Patent ID: 7233274

Claim:
An apparatus that includes facility for level shifting an input signal, comprising: an AC coupling circuit that is coupled between a first node and a second node, wherein the first node is arranged to receive the input signal, and wherein the AC coupling circuit is arranged to AC couple the input signal to the second node; an analog processing block that includes an input terminal that is coupled to the second node, wherein the input terminal of the analog processing block comprises a gate of a field effect transistor; a digitally programmed voltage reference circuit that is arranged to provide a reference signal to a third node in response to a digital control signal, wherein the digitally programmed voltage reference circuit comprises an analog reference voltage generator circuit that is coupled to a voltage divider circuit that includes a set of tap-points, wherein each of the set of tap-points in the voltage divider circuit are coupled to a respective input of a multiplexer circuit, wherein one of the set of tap points is selectively coupled to the third node in response to the digital control signal; and a high impedance DC coupling circuit that is coupled between the second node and the third node such that a DC level associated with the second node is adjusted by the digitally programmed voltage reference circuit such that the input terminal of the analog processing block has a precisely adjusted DC level.