  Analog-to-digital converters (ADCs) provide the link between continuous-time
signals and their discrete-time counterparts, and the Shannon-Nyquist sampling
theorem provides the mathematical foundation. Real-world signals have a
variable amplitude range, whereas ADCs, by design, have a limited input dynamic
range, which results in out-of-range signals getting clipped. In this paper, we
propose an unlimited dynamic range ADC (UDR-ADC) that is based on the modulo
operation (self-reset feature) to alleviate the problem of clipping. The
self-reset feature allows for wrapping of the input amplitudes, which preserves
the input dynamic range. We present the signal model and a reconstruction
technique to recover the original signal samples from the modulo measurements.
We validate the operation of the proposed ADC using circuit simulations in 65
nm complementary metal-oxide-semiconductor (CMOS) process technology. The
validation is supplemented by a hardware prototype designed using discrete
components. A performance assessment in terms of area, power requirement, and
the signal-to-quantization-noise ratio (SQNR) shows that the UDR-ADC
outperforms the standard ones.
