Why Are RL and RC Considered Parallel in Common Emitter Amplifier AC Analysis?

AI Thread Summary
In AC analysis of a common emitter amplifier, RL (load resistor) and RC (collector resistor) are considered to be in parallel due to the low impedance path created between ground and Vcc. This assumption is valid because coupling capacitors, like Cc2, are treated as shorts at AC frequencies. Consequently, any changes in collector current (IC) due to input signal (isig) affect both resistors simultaneously. This parallel configuration simplifies the calculation of output voltage (Vo) in response to AC signals. Understanding this concept is crucial for accurate AC analysis in amplifier design.
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Can someone please explain to me with what reasoning RL and RC are taken to be in parallel when calculating Vo for any decrease/increase in IC (DC) due to isig (ac)

Thank you
 

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In AC analysis there should be a very low impedance between ground and Vcc. Likewise Cc2 is assumed to be a short, thus RL and Rc are in parallel.
 

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