6-GHz signal generators meet design challenges in radar, military communications and consumer wireless: Page 3 of 6

May 02, 2012 // By Jean-Pierre Joosting
Agilent Technologies has announced four X-Series signal generators that claim unmatched performance in phase noise, output power, ACPR, EVM and bandwidth. With these capabilities, the latest MXG and EXG products (available in analog and vector models) support the development of components and receivers that meet the complex challenges of mitigating interference, speeding data throughput and increasing signal quality in applications such as radar, military communications and consumer wireless.
data rates, modulation bandwidth and distortion requirements. One recent example is the gigabit speed of the emerging IEEE 802.11ac wireless networking standard in the 5 GHz band. Because the 11ac WLAN combines bandwidths to 160 MHz with constellations as dense as 256QAM, it places severe demands on signal generators because achievable modulation accuracy usually declines with increasing signal bandwidth.

The MXG and EXG provide frequency coverage to 6 GHz and modulation bandwidths to 160 MHz or 120 MHz, respectively. This wide modulation bandwidth is available with EVM better than 0.4% and flatness better than ±0.2 dB, ample performance for even the most demanding design tasks.

The X-Series achieves this combination of bandwidth and accuracy through the use of an internal calibration source and factory-calibrated channel corrections that extend from the modulator through the RF output. Together, these technologies minimize I/Q errors to provide high dynamic range and modulation accuracy plus wide modulation bandwidth without user intervention such as manual I/Q adjustment.

Wide modulation bandwidth and high dynamic range provide user benefits when working with signals that are narrower. In today’s crowded spectral environment, receivers must cope with problems such as adjacent-channel interference and multiple types of blocking. For example, a modern smartphone can have three or more transceivers operating at the same time, and must operate in proximity to other devices of similar complexity. The X-Series’ wide-bandwidth modulator can produce a test signal composed of a complete spectral segment that includes the desired signal plus adjacent and alternate channels as potential interferers—and perhaps spurious or transient signals as well.

Automatic routines in the MXG and EXG can use information from a remote USB power sensor to build a measurement of the complex (I/Q) frequency response of the path from the signal generator to the DUT. A real-time ASIC can then perform inverse compensation on the modulated signal to correct the complex channel response at the DUT as shown in Figure

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