A 863–870-Mhz spread-spectrum FSK transceiver design for wireless sensor

Simulation results of a 863-870-MHz frequency-hopped spread-spectrum transceiver with binary frequency shift keying (BFSK) modulation at 20 kb/s for wireless sensor applications is presented. The transmit/receive RF front end contains a BFSK modulator, an up conversion mixer, a power amplifier (PA), and an 863-870 MHz band pass filter (BPF) at the transmitter side and a low-noise amplifier with down conversion mixer to to zero IF, a low-pass channel-select filter, a limiter and a BFSK demodulator at the receiver side. The various blocks parameters of the transmit/receive RF front end like noise figure (NF), gain, 1 dB compression point (P_-1dB)and IIP3 are simulated and optimized to meet transceiver specifications. The receiver simulations show 51.1 dB conversion gain, -7 dBm IIP3, -15 dB return loss (S₁₁) and 10 dB NF. The transmitter simulations show an output ACPR (adjacent channel power ratio) of -22 dBc, 3.3 dBm P_-1dB of PA and transmitted power of 0 dBm. The transceiver simulations show an RMS frequency error of 1.45 Khz.