LTC1340

LTC1340 Low Noise, Voltage-Boosted Varactor Driver FEATURES s s s s s s s s s s s 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. The LTC1340 features output referred noise of 15µVRMS, minimizing frequency deviation in PLL frequency synthesizer systems. Supply current is 400µA typically with a 3V supply, and drops to 1µA in shutdown, maximizing operating life in battery-powered systems. Amplifier bandwidth is useradjustable from 10kHz up to 500kHz and the output typically sinks or sources 20µA, allowing fast output signal changes with a typical varactor load. The amplifier input features railto-rail input common mode range, allowing it to interface with the output of virtually any phase detector circuit. The LTC1340 is available in MS8 and SO-8 packages. 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 S...