Handset RF power amplifier characterisation system

27 February 2012

Tim Haynes, CEO of Nujira

New test system enables development of optimised Envelope Tracking PAs for smartphones and other mobile devices.

Nujira has launched a new handset RF power amplifier (PA) characterisation system, the NCT-T9102, targeted at OEMs, chipset suppliers and PA vendors wishing to measure the performance of Envelope Tracking RF PAs for low power applications.

The company has developed this system specifically for characterising handset RF PAs under Envelope Tracking (ET) conditions, overcoming the huge challenge of characterising PAs in ET mode using standard test equipment. Nujira will be demonstrating its new characterisation system to potential customers at Mobile World Congress in Barcelona, Spain, taking place from 27 February - 1 March.

Already in use by several major PA vendors and OEMs worldwide, the NCT-T9102 test system can be used to characterise existing PAs and also to develop future ET-optimised PA devices. OEMs and platform chipset vendors wishing to compare and contrast ET PAs from different vendors can also benefit from the capabilities of the characterisation system.

Tim Haynes, CEO of Nujira (pictured) commented: “Nujira is working with the world’s leading suppliers of RF Power Amplifiers to enable them to develop and bring to market high performance handset PAs which take full advantage of the system benefits offered by Envelope Tracking. Providing our partners with this dedicated test equipment is a critical step in our roadmap to enable an industry-wide ET ecosystem for PA vendors and handset OEMs.”

The NCT-T9102 system features a high bandwidth, low impedance dynamic supply modulator with a power supply bandwidth in excess of 60 MHz, incorporating accurate measurement of dynamic PA efficiency. The supplied software provides real time displays of the AM/AM and AM/PM distortions in the amplifier as well as the resultant spectrum and efficiency profile. The hardware includes an IQ modulated transmitter and two complex receivers, covering the 650-2700 MHz frequency range. The system includes a selection of predefined WCDMA and LTE waveforms, as defined by the OpenET Alliance, and enables development of the shaping table function which maps RF level to PA supply voltage.

Accurately measuring the efficiency of an Envelope Tracking PA under dynamic supply modulation is one of the most challenging tasks faced by developers of RF Power Amplifiers. It requires generation of precisely time-aligned envelope and RF signals; a high bandwidth, high current, low impedance power supply modulator; high bandwidth sensing of instantaneous current and voltage supplied to the PA; and measurement of the instantaneous RF power at input and output of the PA. All of this data must be captured at more than 100 million samples/second, and then correlated to calculate the instantaneous efficiency of the RF PA.

Gerard Wimpenny, CTO of Nujira added: “This combination of dynamic efficiency measurement with instantaneous phase measurement capability puts our characterisation system well ahead of any other PA test equipment on the market.”

The NCT-T9102 also includes comprehensive automation support. A well-documented software API enables customers to develop highly automated lab setups using external scripting languages such as LabVIEW, VEE, C# or MATLAB. This means that customers are able to combine the NCT-T9102 with other standard lab equipment, and make repeatable measurements, enabling accurate characterisation of PAs across frequency, temperature, and load impedance with standard or user-defined waveforms and shaping tables.


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