A fully integrated transceiver chip for the 900 MHz communication bands

A low-cost fully integrated transceiver chip has been developed for the 900-MHz communication band. The monolithic microwave integrated circuit (MMIC) chip is packaged in a 24-pin surface mount plastic package for cost reduction. The transmitter has 25-dB gain and upconverts a 90-MHz intermediate frequency signal to 914 MHz at a power level of 15 dBm. The receiver, which shares the local oscillator (LO), has 15-dB gain and downconverts a 959-MHz RF signal to 45 MHz. The SSB receiver noise figure is 6 dB. LO frequency is set by an off-chip high-Q coaxial resonator with a measured phase noise of -95 dBc/Hz at 10-kHz offset. DC current consumptions are 60 mA in the full duplex mode and 20 mA in the receive-only mode using a 3.6-V supply. The MMIC chip was tested in a prototype 40-channel FM cordless phone that operated off a 3.6-V battery. Results demonstrated good audio quality within a 50-m line-of-sight range.<>