- #1
etf
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Hi!
My task is to calculate input resistance for circuit below:
VDD=10V, Vtn=1V, β=1mA/V^2, VA=100V, load resistance RL=20k.
Here is model for AC analysis (DC source and infinite capacitances are short circuits, current directions chosen arbitrarily):
After calculationg input current iin, I found input resistance Rin=vin/iin=1/((1/RL+1/RD)*(1/rds+gm)/(1/RL+1/RD+1/rds)+1/Rs).
Here is solution from my book: Rin=(rds+RD)*RS/(rds+RD+(1+gm*rds)*RS). I double checked my result and it's correct.I simulated circuit in Multisim and value for input resistance I got matches with value I got by hand. What's wrong? Any idea? :)
My task is to calculate input resistance for circuit below:
VDD=10V, Vtn=1V, β=1mA/V^2, VA=100V, load resistance RL=20k.
Here is model for AC analysis (DC source and infinite capacitances are short circuits, current directions chosen arbitrarily):
After calculationg input current iin, I found input resistance Rin=vin/iin=1/((1/RL+1/RD)*(1/rds+gm)/(1/RL+1/RD+1/rds)+1/Rs).
Here is solution from my book: Rin=(rds+RD)*RS/(rds+RD+(1+gm*rds)*RS). I double checked my result and it's correct.I simulated circuit in Multisim and value for input resistance I got matches with value I got by hand. What's wrong? Any idea? :)
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