Interpreting magnitude of HSPICE's FFT-output of mixed signals

Click For Summary
SUMMARY

The forum discussion centers on interpreting the FFT output from HSPICE simulations of mixed signals, specifically focusing on analyzing the frequency content of transient current draw. The user seeks clarification on whether the magnitude on the Y-axis of the spectral density curve represents the real amplitude of current at specific frequencies. A key conclusion is that impedance is not necessary for calculating noise voltage; instead, the Power Spectral Density (PSD) of the signal itself should be utilized for accurate analysis.

PREREQUISITES
  • Understanding of HSPICE simulation tools
  • Familiarity with FFT (Fast Fourier Transform) analysis
  • Knowledge of Power Spectral Density (PSD) concepts
  • Basic principles of electrical impedance
NEXT STEPS
  • Research HSPICE FFT analysis techniques
  • Learn about interpreting Power Spectral Density (PSD) in signal processing
  • Explore the relationship between current amplitude and impedance in frequency analysis
  • Study advanced noise analysis methods in power systems
USEFUL FOR

Electrical engineers, circuit designers, and anyone involved in power systems analysis who needs to interpret FFT outputs for mixed signals in HSPICE simulations.

prasfft
Messages
1
Reaction score
0
I ran a time-domain simulation in HSPICE & I am trying to analyze the frequency content of the transient current draw...(FYI- I have the power systems "impedance vs. frequency" curve, and my aim is to determine the noise voltage on my power rail given its impedance now)

So I run FFT (current-waveform,t_start, t_stop, NP) using the in-built calculator...

Now how does one interpret the resulting spectral density curve?

Is the magnitude (on Y-axis) the real amplitude of current at that frequency i.e. can I just take that amplitude and multiply it by impedance Z at that frequency to calculate the noise voltage...??

I'd highly appreciate if some one can lend insight into this...thanks a bunch
 
Engineering news on Phys.org
You don't need impedance at all. Just use the FFT (actually PSD) of the signal itself.
 

Similar threads

Improving Frequency Resolution with Window Functions in FFT Calculations
  • · Replies 3 ·
Replies
3
Views
2K
FFT and Resistor Noise Newbie Questions - PLEASE HELP
  • · Replies 4 ·
Replies
4
Views
3K
How to Measure High and Low Impedance Accurately?
  • · Replies 7 ·
Replies
7
Views
3K
Voltage Output in subtractor photocircuit
  • · Replies 1 ·
Replies
1
Views
2K
Available Noise Power and Amplifiers
  • · Replies 1 ·
Replies
1
Views
2K
Bootstrapping Amplifiers, and Signal Bypasses
  • · Replies 4 ·
Replies
4
Views
2K
Graduate Calculating Magnetic Field Strength from FFT
  • · Replies 10 ·
Replies
10
Views
3K
Graduate Calculating Magnetic Field from FFT Amplitude
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Understanding Fourier Transforms
  • · Replies 1 ·
Replies
1
Views
2K
How Can I Improve Signal Transmission and Reduce Noise in High Magnetic Fields?
  • · Replies 2 ·
Replies
2
Views
3K