Transistor Based Source Degeneration: A Calibration-less Open-Loop Linearization Technique

Abstract

This paper introduces a source degeneration technique using a diode-connected transistor as degeneration device rather than a conventional resistor improves the robustness against changes in biasing condition and temperature, and removes the need for calibration. The method is validated using an analytical model, as well as with simulations, both at very low bias currents (where the analytic exponential model matches the behaviour of the transistor very well) as well as closer to the threshold. The method shows an improvement of 6dB to 20dB in linearity when variation of bias current and temperature of 20% are considered. Using this technique would thus enable highly linear, power efficient, open-loop amplifiers without the need for calibration systems, which have an unavoidable power and area overhead.