Total Harmonic Distortion tests and results, part 2 – 20 KHz performance

Total Harmonic Distortion performance at 20 KHz.

Next step is to test performance of all stages at higher frequencies.  All tests are performed in the same manner as in previous testing.  Inputs of all 4 stages are connected together and transfer function of every stage is modified to have Gain=1 with corresponding loads and at 20 KHz. Read more

Total Harmonic Distortion tests and results

Test setup for THD measurements.

I will use my Total Harmonic Analyzer for LTSPICE to perform these tests. Control script is slightly modified, to decrease test (simulation) time. It is possible to do so, because all schematics are settling fast and we are not looking into very small THD numbers. Signal amplitudes are also of moderate values. Read more

Audio Total Harmonic Distortion Analyzer for LTSPICE, making THD vs. Amplitude and Frequency sweeps in LTSPICE

FFT capabilities integrated into LTSPICE simulator are nice and flexible. However, if you would like to evaluate frequency or amplitude dependence of distortions, you have to take these measurements point by point and then manually plot them.

I created an LTSPICE add-on to automate THD measurements and plot result in the form of THD vs. Amplitude and THD vs. Frequency graphs. Read more

Distortion measurements with LTSPICE

LTSPICE is offering good capabilities for distortion analysis and simulations. All you have to do is to run transient analysis and then right click on the signal plot and use FFT command from view section of submenu. Or use .FOUR command and look for results in SPICE error LOG file from View menu. Though, you have to change a couple of default settings to be able to simulate and analyze harmonics, lower than – 60dB. Read more