ELEG 3224 Lecture 5: Effect of Output Resistance of the Current-Source Load, Common Gate and Common Base Amplifiers

• School: University of Arkansas
• Department: Electrical Engineering
• Course: ELEG 3224
• Professor: Alan Mantooth

Document Summary

Lec 5 effect of output resistance of the current- Effect of the output resistance of the current-source load. Occurs since the ideal current source is not ideal and will have a finite output resistance. Resistance will appear in parallel with output resistance of since both are connected to. This result shows that gain was reduced from to . If both transistors have equal early voltages then that means , and the gain is reduced by half ground upon small signal analysis. Cg and cb amplifiers proved good implementations of current buffers. Current buffers pass current but raise the resistance level. Simple current mirror can rewrite the voltage loop equation as. By adding up the voltages through the red loop shown we can get the equation. Can be found by applying test voltages and currents to the input and finding. It is obvious from the diagram that is the negative of , or .