Connecting one stage to the other

[zesla]

Hello guys,

I just want to generally know what are the main considerations when connecting 2 stages (input to output and vise versa) to each other. The Stages I mean can be everything (for instance connecting a microphone to an input, or connecting an output to a speaker and specially connecting two active stages like a preamplifier to an amplifier or a transistor stage to an op-amp or to other transistor stages). I want to know if all those follow a similar rule.

Thanks.

 

[MikeMl]

Active stages that have different DC levels in/out may require DC blocking caps if the signals are audio. If you need response down to DC, then the two active stages must be designed such that the DC component of the signal out of stage 1 is compatible with the bias requirements for stage 2.

 

[Nigel Goodwin]

Ignoring any DC considerations (already mentioned above) you need to be concerned with impedances - you must have low impedance outputs feeding high impedance inputs, as a 'rule of thumb' the inputs need to be a minimum of five times the output impedance.