. It offers activity dependent power dissipation, is alias-free and has lower EMI emissions. This technique has so far been demonstrated in the voice band [3] but cannot be pushed beyond the MHz range because it involves extremely narrow pulse widths that cannot be handled by digital logic. This work bypasses this timing problem, enabling a five-orders-of-magnitude improvement in frequency capa bility compared to [3], thus making CT DSP a candidate for wideband GHz low dynamic-range applications, such as those found in pulse radio, spectrum sens ing, and channel equalization. Presented is a 3b 6-tap CT DSP system with wide programmability that is implemented in ST 65nm technology.