A 2.5-V Low-Reference-Voltage 2.8-V Low- Collector–Voltage Operation 0.8–0.9-GHz Broadband CDMA BiFET Power Amplifier With an Input SPDT Band Select Switch

This paper describes circuit design and measurement results of a bipolar field-effect transistor monolithic microwave integrated circuit power amplifier (PA) module operating with a 2.5-V low reference voltage (V_ref) and a 2.8-V low collector supply voltage (V_cc). While covering 824-925-MHz broadband CDMA operation at 2.8 V of V_cc, the PA allows a 1.1-V low V_cc and 18-dBm output power (P_out) operation. This is realized using an on-chip step quiescent current control scheme depending on V_cc. In addition, an input high electron-mobility transistor single-pole double-throw switch is integrated on the PA die for selecting 800/900-MHz operating bands, thereby providing easy connectivity between a transmit surface acoustic wave filter and the PA. 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-CDMA/W-CDMA power and distortion specifications sufficiently over a wide temperature range from -20 °C to 85 °C while realizing a broadband operation ranging from 824 to 925 MHz. For J-CDMA (IS-95B) modulation, the PA can deliver a 28-dBm P_out, a 36% power-added efficiency (PAE), and a - 50-dBc adjacent channel power ratio, while a 29-dBm P_out, a 38% PAE, and a -40-dBc adjacent channel leakage power ratio (ACLR) are achieved for W-CDMA (3GPP R99) modulation. Under 3:1 load mismatching condition, the PA also suppresses ACLR of less than - 36 dBc while keeping a forward power of 27.5 dBm. Moreover the PA is capable of delivering a 18-dBm P_out and more than 26% PAE under 824-925-MHz and 1.1-V J-CDMA modulation test conditions. To the best of authors´ knowledge, this is the first report on a broadband production-level CDMA PA operating with low V_ref and low V_cc.