A 2.5-V Low-Reference-Voltage, 2.8-V Low-Collector-Voltage Operation, HBT Power Amplifier for 0.8-0.9-GHz Broadband CDMA Applications

This paper describes circuit design and measurement results of a pure HBT MMIC power amplifier module (PA) operating with a 2.5-V low reference (V_ref) and 2.8-V low collector supply voltages (V_cc). While covering 824-925-MHz broadband CDMA operation at 2.8-V V_cc, the PA allows a 1.1-V low V_cc and 18-dBm Pout operation. This is realized by an on-chip step quiescent current selector monitoring collector voltage. Measurement results under the 2.8/1.1-V V_cc and 2.5-V V_ref bias conditions show that the PA meets J-/W-CDMA power and distortion specifications sufficiently over a wide temperature range from -20 to 85degC while operating over a wideband from 824 to 925 MHz. For J-CDMA (IS-95B) modulation, the PA can deliver a 28-dBm P_out, a 36% PAE, and a -50-dBc ACPR, while a 29-dBm P_out, a 38% PAE, and a -40-dBc ACLR are achieved for W-CDMA (R99) modulation. In addition, the PA is capable of delivering a 18-dBm P01lt and more than 23% PAE under 824-925-MHz and 1.1-V J-CDMA modulation test conditions. To the best of author´s knowledge, this is the first report on a broadband CDMA PA operating with low V_ref and low V_cc.