The present invention relates to Current mirror for generating a constant mirror ratio, comprising an output transistor (Tout) having a base, an emitter and a collector, wherein a current flowing through the collector of said output transistor (Tout) constitutes an output current (Iout) of said current mirror and the collector of said output transistor (Tout) is connectable to an output circuit, a buffer transistor having a base, an emitter and a collector, wherein the emitter of the buffer transistor is connected to the base of the output transistor, a buffer current source for providing a fixed buffer current, wherein said buffer current source is connected to the collector of the buffer transistor, and a buffer base voltage control means having an input connected to the base of the output transistor and an output connected to the base of the buffer transistor, wherein the base voltage control means is adapted to controlling a voltage at the base of the buffer transistor in response to a current at the input of the buffer base voltage control means.