Systems and methods for auto gain control in Bi-CMOS digital to analog converters
AssigneeBroadcom Corporation
InventorChun-Ying Chen
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Abstract
The accuracy of output power in a digital-to-analog converter (DAC) is critical in certain applications. When bi-CMOS technology is used to implement a DAC, a number of factors affect the gain accuracy of the DAC. The present invention provides a circuit architecture to reduce the variation in these factors to ensure the accuracy of the output power of a DAC. The architecture comprises a bandgap portion, replica circuit and a DAC. The bandgap portion of the architecture provides a constant voltage, while the replica circuit provide a correct current to drive the DAC.
Claims11
A digital to analog auto gain control system, comprising:
- a constant voltage source;
- a replica circuit coupled to said constant voltage source, wherein said replica circuit includes resistors and a beta compensation module having bipolar devices;
- a digital-to-analog converter having bipolar devices coupled to said replica circuit, wherein said replica circuit provides a current to said digital-to-analog converter such that a voltage drop across said resistors tracks with a voltage of said constant voltage, wherein said beta compensation module compensates for a beta current loss in said digital-to-analog converter, wherein said beta compensation module bipolar devices mimic said digital-to-analog bipolar devices.
A method for auto gain control in a digital-to-analog converter system having a digital-to-analog converter that includes bipolar devices and a beta compensation module that includes bipolar devices, comprising:
- (a) receiving a digital code word;
- (b) generating a constant current source based on a constant voltage source;
- (c) reducing performance variations attributable to process variations, temperature changes and/or supply voltage variations;
- (d) mimicking bipolar device operation within the digital to-analog converter with bipolar devices in the beta compensation module to compensate for beta current loss in the digital-to-analog converter;
- and
- (e) outputting a converted analog signal based on the received digital code word.
Dependencies are inferred from the claim text.