ACPR design of power amplifier for wireless handset applications using E-mode GaAsHJFET

By using the gain expansive and compressive characteristics of two FET to compensate for the phase shift at large signal, one can greatly improve Adjacent Channel Power Ratio (ACPR) of the power amplifier. This 3 to 5 dB improvement result was verified experimentally by selecting the biasing point and the gain level of the first and second stage amplifiers. This MCM circuit-level technique is more attractive to achieve low cost and good ACPR design. As examples, some novel high efficiency power amplifiers with good ACPR for the handset applications are developed by this method. Those mass producible 0.12 cc volume (7.8 x 7.8 x 2.0 mm) multi-chip module power amplifiers (MCM PA) employ state-of-the-art enhancement GaAs HJFET devices that need only a single power supply.