Improved SQNR and MSA in Incremental <inline-formula> <tex-math notation="LaTeX">$\Delta \Sigma$ </tex-math> </inline-formula> Modulators by Using a Recuperation Phase

Abstract

This brief presents a system-level technique that is capable of enhancing the efficiency of high-resolution incremental delta sigma (I-ΔΣ) modulators. With little additional effort in circuitry it is possible to make use of a recuperation phase, in which the I-ΔΣ modulator's input is periodically tied to a defined reference. In these phases, the modulator is given time to adjust its residual error to a minimum. This method is capable of increasing the maximum stable amplitude as well as the signal-to-quantization-noise ratio. Thus, this technique is especially valuable for high-resolution ADCs employing higher order modulators, as an increase in these measures directly affects power requirements. The method is analytically derived and exemplarily simulated. Furthermore, a circuit-level simulation in a 180-nm CMOS technology is presented to validate the results.