Out in Front: August 15, 1996

A silicon, monolithic-microwave IC comprises most of the RF circuitry for OEM Global Positioning System (GPS)-receiver designs. The UPB1004GS from NEC (Mountain View, CA) includes a double-conversion down-converter and PLL frequency synthesizer in a

30-lead SSOP package. A single internal oscillator serves both down-converter functions in the 3V/38-mA IC. The IC's outputs go to the GPS receiver DSP for further decoding and processing.

The device takes a 1575.42-MHz GPS L1-band spread-spectrum signal after it has passed through a low-noise preamplifier. The first IF frequency is 61.38 MHz, which results from mixing with the 1636.8-MHz, onboard local oscillator. This oscillator also produces a second local-oscillator frequency of 65.472 for use during the second down-conversion stage. The second IF output frequency ranges as high as 5 MHz, with a 40-dB conversion gain. An additional IF amplifier stage yields another 40-dB gain; total conversion gain is typically 92.5 dB. In addition, the device has an internal AGC loop with 20 dB of control range. The UPB1004GS costs less than $5 (100,000); an evaluation board is available to OEM designers. The products are available from California Eastern Laboratories, the exclusive US agent/distributor for NEC RF products.

—by Bill Schweber

California Eastern Laboratories, Santa Clara, CA. (408) 988-3500, fax (408) 988-0279. Circle No. 482