Canceling feedback resistor loading effect in a shunt-shunt feedback circuit

摘要

A shunt-shunt feedback current to voltage converter (60) including a compensating current (22) provided to the output of the amplifier (12) which mirrors the input current (14) advantageously removing the loading effects of the feedback resistor (Rf) to the amplifier (12). A current steering DAC (40) is utilized in conjunction with a plurality of polarity control switches (62) to provide either a source current or a sink current to the amplifier input, and a complementary sink current or source current, respectively, to the output of the amplifier such that the amplifier (12) does not provide any current to the feedback resistor. Thus, DC gain of the amplifier is maintained. The current steering DAC (40) provides a matched source current and sink current to achieve this architecture.