Patent ID: 7227481
Filing Date: 2007-06-05
Classification: H03M

Abstract:
1. A multi-bit sigma-delta analog-to-digital converter (ADC) comprising: a single-ended input for receiving an analog input signal; a multi-bit feedback current digital-to-analog converter (IDAC) which is operable to generate a multi-level feedback current depending on a feedback signal; a summing node which is operable to sum the input signal with the feedback current; and an integrator which is operable to integrate the summed signal on a continuous-time basis; wherein the IDAC is selectively connectable to the summing node via a first path and a second path, the first path transmitting current from the IDAC to the summing node with a first polarity, and the second path transmitting current from the IDAC to the summing node with an inverted polarity, and wherein the IDAC comprises a set of unit IDACs which are each selectively connectable to the summing node via one of a first path and a second path, the first path transmitting current from the IDAC to the summing node with a first polarity, and the second path transmitting current from the IDAC to the summing node with an inverted polarity.