Current mirror having a base current compensation circuit with a compensation mirror and a voltage clamp

摘要

A base current compensation circuit is configured for connection to a first current mirror that has lost base current. The compensation circuit includes a compensation mirror coupled in a feedback loop to the first current mirror. A current sensing transistor senses the lost base current. A current duplicating mirror is coupled to the current sensing transistor and generates a compensation current in response to the sensed lost base current. The compensation current is fed back into the first current mirror to compensate for the lost base current. A voltage clamp is coupled to the current sensing transistor and the current duplicating transistor. The voltage clamp maintains approximately equal collector- base voltages in the current sensing transistor and the current duplicating transistor to increase accuracy of the compensation mirror.