How to plot AM/AM and AM/PM Characteristic using input and output baseband signals?
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I have .txt files that contain complex input and output baseband signals of an amplifier. I need to plot the AM/AM (magnitude of Gain vs. Input power) and AM/PM (phase of Gain vs. Input power) Characteristic.
% Calculate input and output power
P_in = 30 + 10*log10( (abs(x_in).^2)/100); % x_in is the input baseband signal
P_out = 30 + 10*log10((abs(x_out).^2)/100); % x_out is the output baseband signal
% Calculate gain
Mag_Gain = P_out - P_in;
Phase_Gain = rad2deg((angle(x_out) - angle(x_in)));
% Then I plot the AM/AM and AM/PM curves
% however the results does not match with the theoretical results.
% Is the way for calculating the power correct?
1 Comment
Laxmikant
on 17 Jan 2025 at 10:27
Hi Zainab,
Have you find the right way to to get AM-AM plot and AM-PM plot?
could you share your result?
I also have PA input singal and output signal from PA but not sure I am doing things in right way or not. My AM-AM plot is spread over large area.
Thank you.
Accepted Answer
Aditya
on 21 Nov 2024
Hi Zainab,
There's limited information to fully address your query, but from the equations you've shared, your calculations for power seem correct. Here are a few things you might consider to resolve the issue:
- Check Unit Consistency: Ensure that all units (e.g., dBm, dB) are consistent throughout your calculations.
- MATLAB Central Resource: You might find this MATLAB Central File Exchange post helpful: https://www.mathworks.com/matlabcentral/fileexchange/173930-plots-am-am-and-am-pm?s_tid=answers_rc2-1_p4_MLT
If this doesn't resolve the issue, please attach the output that you are getting and the theoretical output.
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