IEEE Std 1770:2021 pdf free download – IEEE Recommended Practice forthe Usage of Terms CommonlyEmployed in the Field of Large-Signal Vector Network Analysis
3.3.1 Large-signal network analyzer
A large-signal network analyzer is a network analyzer equipped to measure both the magnitude and phase,with respect to a given time reference, of the large signal forward and backward waves at its ports. Thesewaves most often include a distinct, commensurate set of spectral components.
NOTE 1—As an example, a large-signal network analyzer(LSNA)can be used to measure harmonics, subharmonics, andintermodulation products produced by nonlinear devices, such as when stimulated by a sufficiently large amplitude inputsignal consisting of a single fundamental frequency or multiple tones, respectively.
NOTE2—The term sampler-based LSNA refers to LSNAs based on temporal sampling circuits, while a mixer-basedLSNA refers to LSNAs based on mixer technology (see[B6],[B7],[B8],[B9). Sampler-based LSNAs often can quicklycapture modulated signals and long time records,while mixer-based LSNAs often exhibit improved dynamic range.However, the distinction between the two is somewhat artificial, as there is a continuum of sampling technology used inLSNAs spanning sampling circuit and mixing technologies.
NOTE3—In the past, some have used the term “large-signal network analyzer” to refer to sampler-based LSNAs, and theterm “nonlinear vector network analyzer” to refer to mixer-based LSNAs.However,LSNAs are designed to operate in alinear state.This is often accomplished by adding attenuators before theLSNA’s receivers to ensure that they remain lineareven when signal levels are high. The terminology “nonlinear vector network analyzer,” which implies that the LSNA isitself nonlinear, can be misleading.Using the terminology “”sampler-based/mixer-based LSNA” is clearer than using large-signal network analyzer or nonlinear vector network analyzer to distinguish between the underlying sampler technology,and thus preferred.
NOTE4—Recall that for a vector network analyzer (VNA) used for small-signal network analysis, its key characteristicis that it measures the various sinusoidal traveling waves at the input and output ports of the device under test (DUT)at the same frequency as the stimulus sinusoidal traveling wave and at no other frequencies. It is well known thatthe distinguishing feature of a linear versus nonlinear DUT is that a linear DUT produces no other frequencies whenstimulated with a single frequency, whereas a nonlinear DUT can produce integer harmonics, other types of harmonics(e.g., subharmonics or quasiperiodic set of harmonics), or even a continuous interval of frequencies (known as chaos),given a single input frequency. For most applications, the nonlinear DUTs only produce integer harmonics/subharmonics(including the important zeroth harmonic or dc response) of the single input frequency.For a DUT with a finite bandwidth(that is, essentially all real DUTs),one can say that the VNA measures only the fundamental inputs and outputs of the DUT(that is, output frequencies identical to the input frequencies), whether it is linear or not. In contrast, the generalization ofthe classical VNA, termed here as an LSNA, can measure not only the fundamentalinputs and outputs, but also the variousdistinct spectral components that are naturally produced by a nonlinear DUT, all in a traceable manner.