DESCRIPTION
The LTC®1340 is a varactor diode driver designed to generate 5V varactor drive from a single 3V or higher voltage supply. It includes a low noise amplifier with an internal gain of 2.3 and a self-contained charge pump to generate output voltages above the input supply. The amplifier input stage includes a built-in offset voltage that allows the output voltage to swing to ground without requiring OV on the input. This feature maintains the phase detector within its linear range of operation. The LTC1340 requires only three external surface mount capacitors to implement a complete varactor driver module.

FEATURES
■ Generates 5V Varactor Drive from a 3V Supply
■ Wide Supply Voltage Range: 2.7V to 6V
■ Requires Only Three External Components
■ Micropower Operation: 400µA at 3V Supply
■ Shutdown Mode Drops Supply Current Below 1µA
■ Low Output Noise: 15µVRMS
■ Amplifier Gain: 2.3
■ Up to 500kHz Signal Bandwidth
■ MS8 and SO-8 Packages
■ Very Low Input Bias Current: 10nA Max
■ Amplifier Offset Maintains Phase Detector in Linear Region

APPLICATIONS
■ 5V Varactor Drive from a Single Li-Ion Cell
■ 5V Varactor Drive from Three NiCd/NiMH Cells
■ Cellular Telephones
■ Portable RF Equipment
■ Radio Modems
■ Wireless Data Transmission