Low Noise Cellular Receiver Amplifiers

Low noise and high dynamic range are the keys to success for cellular base station receiver front-end amplifiers. Lower noise means slightly longer range and high dynamic range translates to less intermodulation interference from strong adjacent-channel signals.

Three new low noise receiver amplifiers have been added to the Pure-AMPs™ product line. The models MPS-0808A9-85, MPS-0809A9-85 and MPS-0909A9-85 amplifiers cover the base station frequency ranges of 806 to 849 MHz, 870 to 925 MHz and 940 to 956 MHz, respectively. The amplifiers are built with the company’s Pure-FETs™ devices and exhibit an exceptionally low 1.1 dB noise figure while maintaining a high +36 dBm third-order intercept point. Gain is 16 dB (typ), with +22 dBm of output power at the 1 dB compression point. The devices used in the amplifiers exhibit high spectral purity and high efficiency as a result of proprietary vapor phase epitaxial processes and quarter-micron recessed-gate technology.

Each of the low noise, high dynamic range amplifiers has been optimized for a particular cellular frequency band. The MPS-0808A9-85 amplifier is designed for 806 to 849 MHz cellular system use. The MPS-0809A9-85 amplifier is targeted for 900 MHz Global System for Mobile communications, Nordic Mobile Telephone (NMT-900) system and Extended Total Access Communications System applications. The MPS-0909A9-85 amplifier is optimized for the personal digital cellular system.

Each amplifier type incorporates a single GaAs FET with internal matching designed for 6 V DC operation at 180 mA (typ) drain current and a power-added efficiency of 26 percent. The devices exhibit an input/output SWR of 2.0 (typ) and 2.5 (max). Maximum RF input power is specified at +200 mW continuous. Each amplifier type has a ±0.2 dB typical gain variation with frequency and a –0.015 dB/°C gain variation with temperature. Figure 1 shows the model MPS-0809A9-85 amplifier’s typical 25°C gain and input/output return losses at Vdd = 6 V and Idd = 212 mA.

The amplifiers are housed in a small half-flange drop-in package measuring 0.25" x 0.47", as shown in Figure 2 . The devices are designed for +85°C maximum case operating temperature, and are suitable for low noise, high dynamic range receiver applications such as tower-mounted low noise amplifiers, cellular base station receivers, bidirectional amplifiers and smart antenna systems.

MicroWave Technology Inc. (MwT), Fremont, CA (510) 651-6700.