A programmable mixed-signal ASIC for power metering

A programmable mixed analog-digital integrated circuit for use in power-metering applications is described. The IC acquires analog input signals from three pairs of voltage and current sensors and provides outputs proportional to RMS voltages and currents: real, reactive, and apparent power; and power factor, phase angle, and frequency. Combinations of two of the metering functions may be computed simultaneously and outputs are provided in both bit-serial digital and pulse-width-modulated formats. Sensor and analog-to-digital converter errors are corrected using programmable digital signal processing. To achieve accurate operation over a wide, continuous range of frequencies. the IC measures the frequency of its input signals and adjusts filter characteristics and calibration coefficients accordingly. The device has been fabricated in a 5-V 1.5- mu m CMOS process and, with gain calibration alone, has achieved an absolute metering accuracy of 0.04%.<
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