Comments on: The Common-Collector Amplifier Input and Output Resistance – The Proof http://MasteringElectronicsDesign.com/the-common-collector-amplifier-input-and-output-resistance/ Electronics Design and Modeling with Emphasis on Analog Design Wed, 02 May 2012 09:00:29 +0000 http://wordpress.org/?v=2.9 hourly 1 By: Adrian S. Nastase http://MasteringElectronicsDesign.com/the-common-collector-amplifier-input-and-output-resistance/#comment-4038 Adrian S. Nastase Wed, 14 Sep 2011 07:13:12 +0000 http://masteringelectronicsdesign.com/?p=814#comment-4038 Yes, it will come soon. Keep an eye on MasteringElectronicsDesign.com. Thank you for visiting. Yes, it will come soon. Keep an eye on MasteringElectronicsDesign.com. Thank you for visiting.

]]> By: Matthew http://MasteringElectronicsDesign.com/the-common-collector-amplifier-input-and-output-resistance/#comment-4033 Matthew Tue, 13 Sep 2011 20:16:24 +0000 http://masteringelectronicsdesign.com/?p=814#comment-4033 How about the same type of analysis for the common-base amplifier please? How about the same type of analysis for the common-base amplifier please?

]]> By: doug http://MasteringElectronicsDesign.com/the-common-collector-amplifier-input-and-output-resistance/#comment-3205 doug Thu, 10 Mar 2011 09:09:35 +0000 http://masteringelectronicsdesign.com/?p=814#comment-3205 thank you for your reply, and apologies for the earlier typos, as you say, stray capacitances are proving to be a major consideration, ive noticed even on fairly low frequencies, a few hundred kilohertz or so, and with even a 555 on a good layout, im getting a residual capacitance of around 15 p to 20 p on the timing elements. thanks again dougal thank you for your reply, and apologies for the earlier typos,
as you say, stray capacitances are proving to be a major consideration, ive noticed even on fairly low frequencies, a few hundred kilohertz or so, and with even a 555 on a good layout, im getting a residual capacitance of around 15 p to 20 p on the timing elements.

thanks again
dougal

]]> By: Adrian S. Nastase http://MasteringElectronicsDesign.com/the-common-collector-amplifier-input-and-output-resistance/#comment-3202 Adrian S. Nastase Thu, 10 Mar 2011 01:31:15 +0000 http://masteringelectronicsdesign.com/?p=814#comment-3202 Yes, although, for high frequency applications, I would add the transistor parasitic capacitances in this hybrid-pi model. At minimum, add C-pi in parallel with r-pi and the feedback capacitance C-miu. Yes, although, for high frequency applications, I would add the transistor parasitic capacitances in this hybrid-pi model. At minimum, add C-pi in parallel with r-pi and the feedback capacitance C-miu.

]]> By: doug http://MasteringElectronicsDesign.com/the-common-collector-amplifier-input-and-output-resistance/#comment-3199 doug Wed, 09 Mar 2011 12:55:30 +0000 http://masteringelectronicsdesign.com/?p=814#comment-3199 hi great tutoriol i'm matching a simple banpass to a colpits .is transistor output resistance the same as output impedance? hi

great tutoriol

i’m matching a simple banpass to a colpits .is transistor output resistance the same as output impedance?

]]> By: Adrian S. Nastase http://MasteringElectronicsDesign.com/the-common-collector-amplifier-input-and-output-resistance/#comment-2994 Adrian S. Nastase Fri, 11 Feb 2011 22:20:20 +0000 http://masteringelectronicsdesign.com/?p=814#comment-2994 Ron, thank you for your comment.  I introduced the source load in calculations for 2 reasons.  1.  Consistency.  Whenever we study the input and output resistance of a network, it is advised by many to always take into consideration the source resistance.  This resistance may, or may not, influence the result.  In this case, the source resistance does not have any influence on the input resistance.  Instead of cherry-picking when to introduce the source resistance and when not, and confuse the readers in the process, better have it in any system study.  Readers can easily see that it adds to r-pi and can ignore it if they choose so. 2. Signal accuracy.  As figure 3 shows, the calculation of the input resistance is correct, as it is done from the ideal source point of view, through its own resistance.  When we look at a stage output signal level, it is actually the level before its own output resistance.  This level can be affected by the attenuation created by the source resistance and the input resistance of the following stage.  In the case of the common-collector amplifier, the source resistance helps, as it adds to the transistor input resistance.  So, yes, you are right.  The source resistance is not part of the transistor input resistance per see.  In my opinion it should be there for the reasons I stated. Ron, thank you for your comment.  I introduced the source load in calculations for 2 reasons. 

1.  Consistency.  Whenever we study the input and output resistance of a network, it is advised by many to always take into consideration the source resistance.  This resistance may, or may not, influence the result.  In this case, the source resistance does not have any influence on the input resistance.  Instead of cherry-picking when to introduce the source resistance and when not, and confuse the readers in the process, better have it in any system study.  Readers can easily see that it adds to r-pi and can ignore it if they choose so.

2. Signal accuracy.  As figure 3 shows, the calculation of the input resistance is correct, as it is done from the ideal source point of view, through its own resistance.  When we look at a stage output signal level, it is actually the level before its own output resistance.  This level can be affected by the attenuation created by the source resistance and the input resistance of the following stage.  In the case of the common-collector amplifier, the source resistance helps, as it adds to the transistor input resistance. 

So, yes, you are right.  The source resistance is not part of the transistor input resistance per see.  In my opinion it should be there for the reasons I stated.

]]> By: Ron Harrison http://MasteringElectronicsDesign.com/the-common-collector-amplifier-input-and-output-resistance/#comment-2986 Ron Harrison Fri, 11 Feb 2011 04:31:56 +0000 http://masteringelectronicsdesign.com/?p=814#comment-2986 I understand why you include source resistance in the output resistance equation, but why do you have it in the equation for input resistance? The source resistance is independent of the transistor. The transistor's input resistance is the load on the source resistance. I understand why you include source resistance in the output resistance equation, but why do you have it in the equation for input resistance? The source resistance is independent of the transistor. The transistor’s input resistance is the load on the source resistance.

]]> By: stephen datsomor http://MasteringElectronicsDesign.com/the-common-collector-amplifier-input-and-output-resistance/#comment-1031 stephen datsomor Sun, 13 Jun 2010 11:51:21 +0000 http://masteringelectronicsdesign.com/?p=814#comment-1031 this allowed me have an understanding of how to derive the input and output resistance this allowed me have an understanding of how to derive the input and output resistance

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