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I am getting different bandwidth measurements from my breadboard and PCB (for the same circuit with exact same component values). The cut-off frequency I measure on the breadboard is slightly higher than that of the PCB. I though breadboards have a higher parasitic capacitance due to their area. But then shouldn't the breadboard bandwidth be lower than that of the PCB? Is there a comparison I can make between breadboard and PCB parasitic capacitances? Or is there something else causing this difference?

Thanks :)

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  • \$\begingroup\$ You'd think so, wouldn't you? It's probably true most of the time but consider that you can overcome the RC time constant in a resistor divider and increase it's bandwidth by placing a capacitive divider in parallel with it which allows the high frequencies to bypass other parasitic capacitances. \$\endgroup\$
    – DKNguyen
    Commented Apr 24, 2022 at 17:17

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Even if you use the exact same component values, the components have some tolerance like 5% or 10% so it may be the reason why the bandwidth is different.

It also depends on breadboard and PCB design. Breadboard might have stray capacitances between nearby traces as there might be no ground plane. The PCB might have stray capacitances not between traces but to ground if it is a two layer design with a ground plane.

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