ch3-5

Another types of F.B
3- the current shunt

The AC schematic diagram of the third type of single loop feedback amplifier, the current shunt amplifier, a cascade interconnection forms the open loop, while the feedback subcircuit comprises a single resistance, The output voltage, is sampled by and converted into a current which is fed back to the input port. Therefore, both the driving point input and output resistance are very small. Accordingly, the circuit operates best as a transresistance amplifier in that its closed loop transresistance, is nominally invariant with source resistance, load resistance and transistor parameters.

4- the voltage series
the work of voltage series feedback amplifier is the transistors are embedded in the open loop amplifier and the feedback subcircuit is provided by resistor combined with local feedback resistors and The feedback network samples the output current, and compares it with the input voltage. Therefore, both the driving point input and output resistance are very high, and, accordingly, the circuit operates best as a transconductance amplifier in that its closed loop transresistance, is nominally invariant with source resistance, load resistance and transistor parameters.
From a comparison of voltage-series feedback with voltage-shunt feedback amplifier, it is apparent that the only difference between the two amplifiers is the load resistance. Therefore, unless some minor differences we can follow the same analysis we have previously developed for the voltage-shunt amplifier with output buffer.