The LMX2604 is a fully integrated VCO (Voltage-Controlled Oscillator) IC designed for GSM900/DCS1800/PCS1900 triple-band application. The IC is ideal for use in the transmitter modulation loop by providing extremely small form factor and low phase noise. The IC has two VCOs, one for GSM and a second for DCS/PCS. The IC has two separate buffer amplifiers to drive an external high power amplifier, one for GSM900 band and the other one for DCS1800/ PCS1900 bands. The IC also has a differential buffer amplifier to drive a mixer for the offset PLL.