Patent ID: 9112465
Filing Date: 2015-08-18
Classification: H03F,H03G

Abstract:
1. A circuit including a programmable gain amplifier (PGA) that generates an amplified analog output signal at a PGA output node of the PGA based on an analog input signal applied to a PGA input node of the PGA, the PGA comprising: an operational amplifier (op amp) comprising first and second op-amp input nodes and at least a first op-amp output node; an input circuit connected between the PGA input node and the first op-amp input node and configurable to selectively apply the analog input signal to the first op-amp input node; a feedback circuit connected between the first op-amp output node and the first op-amp input node and configured to apply the amplified analog output signal as a feedback signal to the first op-amp input node; and a calibration circuit connected between a calibration reference node and the first op-amp input node and configurable to selectively connect the calibration reference node directly to the first op-amp input node, wherein: for a PGA normal operating mode, (i) the input circuit is configured to connect the PGA input node to the first op-amp input node such that the analog input signal is applied to the first op-amp input node and (ii) the calibration circuit is configured to disconnect the calibration reference node from the first op-amp input node; and for a PGA calibration mode, (i) the input circuit is configured to disconnect the PGA input node from the first op-amp input node such that the analog input signal is not applied to the first op-amp input node and (ii) the calibration circuit is configured to connect the calibration reference node directly to the first op-amp input node.