A 99-dB DR Fourth-Order Delta-Sigma Modulator for 20-kHz Bandwidth Sensor Applications

A fourth-order single-bit delta-sigma modulator is presented for sensor applications. The loop filter is composed of both feedback and feedforward paths, and the modulator is implemented using fully differential switched-capacitor techniques. A test chip was fabricated in a 0.18-mu m standard complementary metal-oxide semiconductor (CMOS) process. The chip core area is 1.22 mm(2), and its power consumption is 5.6 mW from a 3.0-V power supply. Measurement results show that a maximum 99-dB dynamic range is achievable at a clock rate of 3.2 MHz for the 20-kHz bandwidth. The designed chip is targeted for high-accuracy and wide-bandwidth sensor applications such as the resistor-based current sensors and the Hall-effect sensors in motor control systems.