Linear differential voltage-current converter

The use of two complementary emitter-followers, in which the collector currents are held effectively constant by feedback action, facilitates the design of a differential voltage- current converter capable of producing lower output signal distortion. The proposed circuit provides an extended linear operating range, and total harmonic distortion (THD) 20 dB better than that compared with an emitter-degenerated long- tailed pair circuit. Simulation results show that the THD is better than -70 dB for differential input signals up to 0.5 V at a test frequency of 1 MHz and supply voltage of plusmn5 V.