Microwave Journal

Low Noise Cellular Receiver Amplifiers

Three new amplifiers suitable for low noise, high dynamic range receiver applications

July 1, 1997

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.