Patent ID: 7102394
Filing Date: 2006-09-05
Classification: G06F

Abstract:
1. A circuit in an integrated circuit having a first input terminal and a second input terminal to be coupled to a resistor network for selecting one of a plurality of digital states in the integrated circuit, the circuit comprising: a tri-state circuit coupled to the first and second input terminals, the tri-state circuit, in response to a tri-state control signal, operative to drive a first voltage at the first input terminal and a second voltage at a second input terminal to one of first and second power supply voltages or to cause the first and second input terminals to float electrically; a multiplexer coupled to receive the first and second input voltages and select one of the first and second input voltages as a selected output voltage in response to a multiplexer select signal; a comparator coupled to receive and compare the selected output voltage of the multiplexer and a reference voltage, the reference voltage being selected from a set of voltage levels between the first and second power supply voltages in response to a reference select signal, the set of voltage levels being associated with the plurality of digital states and being proportional to the difference between the first and second power supply voltages, the comparator providing a comparison output signal; and a control circuit generating the tri-state control signal, the multiplexer select signal and the reference select signal, the control circuit coupled to receive the comparison output signal from the comparator and to generate a selection signal for selecting one of the plurality of digital states based on the comparison output signal.