Column Control DTX

High Power Amplifier Measurements Using Keysight VNAs

Application Notes

Introduction 

High-power amplifiers are a common building block of RF and microwave communication systems. Mobile phones, used by millions of users, contain high-power amplifier chips. Satellite systems and base-stations used for transmitting data depend on a multitude of solid-state or traveling-wave tube power amplifiers. Characterizing the performance of high-power amplifiers is a critical factor in the design and verification process. 

Table of Contents 

Power Budget Analysis and MW PNA Block Diagram 

  • Example A: Dual-band handset amplifier for GSM900 and DCS1800 
  • Example B: Ku-Band solid state power amplifier 

Step-by-Step Guide for Measuring a High Power Amplifier 

Alternative High-Power Configurations 

FAQ  

  • How do I know if the network analyzer receivers are compressed? 
  • The uncalibrated results seem reasonable, but the calibrated data appears incorrect. What could be the cause? 
  •  What is the power of the network analyzer at start-up or preset? 
  •  What is the power level of different measurement channels at preset?  
  •  Can different measurement channels have different power levels? 
  •  Can I use this setup to make hot S22 measurements?  
  • What happens to the power level when RF power is turned off during a sweep?  
  • Is there a power limitation on the mechanical components of a calibration kit?  
  •  Is there a power limitation on electronic calibration or ECal? 
  •  What are the benefits of a source-power calibration? 
  •  What is the optimum power level for calibration?  
  • What happens to the power level at each port during various measurements?  
  •  What happens to the two-port calibration if the source or receiver attenuation is changed 
  • What does the error message “source unleveled” signify? 
  • What happens to the PNA output power during re-trace? 
  •  What happens to the RF power during frequency band-crossings? 

Appendix A: Maximum Power Levels for PNA and PNA-L Network Analyzers 

Appendix B: Understanding PNA measurements with an external reference

signal and source attenuator changes

 

Power Budget Analysis and MW PNA Block Diagram SourceR2B35 

One of the main factors to consider in a high-power network analyzer measurement is the power-handling capability of the internal components of the network analyzer. High power levels can damage the network analyzer, and it is costly to repair the internal components of the network analyzer. In addition to damage level, compression level, and noise levels also have to be considered in a high-power setup.

The initial step in a high-power measurement is a calculation of the power budget or a power-flow analysis. In this section, we examine the block diagram of a PNA network analyzer, followed by two examples of power-flow analysis.  

Figure 1 shows the block diagram of the 20 GHz E8362B1 MW PNA network analyzer. Table 1 lists the damage level for the components of the 20/40/50 GHz E8362/3/4B PNA. Damage and compression power levels for the 67 GHz E8361A PNA can be found in the Appendix. In general, we recommend that components not be operated near damage level and the power level be kept at least 3 dB (preferably 6 dB) below damage level. The user should be aware that the optimal level could be well below the damage level, as is the case with the receivers. 

Why is the damage level listed at the test port +30 dBm, but +43 dBm for the coupler? Isn’t the coupler located right at the test port? 

Yes. The coupler is right at the test port, but while the coupler can handle up to +43 dBm (<20 GHz), the bias-tees (which are located immediately after the coupler) have a damage level of +30 dBm. 

Therefore if more than +30 dBm is applied to the test port, the bias-tees will be damaged. The receiver attenuators also have a +30 dBm damage level, but they can be protected with attenuation placed between the CPLR ARM and RCVR A IN jumpers. There is no jumper between the coupler and the bias-tee, so there is no way for a user to decrease the power between the coupler and the bias-tee. Thus the power at the test port should be limited to less than +30 dBm. If you want to take advantage of the high-power capabilities of the coupler, there are two options. One is to purchase an instrument without the bias-tees (and source attenuator, which is coupled with the bias-tees under option UNL). The second alternative is Keysight’s special MW PNA, E836x-H85. Special Option H85 adds the source attenuators, but not the bias-tees.

×

Please have a salesperson contact me.

*Indicates required field

Preferred method of communication? *Required Field
Preferred method of communication? Change email?
Preferred method of communication?

By clicking the button, you are providing Keysight with your personal data. See the Keysight Privacy Statement for information on how we use this data.

Thank you.

A sales representative will contact you soon.

Column Control DTX