Phoenix, Arizona–Motorola’s Semiconductor Products Sector has completed qualification of its true enhancement-mode heterostructure field effect transistor wafer process. The single-power supply gallium arsenide (GaAS) process was engineered, the company reports, to provide exceptional and cost-effective performance in both linear transmitter and receiver circuits for low-voltage portable wireless applications.

“Motorola’s advanced enhancement-mode GaAs technology provides advantages over depletion-mode pseudomorphic high electron mobility transfer (pHEMT) devices,” says Karl Johnson, director of Motorola’s Compound Semiconductor Technologies Laboratory. “Because of its low off-state leakage current, this true enhancement-mode device eliminates the drain-supply switch required for depletion-mode pHEMT and metal semiconductor field effect transistor (MESFET) devices.”

A 3-stage power amplifier designed for a 1900 MHz TDMA application has delivered output power greater than 30 dBm, 42% power-added efficiency, adjacent channel power of -30 dBc, and alternate adjacent channel power of -48 dBc. The technology is ideal for use in transmitter and receiver circuits, according to the company, for both analog and digitally modulated portable products.

“Single-supply power amplifiers have become the new paradigm in portable phone handsets due to the recent availability of near-zero threshold voltage pHEMT and heterojunction bipolar transistor technologies,” explains Jim Oakland, manager of design and technology of Motorola’s Wireless Transmitter Solutions Division. “The need for decreasing product cost and size is also a high priority. The enhancement-mode GaAs technology helps to reduce the cost and size of the end product by eliminating both the negative voltage generator and the drain supply-switch within the handset power amplifier section, as well as eliminating additional passive components.”

Products using this technology are expected to be available early next year.