OPTIMIZATION OF A MINATURE TRANSMITTER MODULE FOR WIRELESS TELEMETRY APPLICATIONS

Abstract

M/A-COM, Inc. has previously developed a highly integrated transmitter chip set for wireless telemetry applications for the military L and S band frequencies and the commercial 2.4GHz ISM band. The original chip set is comprised of a voltage controlled oscillator (VCO), a silicon phase locked loop (PLL), and a family of power amplifiers (PA's). Using these components, M/A-COM has produced a miniature IRIG-compliant transmitter module, which has been flight-tested by the U.S. Army’s Hardened Subminiature Telemetry and Sensor System (HSTSS) program. Since the initial offering, several product enhancements have been added. The module performance has been improved by tailoring the VCO specifically for direct frequency modulation applications. In addition to improving noise performance, these enhancements have produced improved modulation linearity, decreased lock time and increased carrier stability. Modulation rates in excess of 10Mbps have been demonstrated. High efficiency power amplifiers operating at 3V have also been added to the family of amplifiers (PAE > 50%). This greatly enhanced efficiency allows higher RF power output while maintaining the same miniature form factor for the transmitter. Further, M/A-COM has added a silicon-on-sapphire PLL to the chip set, which operates at frequencies up to 3.0GHz. This paper details the enhancements to the components within the chip set, and the improvement in performance of the transmitter module. Test data is presented for the transmitter modules and individual components.