Based on the picture (as attached), the blue color is the ideal output, whereas the red color is generated from transient simulation. The simulation took place at the frequency of > 300 MHz.
I would like to identify if the clipped voltage (as in red color) is the effect of parasitic capacitance. If yes, I would like to get guide to solve the issue.
Thank you.
Hi Norhamizah Idros ,
if your problem is still unsolved, could you please provide a schematic of your circuit?
Generally, the initial rise time and fall time of the red signal is quite impressive, it's about 100 ps. Consequently, the basic frequency of the signal of about 500 MHz is accompanied by strong harmonics in the GHz domain.
The departure from the ideal blue signal can be due to
a) limited bandwidth; rough estimate: Your bandwidth might be about 2.5 to 3.5 GHz while a signal approximating the blue one would require about 20 GHz.
b) reflections on the signal path caused by impedance variations. With usual basis materials, the wavelength of the 2.5 GHz harmonic is about 60 mm. As a rule of thumb, impedance discontinuities longer than 1/20 wavelength = 3 mm will be visible in your signal.
Additionally, internal processes at the driver or output stage of your circuit might cause deviations from the ideal waveform.
In both the rising edge and the falling edge the initially high amount of d V/d t decreases with increasing time. This effect is probably caused by parasitic capacitance.
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