pole-zero location

The transfer function of a compensator is given as $${G_c}\left( s \right) = {{s + a} \over {s + b}}$$ $${G_c}\left( s \right)$$ is a lead compensator if

A lead compensator used for a closed loop controller has the following transfer function $${\textstyle{{K\left( {1 + {s \over a}} \right)} \over {\left( {1 + {s \over b}} \right)}}...