Invention Grant
US07884747B2 Digital to analog converters having circuit architectures to overcome switch losses 有权
具有电路架构以克服开关损耗的数模转换器

Digital to analog converters having circuit architectures to overcome switch losses
Abstract:
A digital to analog converter (DAC) includes a pair of operational amplifiers each having a first input coupled to a respective high or low reference voltage. The DAC includes a plurality of switch-controlled cells, each of which includes a resistor and two force/sense switch pairs. Within each cell, all four switches are coupled to the resistor. A first force switch is coupled to an output of a first op amp and an associated sense switch is coupled to an inverting input of the first op amp. A second force switch is coupled to an output of a second op amp and an associated sense switch is coupled to an inverting input of the second op amp. Thus, the force switches provide selectively conductive paths to permit either op amp to drive a given cell. When an op amp drives particular cells, sense switches generate multiple a feedback paths to the driving op amp, which permits the op amp to drive the selected cell resistors at voltages that overcomes any voltage losses induces by associated force switches, and cancels the effect of any variation in the voltage losses induced by different force switches. The switch-controlled cells find application in a variety of DAC architectures, including binary weighted R2R architectures, equally-weighted segmented architectures or hybrid architectures that blend principles of R2R and segmented architectures.
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