A sampled-data feedforward programmable time-mode comb filter

Abstract

In this work, a sampled-data feedforward comb filter suitable for time-mode signal processing (TMSP) is proposed. In the proposed system the input voltage is sampled and converted to a pulse-width (PWM); the pulse width is proportional to the input amplitude. The pulse width is the quantity which is being processed by the time-mode feedforward comb filter. Both input and output are synchronous with the sampling clock. The benefits of the proposed filter topology are (a) the modular and (b) hierarchical design which can be dealt with as a pure digital comb filter implementation counterpart. The frequency response of the proposed filter is digitally programmable. As a result, this filter can be used as building block for the implementation of higher-order time-mode systems. The comb filter was designed and verified through post-layout simulations in TSMC 65 nm technology process. The sampling rate was 5 MHz, the voltage supply was 1.2 V, consuming 540 μW for the use of 9-unit delay tap network and occupying a total area of 254 μm × 160 μm.