Radio frequency (RF) and microwave amplifiers provide their best performance under specific bias conditions. The quiescent current established by the bias point affects critical performance metrics such as linearity and efficiency. While some amplifiers are self biased, many devices require external biasing using multiple supplies that must be sequenced properly for safe operation.

This application note provides an overview of bias sequencing requirements and the effects of using various bias conditions. It presents an elegant solution for biasing amplifiers using active bias controller such as the HMC980, HMC980LP4E, HMC981, HMC981LP3E, HMC920LP5E, and all externally biased RF/microwave amplifiers.