A 3-V monolithic SiGeHBT power amplifier for dual-mode (CDMA/AMPS) cellular handset applications

A dual-mode (CDMA/AMPS) power amplifier has been successfully implemented b y using a monolithic SiGe/Si heterojunction bipolar transistor (HBT) foundr y process for cellular handset (824-849 MHz) applications. The designed two -stage power amplifier satisfies both CDMA and AMPS requirements in output power, linearity, and efficiency. At V-cc = 3 V, the power amplifier shows an excellent linearity (first ACPR < -44.1 dBc and second ACPR < -57.1 dBc) up to 28 dBm of output power for CDMA applications. Under the same bias co ndition, the power amplifier also meets AMPS handset requirements in output power (up to 31 dBm) and linearity (with second and third harmonic to fund amental ratios lower than -37 dBc and -55 dBc, respectively). At the maximu m output power level, the worst power-added efficiencies (PAEs) are measure d to be 36% for CDMA and 49% for AMPS operations. The power amplifier also tolerates severe output mismatch (VSWR >12:1) up to V-cc = 4 V, with spurs measured to be < -22 dBc in CDMA outputs at two specific tuning angles, but with no spur in AMPS outputs at any tuning angle.