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Agilent Microwave Component Measurements Amplifier Measurements Using the Scalar Network Analyzer Application Note 345-1 Introduction A scalar network analyzer provides fast, economical The Agilent 8757A is a powerful, easy to use scalar ana- measurements of many amplifier parameters. This note lyzer. It provides three detector inputs (a fourth input is describes gain, gain compression, isolation, and return optional), and four independent display channels. With loss (SWR) measurements using the Agilent 8757A the 11664A/E Detectors, the 8757A offers -60 dBm sensi- Scalar Network Analyzer and the Agilent 8350B Sweep tivity at sweep speeds as fast as 50 ms. With the Agilent Oscillator to illustrate the techniques. Definitions and 85025A/B Detectors and the Agilent 85027A/B/C specific step-by-step instructions are included, along Directional Bridges, the 8757A offers the choice between with a description of accuracy considerations. The two detection modes. In AC mode, the detectors detect system features, such as alternate sweep, power sweep, the envelope of signals modulated by a 27.778 kHz square trace cursor and pass/fail limit lines are described. wave. This modulation is provided internally by the Agilent 8350B sweep oscillator. Spurious unmodulated All measurements described in this note are possible signals and broadband noise are undetected. In DC detec- without the use of a computer. However, it is possible to tion mode modulation is not required, and the detector automate these measurements using the same measure- responds to all signals in its frequency range. ment sequences. For more information on the Agilent 8757A and amplifier measurements, refer to the refer- ences listed on page 15. This note describes how scalar network analysis can be used to measure several important amplifier parameters as a function of both frequency and input power. It is important to keep in mind that many other factors can affect amplifier performance, such as bias level, temper- ature, and time. In amplifier measurements, all these variables must be taken into account for complete device characterization. Equipment required The following equipment is used in the measurements described in this note. 8757A Scalar Network Analyzer 8350B/83592A Sweep Oscillator* 85027B Directional Bridge 85025B Detectors 11667B Power Splitter 85023B Verification Kit 85022A system cable kit * The 8350B Sweep Oscillator is used in all of the following measurement setups. An 8340B or 8341B Synthesized Sweeper could also be used for ap- plications requiring higher frequency accuracy and stability. When higher