Jul 3, 2012 #1 G guruteja Newbie level 2 Joined Jul 3, 2012 Messages 2 Helped 0 Reputation 0 Reaction score 0 Trophy points 1,281 Activity points 1,296 Why the input impedance is more for CE configuration transistor?
Jul 3, 2012 #2 N nm2007k Member level 1 Joined Oct 20, 2010 Messages 40 Helped 1 Reputation 2 Reaction score 1 Trophy points 1,288 Location Tamilnadu,INDIA Activity points 1,545 Input impedance is higher for CC configuration only.
Jul 3, 2012 #3 LvW Advanced Member level 6 Joined May 7, 2008 Messages 5,912 Helped 1,753 Reputation 3,512 Reaction score 1,364 Trophy points 1,393 Location Germany Activity points 40,432 guruteja said: Why the input impedance is more for CE configuration transistor? Click to expand... More than what? Such a formulation always needs a comparison between two alternatives.
guruteja said: Why the input impedance is more for CE configuration transistor? Click to expand... More than what? Such a formulation always needs a comparison between two alternatives.
Jul 3, 2012 #4 Baas Rietrot Member level 5 Joined Jun 19, 2012 Messages 92 Helped 15 Reputation 30 Reaction score 15 Trophy points 1,298 Location South Africa Activity points 1,711 The CE amplifier will only have a high input impedance if you insert a degeneration resistor (RE), not-bypassed. Thus, input impedance with bias resistors (R1 & R2) added: \[R_{i} = R_{1}||R_{2}||(r_{\pi}+(\beta+1)R_{E})\] Without or bypassed RE: \[R_{i} = R_{1}||R_{2}||r_{\pi}\] The equations can be derived from your small signal analysis.
The CE amplifier will only have a high input impedance if you insert a degeneration resistor (RE), not-bypassed. Thus, input impedance with bias resistors (R1 & R2) added: \[R_{i} = R_{1}||R_{2}||(r_{\pi}+(\beta+1)R_{E})\] Without or bypassed RE: \[R_{i} = R_{1}||R_{2}||r_{\pi}\] The equations can be derived from your small signal analysis.