Reference loop for a digital-to-analog converter

摘要

An improved reference loop for a digital-to-analog converter (DAC) uses an approximate 50% duty cycle to improve the DC performance and the drift of the DAC at mid-scale. The 50% duty cycle also allows the DAC to provide the same performance over all outputs irrespective of the number of bits supplied to each input. The 50% duty cycle for the reference loop may be obtained from one of the DAC system outputs by forcing that output to supply a square wave output signal which may be used as input for the reference loop. The reference loop may alternatively be supplied by a DAC clock that is divided to obtain the desired 50% duty cycle input to the reference loop, in which case all outputs of the DAC are available for system output.