Current buffer examples Buffer amplifier
figure 6: bipolar current follower biased current source ie , active load ic
figure 6 shows bipolar current buffer biased current source (designated ie dc emitter current) , driving dc current source active load (designated ic dc collector current). ac input signal current iin applied emitter node of transistor ac norton current source norton resistance rs. ac output current iout delivered buffer via large coupling capacitor load rl. coupling capacitor large enough short-circuit @ frequencies of interest.
because transistor output resistance connects input , output sides of circuit, there (very small) backward voltage feedback output input circuit not unilateral. in addition, same reason, input resistance depends (slightly) upon output load resistance, , output resistance depends on input driver resistance. more detail see article on common base amplifier.
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