2GHz to 14GHz mixer with LO frequency doubler achieves low IIP3

August 10, 2015 // By Graham Prophet
LTC5549 is a double-balanced mixer that can operate either as an upconverter or downconverter, with a wide RF frequency range from 2 GHz to 14 GHz. It has high linearity of 24.4 dBm IIP3 at 9 GHz.

LTC5549 enables efficient microwave transmitter and receiver designs with an integrated LO buffer that needs only a 0-dBm drive level, effectively eliminating an external high power LO amplifier circuit. It has an integrated on-chip, switchable frequency doubler for LO signal, providing an option to use lower cost, commonly available low frequency synthesisers. The LTC5549 employs wideband integrated balun transformer optimised to extend RF frequency bandwidth from 2 GHz to 14 GHz while enabling single-ended operation. Its IF port also has wide bandwidth up to 6 GHz. All three ports are 50-Ω matched. The mixer offers high port-to-port isolation, minimising undesireable LO leakage, and easing external filtering requirements. Conversion loss is specified as 8.0 dB.

The device’s performance matches a range of microwave applications including microwave backhaul, high unlicensed band LTE-Advanced base stations, satellite broadband radios, radar systems, X-band and Ku band transceivers, test equipment and satellite modems.

It has improved ESD protection with 2,000V ESD human body model (HBM) rating on all pins. The device is available in a 12-lead, 3 x 2 mm plastic QFN package. With its minimal external component design, the LTC5549 results in a compact solution footprint. The device is rated for operation from –40°C to 105°C case temperature to support extended environmental operating temperature. The mixer is optimised for single 3.3V supply operation, drawing a nominal supply current of 115 mA, and has an enable/disable pin. When deactivated, the device draws 100 μA maximum standby current. The enable pin can be driven directly to turn the device on and off rapidly in less than 0.2 μsec, supporting time-division duplex (TDD) or burst mode type radios. The LTC5549 is priced starting at $10.07 (1,000).

Linear Technology; www.linear.com/product/LTC5549