Memory

David E. Root; Jan Verspecht; Jason Horn; Mihai Marcu

doi:10.1017/CBO9781139042970.007

6 - Memory

Published online by Cambridge University Press: 05 October 2013

Jason Horn and

David E. Root: Affiliation:
Agilent Technologies
Jan Verspecht: Affiliation:
Agilent Technologies
Jason Horn: Affiliation:
Agilent Technologies
Mihai Marcu: Affiliation:
Agilent Technologies

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Summary

Introduction

X-parameters were introduced in Chapter 2 as frequency-domain nonlinear mappings. The X-parameter functions are defined on the complex amplitudes of the incident CW signals, returning the complex amplitudes of the scattered CW signals. For fixed power, bias, and load conditions, these input and output amplitudes are constant (in time) complex numbers. As such, X-parameters were defined only for steady-state conditions.

Real applications deal with signals that vary in time and the corresponding time-varying responses of DUTs to such stimuli. In particular, signals used in wireless communications can have independent time-varying values for the amplitudes and phases associated with each of the multiple carriers involved. These time-dependent modulations contain the information associated with the signal. Much of communication systems design is devoted to trying to preserve the information content of these signals while efficiently amplifying, transmitting, and then demodulating them at the receiver to recover the information.

This chapter introduces the notion of dynamics into the signals and into themappings between input and output stimuli that define the DUT as a nonlineardynamic system. The envelope domain is introduced to define the class of signalsconsidered. Quasi-static applications of static X-parameters are introduced as methodsfor estimating the DUT’s response to modulated signals, and limitations are discussed.Examples are provided of phenomena that require the abandonment of thestatic nonlinear system description. This introduces the notion of memory, where theresponse of the system depends not only on the instantaneous value of the inputsignal, but also on the history of the input signal. The concept of modulation-inducedbaseband memory is articulated.

Information

Type: Chapter
Information: X-Parameters
Characterization, Modeling, and Design of Nonlinear RF and Microwave Components
, pp. 150 - 188

DOI: https://doi.org/10.1017/CBO9781139042970.007 [Opens in a new window]

Publisher: Cambridge University Press

Print publication year: 2013

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References

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