5G needs more bandwidth: LTC5553 mixer helps designers find it

-May 23, 2017

Faster backhaul and fronthaul (basestation) links are critical to making 5G a reality. In the movie “Short Circuit,” the robot, designated as ‘Number 5’ (did they see 5G coming?) pleads for “More input!” when he demands to access more data as fast as he can. In 5G, communication systems are saying “More bandwidth, designers!”

Linear Technology, now part of Analog Devices, has introduced their LTC5553, a 3GHz to 20GHz, double balanced mixer with integrated LO buffer. The mixer can be used in either an up- or downconverter with a linearity of 23.9dBm IIP3 at 14GHz, and 21.5dBm at 17GHz.

The integrated LO buffer needs only 0dBm input drive, which eliminates the need of an external high power LO amplifier circuit. By integrating the wideband LO buffer amplifier in the IC, it enables less external components, simplifies design, and enhances performance. Not only does it save costs, it also eliminates having a +10dBm to +17dBm power signal in the system. At frequencies 10’s of GHz, such a high power signal is potentially a major source of LO radiation that can couple to the RF or the IF ports, as well as other sensitive radio circuits. This would necessitate more external filters to keep signal corruptions under control, as well as extra shielding hardware that may be necessary to contain the radiation.

It also has integrated wideband balun transformers on chip. This enables all ports to operate single-ended, and 50Ω matched over their respective specified frequency range.



The mixers port-to-port isolation gives the necessary low –32dBm LO to RF leakage at 17GHz, which simplifies external filtering requirements.



The mixer’s added features result in minimum external components, simplified design, and a very small solution size in a tiny 12-lead, 3×2mm plastic QFN package.

Applications

The mixer’s very wide bandwidth and excellent performance is perfect for a wide range of applications including 5G microwave backhaul, broadband wireless services, satellite broadband radios, radar systems, active antenna arrays, X and Ku band transceivers, test equipment, spectrum analysis and satellite communications.

Temperature range

The device is rated for operation from –40°C to 105°C case temperature to support extended environmental operating temperature.

Power supply requirements

The mixer is powered from a single 3.3V supply, drawing a quiescent supply current of 132mA. Additionally, it can be shut down via an enable pin. When deactivated, the device draws only 100μA maximum standby current. The enable pin can be driven directly to turn the device on and off rapidly in less than 0.2μs, supporting time-division duplex (TDD) or burst mode type transmitters and receivers.

Pricing

The LTC5553 is priced starting at $22.00 each in 1,000-piece quantities.

For more information, visit the Linear Technology website.

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