A compact CMOS magnetic Hall sensor that includes both a Hall plate and readout circuit is proposed. In order to achieve a low-noise and low-power operation, the sensor employs a switched biasing amplifier with a chopper. The prototype has been implemented and fabricated in a high-voltage 0.18 m CMOS process and occupies 0.624 mm 2 . Owing to the switched biasing amplifier, the input-referred noise is reduced from 41 T Hz to 25 T Hz. The entire sensor consumes
mW with a 3.3 V supply voltage.Index Terms-1 f noise, CMOS, dynamic offset cancellation, magnetic Hall sensor, switched biasing amplifier.
A compact, low-power, single-loop third-order delta-sigma ( ) time-to-digital converter (TDC) for time-mode signal processing is presented in this brief. In general, a high-resolution TDC requires a cascadable time integrator to increase the order of the loop filter. However, implementing the time integrator has been very challenging owing to the difficulty in storing time information. In this brief, we present a low-power half-delay time integrator, which is simply composed of two AND gates, a charge pump, and a comparator. The proposed time integrator can be easily cascaded (serially connected) to implement a loop filter with high-order noise shaping. The prototype TDC fabricated in 0.11-μm CMOS process occupies an active area of 0.11 mm 2 , consuming 0.4 mW from a 1.2 V supply. It achieves the dynamic range of 81 dB over a signal bandwidth of 50 kHz, and the resolution of 4.7 ps over a measurable range of 39.06 ns, which is half the clock period.Index Terms-Delta-sigma ( ) modulator, high resolution, low power, time-to-digital converter (TDC).
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