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Matching or not matching ?

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firebird

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Hi there. I am relatively new to electronics and I have a question. Suppose you want to connect two circuits togheter, such as two op-amp circuits for instance. So, would it be better to work with matched impedances or would it be better if the first circuit has a very low output impedance and the last circuit has a very high input impedance ?

Thanks for your help.
 
firebird said:
Hi there. I am relatively new to electronics and I have a question. Suppose you want to connect two circuits togheter, such as two op-amp circuits for instance. So, would it be better to work with matched impedances or would it be better if the first circuit has a very low output impedance and the last circuit has a very high input impedance ?

Thanks for your help.

For maximum signal transfer you feed a low impedance in to a high impedance, you don't need VERY low, and VERY high - ten times the impedance is usually fine.

Matching impedances gives maximum POWER transfer, but by definition attenuates the signal by 50%.

You can work it out quite simply by ohms law, it's simply an attenuator (or potential divider).
 
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