What does an output impedance of 50Ω mean?
The output impedance of an amplifier is an important factor when dealing with fast signals. The speed of the TZA200 is fast enough for this parameter to be relevant. Essentially, the output of the amplifier is a 50Ω resistance in series with the output. This allows you to terminate the signal line with a 50Ω resistance to prevent back reflections. The result is a clean signal transient without overshoot. The disadvantage is that the signal voltage is halved by doing this. The amplifier may be used without the 50Ω termination resistance, but then there will be overshoot when amplifying fast transients.