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28 May 2013

Freescale unveils RF control circuit enabling real-time digital adjustment of phase and amplitude for Doherty amplifiers

Freescale Semiconductor of Austin, TX, USA, which provides RF power technology for cellular markets, has launched a gallium arsenide (GaAs) monolithic microwave integrated circuit (MMIC) control circuit specifically designed to optimize the performance of its Airfast Doherty amplifiers.

The MMDS20254H advanced Doherty alignment module (ADAM) enables more accurate alignment of phase and amplitude on the carrier and peaking paths of high-power Doherty amplifiers, improving overall base-station performance. The sophisticated technology also helps enhance power efficiency while boosting performance across the entire cellular frequency band.

“The process of optimizing Doherty amplifiers can be challenging, time consuming and labor intensive,” says Ritu Favre, senior VP & general manager of Freescale’s RF business. “The MMDS20254H solution delivers the advanced technology and comprehensive support required to help RF engineers optimize the performance of Freescale’s industry-leading Airfast RF power portfolio.”

Fueled by the widespread adoption of TD-LTE and W-CDMA, Doherty amplifiers have regained prominence as an industry standard, providing high power-added efficiency (PAE) when amplifying the types of signals associated with these protocols. The MMDS20254H ADAM device offers what is claimed to be exceptional linearity/efficiency tradeoffs, while improving output power. It includes a coupler, digitally selectable phase shifters and step attenuators, while operating from a single voltage supply. The device is suitable for transmit protocols such as W-CDMA and LTE, using frequencies from 1800 to 2200MHz, and is controlled using a SPI interface.

Based on E-pHEMT and InGaP HBT technology and housed in a RoHS-compliant industry-standard 6mm QFN package, the MMDS20254H allows phase and peaking adjustments from 1800 to 2200MHz.

The device has a constant 90 degree phase offset between port 2 and port 3 versus frequency (500MHz bandwidth). Digital adjustment is possible to optimize power amplifier performance under different conditions, including power level, supply voltage and temperature.

A comprehensive evaluation kit (including the ADAM evaluation board, SPI connector board, control software and quick start guide) is available upon request to qualified customers.

See related items:

Freescale launches GaAs MMIC to boost performance of small-cell to macro-cell base stations

Tags: Freescale GaAs MMIC Doherty amplifier


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