The MICRF505 is a true single chip, frequency shift keying(FSK) transceiver intended for use in half-duplex, bidirectionalRF links. The multi-channeled FSK transceiver isintended for UHF radio equipment in compliance with theNorth American Federal Communications Commission (FCC)part 15.247 and 249, as well as the European TelecommunicationStandard Institute (ETSI) specification, EN300 220.The transmitter consists of a PLL frequency synthesizer anda power amplifier. The frequency synthesizer consists of avoltage-controlled oscillator (VCO), a crystal oscillator, dualmodulus prescaler, programmable frequency dividers, and aphase-detector. The loop-filter is external for flexibility andcan be a simple passive circuit. The output power of thepower amplifier can be programmed to seven levels. A lockdetectcircuit detects when the PLL is in lock. In receive mode,the PLL synthesizer generates the local oscillator (LO) signal.The N, M , and A values that give th