Tradeoff between CE and CB SiGe HBTs for Power Amplification in Terms of Frequency-Dependent Linearity and Power-Gain Characteristics

The tradeoff between common-emitter (CE) and common-base (CB) SiGe HBTs for power amplification in terms of frequency-dependent linearity and power-gain characteristics is investigated. When both CE the CB HBTs are impedance-matched for maximum output power (P
_out
), the CB configuration exhibits higher power gain, however, with higher third-order intermodulation distortion (IMD3) than that of the CE configuration at high operation frequencies. At low operation frequencies, the CE configuration can exhibit the superiority on both power gain and IMD3 characteristics. New analytical expressions for IMD3 are derived and experimentally verified for the study of the frequency-dependent linearity characteristics of different configurations