Current characteristic shaper

First (Q1) and second (Q5) transistor current sources of complementary conductivity types are connected in series with an output connection (21) between them in the series connection. Input signals control the conduction level of one of the sources so that it diverts correspondingly variable amounts of current of the other source away from the output connection in accordance with a first linear characteristic. Additional transistor current source circuits (Q2, Q6) are provided, and responsive to a predetermined level of the same input signals, for diverting substantially different amounts of current away from the output connection in accordance with a second linear characteristic of different slope from the first characteristic.