Linear Technology announces the LTC6945, a 6GHz integer-N frequency synthesizer with -226dBc/Hz normalized closed-loop in-band phase noise, -274dBc/Hz normalized in-band 1/f noise, a wideband phase noise floor of -157dBc/Hz and -102dBc spurious output. In a typical 900MHz application, these performance attributes enable a closed-loop phase noise of -100dBc/Hz at 1kHz offset. The LTC6945 is designed to work in conjunction with an external low noise VCO up to 6GHz. In addition, the device has an on-chip output divider that is programmable from 1 through 6 to extend the tuning frequency coverage to as low as 350MHz.

The LTC6945 comprises a low noise reference buffer, a reference divider, phase-frequency detector (PFD) with phase-locked indicator, an ultralow noise programmable charge pump and an integer feedback divider to attain very low noise PLL operation. The on-chip SPI-compatible bidirectional serial port allows frequency tuning and control, and read back of the register and loop status information.

The PLLWizard comprehensive PC-based design tool software is available to facilitate interactive control and to interface with the LTC6945’s evaluation board. Designers can perform simulations and optimization with the PLLWizard software, and then interactively verify their designs on the actual demonstration circuit. The PLLWizard design tool is available for download free of charge at www.linear.com/PLLWizard.

The LTC6945 is specified over the full case temperature range from -40°C to 105°C. The LTC6945 is now available from stock in a 4mm x 5mm, 28-lead plastic QFN package.