What’s the basic difference between a current feedback amplifier (CFA) and a voltage feedback amplifier (VFA)?

Simply put, in VFA the positive node Vp tracks the negative node Vn by action of negative feedback. In a CFA, however, the tracking happens by design.

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CFAs haven’t been around for as long as VFAs and are still less popular compared with their VFA counterparts, but they do offer great benefits when used in the right application.

Some key benefits of CFAs are their high bandwidth, extremely high slew rate and low distortion making them suitable for large transient interface including audio applications. Check out the LME49723 to appreciate the low noise and low distortion.  On the other hand, CFAs typically lack the precision of VFAs and can have large amounts of input bias currents which can result in a higher current noise density. They also have mismatched impedances at their inputs (low input impedance at the negative node) as a buffer is used internally between the inverting and non-inverting inputs.

Learn more about CFA’s and VFA’s here!

 

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