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LTC6947 - Ultralow Noise 0.35GHz to 6GHz Fractional-N Synthesizer

The LTC®6947 is a high performance, low noise, 6GHz phase-locked loop (PLL), including a reference divider, phase-frequency detector (PFD), ultralow noise charge pump, fractional feedback divider, and VCO output divider.

The fractional divider uses an advanced, 4th order ΔΣ modulator which provides exceptionally low spurious levels. This allows wide loop bandwidths, producing extremely low integrated phase noise values.

The programmable VCO output divider, with a range of 1 through 6, extends the output frequency range. The differential, low-noise output buffer has user-programmable output power ranging from –4.3dBm to +4.5dBm, and may be muted through either a digital input pin or software.

The ultralow noise charge pump contains selectable high and low voltage clamps useful for VCO monitoring, and also may be set to provide a V+/2 bias.

All device settings are controlled through a SPI-compatible serial port.

Features Low Noise Fractional-N PLL No ΔΣ Modulator Spurs 18-Bit Fractional Denominator 350MHz to 6GHz VCO Input Range –226dBc/Hz Normalized In-Band Phase Noise Floor –274dBc/Hz Normalized In-Band 1/f Noise –157dBc/Hz Wideband Output Phase Noise Floor Excellent Integer Boundary Spurious Performance Output Divider (1 to 6, 50% Duty Cycle) Output Buffer Muting Charge Pump Supply from 3.15V to 5.25V Charge Pump Current from 1mA to 11.2mA Reference Input Frequency Up to 425MHz Fast Frequency Switching FracNWizard™ Software Design Tool Support Typical Application

Applications Wireless Basestations (LTE, WiMAX, W-CDMA, PCS) Broadband Wireless Access Microwave Data Links Military and Secure Radio Test and Measurement Packaging

Demo Boards