Today’s sophisticated wireless communication puts many obstacles in the way of developers creating new electronic components and receivers. Whether your business is radar systems, military communications, or consumer wireless devices, the devices you design must be immune to interference, provide high signal quality and throughput.
As engineers achieve new levels of performance, the instruments they use to measure their devices must not only keep up, but even outpace evolving technologies. The X-platform MXG and EXG analog and vector signal generators (Figure 1), operating from 9 kHz to 6 GHz, offer industry-leading performance, allowing you to perform all the necessary tests to determine the real characteristics of components, receivers and other electronic devices.
Industry leading performance
The new models of the MXG series (N5181B and N5182B) feature five improved parameters: phase noise and spectrum purity, signal bandwidth, error vector magnitude (EVM), adjacent channel power ratio (ACPR), and output power. Among other improvements, the typical generator phase noise is -134 dB/Hz with the low phase noise option set to -146 dB/Hz (both at 1 GHz with a 20 kHz offset; Figure 2) . This clean signal combined with -96 dB (typical) spurious levels will help designers achieve significantly better receiver sensitivity.
This performance in the MXG is made possible by the use of a new triple-feedback phase-locked loop (PLL) circuit and the corresponding “frequency plan”. As a result, it was possible to achieve a significant improvement in the characteristics of phase noise near the carrier and at large offsets.
The triple feedback method optimizes the frequency separation, which effectively filters non-linear components, such as specular components, by shifting them outside the synthesizer bandwidth.
Several key problems can be solved with the help of the frequency plan: the choice of the master oscillator and reference frequencies in the summation and bias chain of the synthesizer and the associated frequency conversion (mixers and multiplexers) and filtering. In MXGs, the frequency plan is used to organize reference frequencies and conversions in such a way that shifts the largest non-linearity products away from useful frequencies, with the result that even moderate filtering can greatly suppress the remaining spurious signals.
Modifying Characteristics to Simulate Non-Ideal Generators
The MXG’s phase noise optimization technology makes it possible to selectively and accurately degrade phase noise through a feature called phase noise injection. This is useful when the designer wants to use a signal generator during the design process instead of various master generators and synthesizers.
The MXG’s dedicated real-time signal processing IC allows you to adjust the phase noise levels for both modulated and modulated signals. As a result, you can set different levels of phase noise at different offsets, including near-carrier noise with a steep envelope, synthesizer noise at a medium offset from the carrier with a flat envelope, and noise at a large offset with a flat envelope.
An example of such signals would be OFDM signals like those used in LTE and LTE-Advanced. In addition, phase noise directly affects the EVM, and therefore OFDM receivers and transmitters must have low phase noise. During development, the MXG generator allows you to selectively add phase noise, taking into account the necessary offset from the carrier, simulating synthesizers and OFDM transmitters.
Complex signals with high performance
To help developers quickly create high-quality signals that meet the requirements of specific standards and measurement technologies, the MXG and EXG generators are compatible with Agilent Signal Studio software. This software is designed to create signals used in cellular communications, wireless networks, audio and video equipment, global positioning systems, tracking and general equipment. Signal Studio software has two modes of operation: signal playback mode and real-time mode.
They are used to create and modify finite length waveforms by setting parameters, calculating the resulting waveforms, and transferring files for playback on MXG, EXG, or other Agilent generators. Basic functions provide the creation of partially coded, statistically correct signals to measure the response to a certain impact.
The advanced features support the generation of full channel-coded signals to analyze receiver characteristics such as BER, FER, BLER, and PER. The graphical interface provides a direct connection to the instrument for parameter transfer and automatic or interactive control during real-time waveform generation. For the latest wireless standards, automatic testing is of particular importance, especially when testing the throughput of real channels.
Conclusion
To understand whether the device is working properly, the developer must examine it comprehensively. It is this approach that underlies the X-Series signal generators. They can create all the necessary signals – from simple to complex, from clean to distorted, which allows you to test electronic components and receivers in detail at nominal and extreme conditions. From the precision MXG to the low cost EXG, the innovative X-Series generators will stay ahead of the curve as developers continually improve their performance.
