300mV 50kHz 75.9dB SNDR CT ΔΣ Modulator with Inverter-based Feedforward OTAs

摘要

A low voltage low power continuous-time (CT) ΔΣ modulator is presented. To obtain a high linearity and power efficient modulator, a novel inverter-based feedforward OTA is proposed. A gain-enhancement technique is utilized to relax the load effect. With a novel complementary differential-difference common mode feedback circuit, the CMRR of OTA achieves 81.8 dB. The circuits were implemented in a 0.13 μm CMOS technology. The post layout simulation demonstrates that the modulator consumes 29.58 μW from a 300 mV supply and achieves a peak SNDR of 75.9 dB, a dynamic range of 79.5 dB, with a 50 kHz bandwidth under 64 oversampling ratio.