Stromspiegel mit wenigstens einem pnp-Transistor

摘要

A current mirror with at least one pnp-transistor (10, 11) has an emitter (14, 15) to which is applied a positive voltage. Both collectors are designed as partial collectors (16, 17 or 18, 19) of a collector that surrounds the emitter (14, 15) substantially as a ring. The first partial collector (16, 18) and the base (20) are connected to a source of reference current (21) and the second partial collector (17, 19) is linked to a connection (22) of the current source that needs to be protected against overvoltage. In the case of an overvoltage at the connection (22), the emitter is formed by the second partial collector (17, 19) linked to said connection (22). In case of overvoltage, therefore, the absorbed current can rise only up to a limit value (Iü) which is in a topology-conditioned relation to the reference current (Iref) of the mirror. An effective protection against overvoltages is thus ensured.