Optimizing RF and Microwave Spectrum Analyzer Dynamic Range Application Manual

Optimizing RF and Microwave Spectrum Analyzer Dynamic Range Application Manual
Pages 16
Views 189
Downloads : 2 times
PDF Size : 137.6 KiB

Summary of Contents

Optimizing RF and Microwave Spectrum Analyzer Dynamic Range Application Manual

  • Page 1

    Agilent AN 1315Optimizing RF and MicrowaveSpectrum Analyzer DynamicRangeApplication Note•••• ••••Agilent TechnologiesInnovatingtheHP Way

  • Page 2

    23334445677779101011111212131314151. IntroductionWhat is dynamic range?Why is dynamic range important?2. Dynamic Range InterpretationsMeasurement rangeDisplay rangeMixer compressionInternal distortionNoiseSensitivityPhase noiseSecond- and third-order dynamic rangeSummary3. Making Harmonic or Inte...

  • Page 3

    3What is dynamic range?The dynamic range of a spectrum analyzer is tradi-tionally defined as the ratio, in dB, of the largest to the smallest signals simultaneously present atthe input of the spectrum analyzer that allowsmeasurement of the smaller to a given degree ofuncertainty. The signals of i...

  • Page 4

    4Figure 1 shows several different interpretations fordynamic range. In this chapter we will explaineach interpretation.Measurement rangeThe measurement range is the difference betweenthe largest and smallest signals that can be meas-ured on a spectrum analyzer, allowing for differentinstrument se...

  • Page 5

    5Mixer compressionThe mixer compression level is the maximumpower level that we can put into the analyzer with-out compromising the accuracy of the displayedsignal. When the signal level at the mixer is wellbelow the compression point, the level of thedesired mixing product (IF signal) is a linea...

  • Page 6

    6Internal DistortionInternal distortion is one of the factors that determines the dynamic range when measuringdistortion products, such as harmonic distortionfrom a single tone or the intermodulation distortionfrom two or more tones. The internally generatedintermodulation and harmonic distortion...

  • Page 7

    7NoiseTwo types of noise contribute to dynamic range:phase noise and sensitivity. Noise is a broadbandsignal; therefore, as the resolution bandwidth(RBW) filter is widened, more random noise ener-gy is allowed to hit the detector. This increases thelevel of phase noise as well as the noise floor ...

  • Page 8

    8Therefore, the DANL curve is a straight line havinga slope of –1 (see Figure 4). The horizontal line at–80 dB in Figure 4 represents phase noise, ratherthan DANL, for a 10 kHz offset and 10 Hz RBW.Phase noise is the limiting factor when makingmeasurements close to the carrier (<1 MHz away...

  • Page 9

    9SummaryA popular use of a spectrum analyzer is to meas-ure harmonic or intermodulation distortion prod-ucts. Measurement range, display range, and mixercompression do not take into account all of therestrictions encountered when making these typesof measurements. Therefore, “dynamic range” i...

  • Page 10

    10Measurement uncertaintyTheoretical dynamic range calculations do notaccount for measurement uncertainties. If internallygenerated components occur at the same frequen-cies as the signals that we want measure, as is thecase in distortion measurements, our accuracy willbe degraded. Depending on ...

  • Page 11

    11Optimizing measurementsPreamplifierA preamplifier is useful when measuring low-levelsignals. There are two important factors to considerwhen choosing a preamplifier: gain and noise fig-ure. The noise figure (NF) of the preamplifier mustbe lower than the NF of the spectrum analyzer(NFSA= DANL + ...

  • Page 12

    12AttenuatorAs discussed earlier, when measuring distortionproducts it may be necessary to adjust the powerlevel at the mixer. If the power level at the mixer islow enough, we can be guaranteed that the distor-tion products we are seeing are from our Device-Under-Test (DUT). However, if the power...

  • Page 13

    13RBW filter Since noise is a function of the RBW filter, use caution when interpreting phase noise or DANLspecifications.Phase noise specifications are normalized to a 1 HzRBW filter even if the analyzer does not have a 1 Hz RBW filter. In order to determine the actualachievable phase noise leve...

  • Page 14

    14Dynamic range limits the range of signal ampli-tudes we can measure with a spectrum analyzer.There are several interpretations of dynamic range,including measurement range, display range, mixercompression, internal distortion, and noise; theapplicable interpretation depends on the type ofmeasur...

  • Page 15

    15Pub. number1. Spectrum Analysis Basics,Agilent Application Note 150 5952-02922. Effective Spectrum Analysis Testing for Consumer Electronics Production Lines,Agilent Application Note 130 5966-0367E3. Spectrum Analyzer Measurements and Noise,Agilent Application Note 1303 5966-4008E4. Agilent ESA...

  • Page 16

    By internet, phone, or fax, get assistance with all your test and measurement needs.Online Assistancewww.agilent.com/find/assistPhone or FaxUnited States:(tel) 1 800 452 4844Canada:(tel) 1 877 894 4414(fax) (905) 206 4120Europe:(tel) (31 20) 547 2323(fax) (31 20) 547 2390Japan:(tel) (81) 426 56 7...