Linear Technology launches wideband SiGe mixer
Linear Technology has announced the LTC5549, a double-balanced mixer that can operate either as an upconverter or downconverter, with a wide RF frequency range from 2GHz to 14GHz. The LTC5549 is said to offer exceptionally high linearity of 24.4 dBm IIP3 at 9GHz.
Most microwave mixers are built using discrete GaAs diodes or FETs in hybrid modules. In contrast, the LTC5549 is constructed using a high frequency advanced SiGe BiCMOS process.
The highly integrated device includes an on-chip LO buffer and microwave balun transformers. The LTC5549's integrated LO input buffer needs only a 0dBm LO drive, according to the company. This effectively eliminates an external amplifier circuit, reducing costs. Also this is an advantage compared to the traditional microwave mixers that typically need an external high power LO buffer amplifier, requiring +10dBm to +17dBm power levels. The high power signal not only creates LO leakage to the RF or the IF ports, thus requires more filtering to keep it under control, but also it is an undesirable radiating source that is prone to couple to other sensitive parts of the system.
The LTC5549's performance enhances a wide 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.
The LTC5549 device is available in a 12-lead, 3mm x 2mm plastic QFN package and is rated for operation from -40degC to 105degC case temperature. The mixer is optimised for single 3.3V supply operation, drawing a nominal supply current of 115mA.
