Lab 1: FET Amplifier


Characteristic of a FET Amplifier 

Grade Weight: 5% of Total Grade

This is a very long lab and will most likely require the full three hours.  Please familiarize with all equipment and requirement below before coming to the lab so that the lab can be completed on time.

Make sure you read both the 'Lab Handout' and the article 'A Dynamic AM/AM  AM/PM Measurement Technique'. Both are required to do this lab.

Lab Handout:
LAB 1 - Operating Characteristics of a Microwave Amplifier (116 kB)

Additional Required Material:
A Dynamic AM/AM and AM/PM Measurement Technique (206 kB) [1]

Lab Report Submission Link:


Please only submit in PDF format, any other format (.odt, .tex, .txt, .rtf, .vim, .doc, .docx, etc...) will not be accepted for marking !!!

Click on the folder below to submit your lab report (it will open the submission form):

FET Amp Lab Report Submissions
Report submission link will be up until the last lab group concludes their lab however the uploaded files are time-stamped and any report that is overdue will not be accepted.

You can keep re-uploading your lab report (for an updated report) until your due date.  The latest version that was uploaded before the due date will be used for marking.

All reports are due 2 weeks after the completion of the report.

i) Please use the following file submission nomenclature:

               Initials (first name, last name) _ Student number _ vX_FET_Lab.pdf

As an example, if this was your name, student number, and submission version:
  • Student Name: Shakeeb Abdullah
  • Student Number: 100988283
  • Version Submission: v0
Then you would name your submission file as:

              SA_100988283_v0_FET_Lab.pdf

ii) Your first submission will be v0.  Every time you re-upload your report, increase the version number by 1.  Ex. next iteration of project upload would be:

              SA_100988283_v1_FET_Lab.pdf


Announcements (MUST READ IMPORTANT SECTION!!!):

1) Materials and Apparatus:
  • Spectrum Analyzer - Please do not exceed input power level of 27 dBm (30 dBm max), you can end up blowing the front end and destroy the machine!!!:
  • Signal Generators - Please allow the generators to warm up for 5 min - 10 min before use.  Remember to turn off RF output when not using the generator:

  • 0-9 dB and 0-60 dB Attenuators - Make sure to characterize the attenuators before using them.  A 5 dB attenuation may not actually be 5 dB, it may be 4.5 dB due either being defective or to wear & tear and use over its lifespan:

  • Amplifer - Do not use any more than 5.1V on the amplifier:

  • Splitter/Combiner - Please use the device in the correct order:

  • Power Supply - Remember to turn off the power supply when not using the amplifer:
  • Different types of connectors - look at the document in the next point to familiarize yourself with the different types of connectors:

2) Transfer Characteristic and Harmonic Distortion Measurements:

  • Start with 60 dB attenuation and go to 59 dB, 58 dB, .... 0 dB.
  • If you are having a hard time seeing a good signal on the spectrum analyzer, try these settings and adjust accordingly: 

    • Ref Level: 10.00 dBm
    • Attenuation Manual: 20.00 dB
    • Scale/Div: 7 dB
    • Start Frequency: 1.5 GHz
    • Stop Frequency: 4.5 GHz
    • Sweep Time: 800 ms
    • Sweep: Continuous

3) Two-Tone Intermodulation Measurements:
  • Start with 60 dB attenuation and go to 59 dB, 58 dB, .... 0 dB.
  • If you are having a hard time seeing a good signal on the spectrum analyzer, try these settings and adjust accordingly:

    • Ref Level: 10.00 dBm
    • Attenuation Manual: 20.00 dB
    • Scale/Div: 7 dB 
    • Start Frequency: 1.975 GHz
    • Stop Frequency: 2.025 GHz 
    • Sweep Time: 800 ms
    • Sweep: Continuous

 4) AM Compression and AM/PM Conversion: 
  • For lab report calculations use:
  • If a signal is in the noise floor, use 0 V during calculations.
  • Make the initial reference measurements at 40 dB attenuation; where the signals have relatively no distortion and are linear.
 
  • Make the phase change measurements starting at 39 dB of attenuation and go to 0 dB.
  • If you are having a hard time seeing a good signal on the spectrum analyzer, try the same settings as the two-tone test.

Lab Report Requirements:


  • Have a section on equipment set-up for each measurement section so if there is an issue, the experiment can be duplicated by a third party and the error can be spotted.
  • Answer the questions concisely (get to the point and make it clear).  Use full sentences but do not write an essay.  For example Qu. 1 asks to plot the transfer characteristic, calculate the gain and plot gain vs input power;  then just plot the transfer graph, give the calculations for gain, and then plot the gain vs power in the same order - but use full sentences in concise form. 
  • Make sure to properly label all figure captions and table captions.
  • Make sure to properly label axes titles and units on graphs.  Also have a title on your graph clarifying what is being seen.
  • When describing a curve fit on your graph, don't label your curve fits with all x and y variables {ex. y = 0.435x + 60.1}, make the variables clear {ex. Vout (V) = 0.435 (Ī©) *Iin (A) + 60.1 (V)}.
  • Always show a sample calculation wherever applicable.
  • Include all your observed and measured data during the lab in an Appendix at the end of your report.  Present the data in a clean formatted table.
  • Qu. 2 in Discussion: Give the difference in dB for both when the harmonic is introduced and when the signals are fully saturated.


Demo of the Lab During COVID-19 [Fall 2020]:



Additional Resources:

 

1. Convert Nepers to dB: http://www.sengpielaudio.com/calculator-neper.htm
2. What is a dB: https://www.rapidtables.com/electric/decibel.html


References:


[1] A. A. Moulthrop, C. J. Clark, C. P. Silva and M. S. Muha, "A dynamic AM/AM and AM/PM measurement technique," 1997 IEEE MTT-S International Microwave Symposium Digest, Denver, CO, USA, 1997, pp. 1455-1458 vol.3.