So, even bipolar amplifiers with “low” output impedance can have imperfect gain and linearity due to thermal feedback from the output transistors to the input stages. ON THE BENCH ...

This high output impedance usually occurs on rail-to-rail outputs, which are “drain-loaded.” You can’t have an emitter-follower or source-follower output on a rail-to-rail output!

It’s common practice to series-terminatean op amp to match theimpedance of the load. This practicecauses a 3-dB loss of output power in thetermination resistance, however (Figure1 ). Newer op amps ...

Output-impedance measurements The simplest solution is to measure the output impedance of the op amp, in-circuit, using a 1-port reflection measurement in a VNA (vector-network analyzer). The VNA is ...

The input impedance matching is important. Due to the bias currentfrom the positive and negative input port, input impedance mismatchleads to input offset voltage. The input offset voltage will ...

Simply stated, it is the ratio between the nominal load impedance (typically 8W ) and the source impedance of the amplifier. Note that all modern amplifiers (with some extremely rare exceptions) are, ...

The output impedance of an emitter follower is significantly lower than that of a common emitter amplifier, allowing it to drive much more demanding loads.