Extra loop delay compensation for hybrid delta-sigma modulators

In this paper, an extra loop delay compensation technique for hybrid delta-sigma modulators (DSM) is proposed. The hybrid DSM replaces analog components with digital circuitry by carrying out A/D conversion in the middle stage of a loop filter. The hybrid DSM is a small-sized prototype that realizes A/D conversion with low power consumption. In many cases, A/D converters exhibit latency, which becomes an extra loop delay for the hybrid DSM. This extra delay changes the noise transfer function (NTF), resulting in loop instability or reduced resolution. The proposed method compensates for the extra delay by applying a noise coupling technique. This compensation achieves the desired NTFs and enhances the loop stability and resolution.