A low-power baseband receiver IC for frequency-hopped spread spectrum communications

A baseband receiver IC which will be incorporated into a low-power frequency-hopped spread spectrum (FH/SS) transceiver for 902-928 MHz ISM band applications is presented, The chip performs noncoherent binary/quaternary frequency shift keying (FSK) demodulation, equal-gain diversity combining of dual antenna branches, and symbol and frequency synchronization. The chip also accommodates variable data rates from 2 to 160 kb/s, programmable hop rates, and tunable bandwidth loop filters, The core area of the 1-mu m CMOS chip is 3.9 mm x 3.9 mm with a power consumption of 4.5 mW at 10 MHz from a 3-V supply. A baseband transceiver system utilizing this receiver chip for the prototype handset to demonstrate a point-to-point communication link is also described, Two XILINX FPGA chips were used to implement the remainder of the baseband transceiver functions, including frequency control logic for FSK modulation, acquisition control, data framing, symbol interleaving and deinterleaving, and interface control for data and voice.