Category:Emitter degenerated current mirrors

The use of emitter resistors is commonly used to linearize the gain response of single-stage amplifiers. It is also employed in the design of current mirrors as an effective way to increase the output resistance by way of introducing negative feedback aimed to maintain the bias current constant over load voltage variations. The price paid here is the reduced headroom needed to accommodate the emitter resistor which results in a larger (worse) compliance voltage.

The emitter degenerated current mirror topology is a variation of the Widlar current source originally employed to allow the generation of low bias currents while circumventing the use of large integrated resistors (which otherwise consume significant layout area).