A cascaded ΔΣ modulator with low voltage and low power using inverter for integration is presented to solve the requirement for high-supply voltage and high-gain operational transconductance amplifiers(OTA)in integrators. The cascaded structure with interstage feedback circumvents the mismatch problem in conventional cascaded structure
and reduces the design demands of analog integrators
without need of high-gain OTA under high supply voltage for the accuracy of the transfer function. A two-stage cascaded fourth-order ΔΣ modulator is designed using 0.5 μm complementary-metal-oxide-semiconductor(CMOS)process
and class-C inverters are utilized for integration to reduce power consumption and chip area. Simulation results under a supply voltage as low as 1.4 V show that the proposed modulator achieves 99.8 dB peak signal-to-noise-plus-distortion-ratio(SNDR)and 58.6 μA current consumption in the case of an oversampling ratio of 128 and a 3.9 kHz signal bandwidth
while the modulator only occupies a chip area of 858 μm×525 μm. The proposed modulator has advantages of low supply voltage and low power consumption
and is suitable for high-resolution processing of low-frequency signals.
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