A 20μW 95dB DR Single-Bit Delta-Sigma Modulator for Portable Measurement Applications

A low power high performance Delta-Sigma modulator for portable measurement applications is presented in this paper. To reduce the power consumption and ensure high performance, a comprehensive system-level design adopting a new method to determine the DC gain value of Operational Transconductance Amplifier (OTA) and considering the effect of 1/f noise is introduced. Besides, a novel power efficient current mirror Class-AB OTA with a fast-settling less-error switched-capacitor common-mode feedback (SC CMFB) circuit is proposed in this design. And the bottom terminal parasitic-effect of Poly-Insulator-Poly (PIP) capacitors is also considered. Therefore, about extra 20% of the capacitance is added to the total capacitance load. In addition, an area-efficient power-efficient resonator is adopted to realize a coefficient of 1/90 for 50% power and 75% area cost reduction over the conventional design. The chip is implemented in a low cost standard 0.35μm CMOS. Its total power is only 20μW at a 1.5V supply, and the measured Dynamic Range (DR) is 95dB over the 1 kHz bandwidth. The designed modulator shows very high Figure-of-Merit (FOM) among the recent low power high performance modulators. Keywords–low power, high performance, Delta-Sigma modulator, switched capacitor circuits