Agilent’s pure, precise signal generators help designers create next-generation wireless devices

June 13, 2012 // By Agilent Technologies
In RF communications, the seemingly insatiable demand for content continues to drive up data rates, modulation bandwidth and distortion requirements. As designers reach for new levels of performance, so must the instrumentation they use to characterize their devices.

From 9 kHz to 6 GHz, the analogue and vector versions of Agilent’s MXG and EXG X-Series signal generators (Figure 1) provide industry-leading performance in five areas: phase noise and spectral purity, bandwidth, error vector magnitude (EVM), adjacent-channel power ratio (ACPR) and output power. The MXG and EXG take that performance into new areas with advanced capabilities such as real-time baseband signal generation that supports applications in cellular communications, wireless networking, audio/video broadcasting, and navigation (e.g., GPS and GLONASS). Through these contributions, the MXG and EXG enable testing that reveals the true performance of components, receivers, power amplifiers, and other electronic devices.

Figure 1: Available in analogue and vector models, Agilent’s X-Series signal generators cover a variety of needs, from continuous-wave signals to advanced receiver testing.

Delivering wide modulation bandwidth — with accuracy

One recent example is the gigabit speed of the emerging IEEE 802.11ac wireless networking standard. It operates in the 5-GHz band and uses 256QAM modulation at bandwidths up to 160 MHz. This places a heavy burden on the signal generators used in device testing because the achievable level of modulation accuracy typically declines as signal bandwidth increases.

To meet this need, the MXG uses advanced modulator circuits and innovative calibration techniques to overcome the I/Q and frequency-response problems that generally worsen with increasing bandwidth. This enables the MXG to provide modulation bandwidths up to 160 MHz with flatness up to ±0.2 dB and EVM up to 0.4% (Figure 2).

Figure 2: With option 1EA, the MXG provides excellent EVM performance. Click image to enlarge.

One key to this combination of bandwidth and accuracy is the use of an internal calibration source and factory-calibrated channel corrections that extend from the modulator to the RF output. Together, these technologies minimize errors in amplitude, group delay and I/Q, thereby ensuring excellent flatness and modulation accuracy. The combination of calibration source and channel corrections also provides wide modulation bandwidth accuracy without

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