Xilinx, Inc.
Embedded variable gain amplifier in a current steering digital-to-analog converter

Abstract:

Apparatus and associated methods relating to a digital-to-analog converter (DAC) include a programmable resistance network coupled between a voltage supply node V.sub.DD and a switch cell circuit to provide a predetermined resistance in response to the V.sub.DD and current I.sub.S of the switch cell circuit. In an illustrative example, the DAC may include a switch cell circuit comprising one or more switch cells connected in parallel. Each switch cell may include a differential gain circuit having a first branch coupled to a second branch at an input of a current source. The programmable resistance may include a variable resistance configured to adjust a voltage (Vbias) supplied to the switch cell circuit in response to a control signal. By introducing the programmable resistance network, predetermined bias and/or gain values may be dynamically adjusted with a constant board-level power supply V.sub.DD.