High-frequency linear tunable single-ended voltage to differential current converter

A single-ended to differential (S-D) tunable voltage-to-current converter can replace a S-D voltage-to-voltage converter or a transformer. The resulting system is simpler and has better high-frequency performance. Measurements show that for a 9 GHz bipolar process with a power supply of 0-5 V, THD<0.15% for an input voltage of 1.2 V/sub pp/, the signals are in antiphase up to 120 MHz, the tuning range of g/sub m/ is 150-750 /spl mu/S, and the signal-to-noise ratio reaches 65 dB for the bandwidth of 500 MHz.