The MICRF405 is a 290MHz-980MHz RF transmitter IC designed for unlicensed ISM band operations. It's designed to work in the North American 315MHz and 915MHz bands as well as the European 433MHz and 868MHz bands. The device is fully FCC Part 15.247 and EN300-220-compliant. The transmitter consists of a FSK/ASK modulator, PLL frequency synthesizer and a power amplifier. The frequency synthesizer consists of a voltagecontrolled oscillator (VCO), a crystal oscillator, dual modulus prescaler, programmable frequency dividers and a phase-detector. The loop-filter can be internal or external. The output power of the power amplifier can be programmed to eight levels. A lock detect circuit detects when the PLL is in lock. In FSK mode, the user can select between three different modulation types allowing a data rate up to 200kbps. When selecting FSK modulation applied with dividers, the MICRF405 is switching between to sets of register values (M0,N0,A0:"0" and M1,N1 and A1:"1"). The second modulation type is closed loop VCO modulation using the internal modulator that applies the modulated data to the VCO. The third FSK modulation type is Open loop VCO modulation.