Patent ID: 8680914

Claim:
A controlled current source comprising: a signal input to receive a control input bus signal; a mapping unit with an input coupled to the signal input and an output to provide an internal control bus signal; a reference generator with an input coupled to the output of the mapping unit and with a low reference output to provide a low reference potential and with a high reference output to provide a high reference potential; a current generating unit with a first input coupled to the output of the mapping unit, a second input coupled to the output of the reference generator and an output to provide an output current controlled by the control input bus signal and the low and high reference potentials, wherein the control input bus signal comprises a binary coded digital signal with n bits (D0, . . . , D[n−1]), and wherein a first subset of output current levels ranging from zero to 2 n−1 −1is provided using the low reference potential and a second subset of output current levels ranging from 2 n−1 to 2 n is provided using the low and high reference potentials.