A flexible, clockless digital filter

This paper presents a clockless digital filter able to process inputs of different rates and formats, synchronous or asynchronous, with no adjustment needed to handle each input type. The 16-tap, 8-bit FIR filter, integrated in a 130 nm CMOS process, includes on-chip automatic delay tuning. The chip was used as part of a ADC/DSP/DAC chain which, unlike the case with conventional, clocked systems, maintains its frequency response intact when the sample rate changes. For certain inputs, the system has signal-to-error ratio which exceeds that of clocked systems.