Patent ID: 7746959

Claim:
A system for setting a reference voltage applied to a differential receiver, comprising: a reference voltage generator operable to provide a reference voltage to be coupled to a first input of the differential receiver, the reference voltage generator comprising a digital-to-analog converter having an analog output at which the reference voltage is generated, the value of the reference voltage corresponding to a digital signal coupled to a digital input of the digital-to-analog converter; a calibration logic coupled to the reference voltage generator, the calibration logic operable to determine a range of values between a maximum reference voltage and a minimum reference voltage that allow the differential receiver to pass through a digital signal applied to a second input of the differential receiver, the calibration logic further being operable to control the operation of the reference voltage generator and to select a final value of the reference voltage from a range of values within the determined range of values; a test generator coupled to the second input of the differential receiver, the test generator operable to provide a digital test signal having predetermined characteristics to the second input of the differential receiver; a data analysis logic coupled to the calibration logic, the data analysis logic operable to analyze an output signal from the differential receiver to determine if the digital test signal is properly being coupled through the differential receiver; and a first counter incremented each time the data analysis logic has analyzed the output signal from the differential receiver at each reference voltage, the first counter operable to generate a digital count value that is coupled to the digital input of the digital-to-analog converter.