A High-Transconductance Voltage-to-Current Converter Design

This paper describes the design of a high-transconductance, wide-band, temperature-insensitive bipolar differential voltage-to-current converter, the transconductance of which is determined by a chosen degeneration resistor. Detailed illustrations of current and voltage traces are included to clarify circuit operation. Comparison with previously published designs shows that this converter provides better linearity, with very low temperature sensitivity and excellent transconductance predictability. Simulation results show that the proposed circuit, with a nominal transconductance of 5 mS, has a Total Harmonic Distortion (THD) better than -70 dB at 10 MHz, with a degeneration resistor of 400 Omega over an input voltage range of 350 mV for supply voltages of +/- 2.5 V. The analysis and simulation comparisons are in good agreement.