There are four different types of feedback topologies based on type of output signal and feedback signal (voltage or current signal). Voltage feedback is taken in series with the load and current feedback is taken in shunt with the load.
They are
a)Voltage-series: Output signal is voltage signal, feedback signal is voltage signal. Also called as series-series feedback. It is employed in voltage amplifiers.
b)Current series: Output signal is current signal, feedback signal is voltage signal. Also called as shunt-series feedback. It is employed in Transconductance amplifiers.
c)Current shunt: Output signal is current signal, feedback signal is current signal. Also called as shunt-shunt feedback. It is employed in current amplifiers.
d)Voltage shunt: Output signal is voltage signal, feedback signal is current signal. Also called as shunt-shunt feedback. It is employed in current amplifiers.
The first word indicates the type of output signal and the second word indicates the manner in which feedback signal is taken whether it is taken in series or shunt with the load.