R&S SMW200A Generates RF And Envelope Signals In Realtime To Test Envelope Tracking Performance Of Power Amplifiers

A major portion of amplifier power in smartphones dissipates as heat. The envelope tracking (ET) technique makes it possible to significantly enhance amplifier efficiency as it allows the amplifier supply voltage to track the envelope of the RF signal. Rohde & Schwarz offers a new option to test power amplifier ET performance. The R&S SMW200A high-end vector signal generator can now deliver RF and envelope signals in a single instrument.

Rohde & Schwarz has enhanced its new R&S SMW200A high-end vector signal generator by adding the R&S SMW-K540 option for envelope tracking. This option enables quick and easy testing of envelope tracking power amplifiers for smartphones, base stations and tactical radios.

Because of the specific power distribution of RF signals with modern communications standards such as LTE and WCDMA, power amplifiers generally exhibit poor efficiency since spare capacity has to be reserved for high crest factors. With envelope tracking, the amplifier supply voltage is controlled in such a way that it tracks the envelope of the RF signal. As a result, the amplifier always operates in a range close to its instantaneous maximum output power, considerably boosting amplifier efficiency. Using shaping functions, the amplifier can be optimized for linearity or efficiency.

Rohde & Schwarz meets the test requirements of chipset manufacturers by offering a solution that generates fully synchronous RF and envelope waveforms in a single instrument. Users can delay the RF waveform and the envelope waveform relative to each other by ±500 ns with 1 ps resolution. Due to its outstanding performance characteristics, the R&S SMW200A delivers an extremely low-noise envelope signal at the analog baseband outputs. The signal generator calculates the envelope waveform from the baseband signals in realtime, so that all communications standards supported by the R&S SMW200A as well as custom waveforms can be used. A large selection of flexible shaping functions allows users to optimize the envelope in realtime.

The envelope tracking parameters can be configured on the generator’s straightforward graphical user interface. Automatic envelope voltage adaptation is available to speed up setup and testing time since the main parameters such as VCC voltage range, PAin range, DC modulator gain, DC offset and power offset only need to be entered once. Automatic recalculation of the envelope based on the power amplifier input level makes it possible to perform power sweeps over the amplifier’s entire input range.

The new R&S SMW-K540 software option for envelope tracking is now available from Rohde & Schwarz. Rohde & Schwarz will present the test solution at the European Microwave Week in Nuremberg in hall 7A, booth 106.

About Rohde & Schwarz
Rohde & Schwarz is an independent group of companies specializing in electronics. It is a leading supplier of solutions in the fields of test and measurement, broadcasting, radiomonitoring and radiolocation as well as secure communications. Established almost 80 years ago, Rohde & Schwarz has a global presence and a dedicated service network in over 70 countries. It has approx. 8700 employees and achieved a net revenue of € 1.8B (USD 2.3 billion) in fiscal year 2011/2012 (July 2011 to June 2012). Company headquarters are in Munich, Germany.