A differential switched-capacitor amplifier with programmable gain and output offset voltage

The design of a low-power differential switched-capacitor amplifier for processing a fully-differential input signal coming from a pressure sensor interface is reported. The circuit is intended to amplify the input signal, convert it to single-ended mode and shift its output by an offset voltage. The gain and output offset voltage are digitally programmable. The differential switched-capacitor amplifier employs an op amp voltage cancellation technique without requiring its output to slew to analog ground each time the amplifier is reset. Additionally, the circuit topology is very insensitive to low op amp gain and allows to attain 9-bit linearity. Moreover, a switched-capacitor commonmode feedback configuration with symmetric loading of the differential mode loop has been adopted to reduce charge injection and leakage current errors as well as to settle much faster than traditional CMFB circuits. The circuit has been successfully integrated into a SoC device where, after the analog pr...

• Type: Conference
• Year: 2006
• Where: SBCCI
• Authors: Fabio Lacerda, Stefano Pietri, Alfredo Olmos
• Keywords: Input Signal, OP AMP, Output Offset Voltage, SBCCI 2006