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Generating Custom, Real-World
Waveforms for 3G Wireless
Applications
Product Overview
Introduction then measured with a vector signal analyzer such
As a system designer, have you ever needed to as the Agilent 89440 Series Vector Signal Analyzer
know the system specification at the input or out- (VSA). If the ACPR specification is not met, then
put of specific components along the design flow, the parameters or system components in the trans-
only to be thwarted by the inability to either meas- mission chain can be changed to alter the ACPR of
ure the specification through instrumentation or the signal at the input of the power amplifier. Or,
simulate the specification with software? Suppose, as alternatives, a power amplifier with different
for example, that you have an ACPR specification ACPR characteristics can be selected, or the power
for the entire transmission chain and you want to amplifier itself can be modified.
know the allowable ACPR specification before the
input of the power amplifier. The system has been Using our example, other types of system specifica-
simulated in software, you know the simulated tions can also be measured, such as Error Vector
ACPR up to the input of the power amplifier, and Magnitude (EVM), Bit Error Rates (BER), and
the specific power amplifier has been chosen, but Frame Error Rates (FER) on the receiving chain,
is it the right power amplifier for the system? and also spur analysis. The signal created by
Before continuing on with the design you want to Advanced Design System can also include real-
send the simulated signal, with known ACPR, world impairments such as multiple scattering
through the actual power amplifier to measure at noise, IQ offset errors, filter group delay, and mul-
the output of the power amplifier this very impor- tipath fading. Using the same signal in the simula-
tant specification. tion and on the actual hardware component
removes the uncertainties associated with correlat-
A few years ago, your only option would have been ing measured and modeled results.
to continue with the design, with no way of knowing
whether the system design met the ACPR specifica- Another challenge facing RF and DSP system
tion until after the prototype was fully built and designers at the forefront of technology is to be
measured. Today, it is possible to integrate the able to create the needed signal formats and modu-
testing of partially completed software and hard- lation schemes for tomorrow's standards.
ware designs by combining the signal simulation Advanced Design System can interface with ESG-D
capabilities of Advanced Design System, EDA soft- to create custom test signals. Linking electronic
ware from the Agilent EEsof EDA product group with design automation (EDA) tools with measurement
the signal generation capabilities of the Agilent equipment decreases the time needed to evaluate
Technologies ESG-D series signal generator. and troubleshoot the system. This link between the
design environment (ADS) and test and measure-
In our example, the signal is created in Advanced ment environment (ESG-D and VSA) bridges the
Design System and sent to the arbitrary waveform gap between conceptual design and prototype/test
generators of the ESG-D to create a real-world sig- phases.
nal for input into the power amplifier. The ACPR is
2
The Advanced Design System/ESG-D link, when Basic Structure of Advanced Design System
used with Design Libraries from Agilent EEsof ESG-D Link
EDA, such as W-CDMA, GSM, or cdma-2000-compli- As shown in Figure 1, the data generated by an
ant, can greatly reduce your system design time. Advanced Design System simulation is transmitted
to the ESG-D through an GPIB interface. By using
Features include: the arbitrary waveform generator in the Agilent
ESG-D Signal Generator, the analog I and Q wave-
