Application of enhancement mode FET technology for wirelesssubscriber transmit/receive circuits

Single-supply power amplifiers have become the new paradigm in portable phone handsets due to the recent availability of heterojunction bipolar transistor (HBT) and pseudo enhancement mode PHEMT technology. We have developed a true enhancement mode heterostructure insulated-gate FET device (HIGFET) which is suitable for use in both saturated and linear power amplifiers. A three-stage power amplifier designed for 1900-MHz NADC application delivered +30-dBm output power and 41.7% power-added efficiency with an adjacent channel power of -29.8 dBc and alternate adjacent channel power of -48.4 dBc. In addition to this, we have demonstrated excellent noise figure and linearity performance for small-signal applications. At 900 MHz and bias conditions V_DS=1.0 V and I_DSQ=1 mA, a single-stage amplifier achieved a noise figure of 1.17 dB with an associated gain of 18.5 dB. These results make the technology an ideal candidate for application in both transmitter and receiver circuits