On the simulation of low-frequency noise upconversion in InGaP/GaAs HBTs

Residual phase-noise measurements of GaAs heterojunction bipolar transistors (HBTs) with different low-frequency noise properties are used to investigate how accurate a compact HBT model can predict the upconversion of low-frequency noise under nonlinear operation. We find that the traditional low-frequency source implementation, as well as a cyclostationary noise source implementation, have shortcomings under different operation conditions. While, in general, the cyclostationary approach yields much better results, it fails under certain operation conditions. Experimental evidence is given that this is caused by overestimated correlation between baseband noise and RF noise sidebands. It is shown that a model based on cyclostationary sources with reduced cross-correlation yields good agreement between measurement and simulation in all cases.

I. Introduction

The question of how the low-frequency noise sources in semiconductor devices contribute to the noise spectrum under nonlinear operation is still a subject of intensive research. In linear operation, they cause , burst, or flicker noise with a single-pole low-pass spectrum, Lorentzian-like or shaped. In the nonlinear regime, however, this low-frequency noise is converted to high frequencies due to mixing processes. Most prominent is the contribution to the phase noise of oscillators, where the low-frequency noise dominates the spectrum close to the carrier [1].