Y. W. Li, K. L. Shepard, and Y. P. Tsividis, “A continuous-time programmable digital FIR filter” IEEE Journal of Solid-State Circuits, November, 2006

In this paper, we describe the design and implementation of a continuous time finite-impulse-response processor chain, which includes a 6-bit asynchronous ADC, an asynchronous digital core, and an 8-bit asynchronous DAC designed in TSMC 0.25- m technology. The continuous-time, discrete-amplitude systems combine benefits associated with analog and digital systems. Discrete-amplitude representations leverage the noise immunity and robustness of digital implementations. Continuous-time, nonsampled operation prevents aliasing and reduces the in-band quantization noise associated with the aliasing of subharmonic components. We present measurement results demonstrating an audio low-pass filter with a bandwidth of 6.0 kH.