Comments on: The Differential Amplifier Common-Mode Error – Part 2 https://masteringelectronicsdesign.com/the-differential-amplifier-common-mode-error-part-2/ Electronics Design and Modeling with Emphasis on Analog Design Thu, 19 May 2016 04:18:10 +0000 hourly 1 By: Adrian S. Nastase https://masteringelectronicsdesign.com/the-differential-amplifier-common-mode-error-part-2/#comment-35433 Thu, 19 May 2016 04:18:10 +0000 http://masteringelectronicsdesign.com/?p=300#comment-35433 In reply to Ricky.

Why negative 2? If R2/R1 = R4/R3 = 2, then equation (6) becomes:

Gcm = 2*(1+2)/(1+2) – 2 = 0

]]> By: Ricky https://masteringelectronicsdesign.com/the-differential-amplifier-common-mode-error-part-2/#comment-35378 Mon, 16 May 2016 13:42:00 +0000 http://masteringelectronicsdesign.com/?p=300#comment-35378 Sorry, i dont get the part when Gcm = 0 when the ratio is the same. If i take R2/R1 = R4/R3 = 2. Then shouldnt the equation come out to be -2?

]]> By: Adrian S. Nastase https://masteringelectronicsdesign.com/the-differential-amplifier-common-mode-error-part-2/#comment-16700 Mon, 14 Oct 2013 16:46:36 +0000 http://masteringelectronicsdesign.com/?p=300#comment-16700 In reply to eddy.

I sent you a message using the email address you gave me. Send the schematic in response.

]]> By: eddy https://masteringelectronicsdesign.com/the-differential-amplifier-common-mode-error-part-2/#comment-16697 Sun, 13 Oct 2013 16:59:41 +0000 http://masteringelectronicsdesign.com/?p=300#comment-16697 In reply to Adrian S. Nastase.

How do I sent the file using the contact page? Thanks

]]> By: Adrian S. Nastase https://masteringelectronicsdesign.com/the-differential-amplifier-common-mode-error-part-2/#comment-16692 Sat, 12 Oct 2013 20:24:55 +0000 http://masteringelectronicsdesign.com/?p=300#comment-16692 In reply to eddy.

I need to see a schematic to help you. You say that V2 = 0…2.75 and later on you say that V2 can only go to max 1.85V. Which one is which? To send me a schematic use my contact page
http://masteringelectronicsdesign.com/contact-page/
and I will reply with my email address.

]]> By: eddy https://masteringelectronicsdesign.com/the-differential-amplifier-common-mode-error-part-2/#comment-16691 Sat, 12 Oct 2013 01:04:21 +0000 http://masteringelectronicsdesign.com/?p=300#comment-16691 I need some help with the differential amplifier. I have a differential amp circuit with Vin of V1=0.55V and V2=0….2.75 with resistor ratio of 2.2727272. This will give the variation of Vout= 0….5V. The Vout acted as Vref to control the BLDC motor (driver). When I connected this circuit with load (BLDC motor+driver), the Vout drop to 2.95V (the max V2 can go is 1.85V). I was wondering what should I add to the circuit to make sure it does not occur any voltage drop? Is the transient diode will do the job? Thank you.

]]> By: Adrian S. Nastase https://masteringelectronicsdesign.com/the-differential-amplifier-common-mode-error-part-2/#comment-2767 Fri, 15 Oct 2010 06:01:40 +0000 http://masteringelectronicsdesign.com/?p=300#comment-2767 In reply to micheal.

An ideal differential amplifier can be represented by an ideal dependent voltage source. It is dependent, because its value is given by the product between the differential input voltage and the amplifier gain. So, here you go, you have a voltage source connected to a load (you say loaded amplifier) and this voltage source is probably part of a circuit. Then you can apply Thevenin’s Theorem to solve the circuit.

If you need more details, you need to tell me more. Maybe send me a schematic?

]]> By: micheal https://masteringelectronicsdesign.com/the-differential-amplifier-common-mode-error-part-2/#comment-1769 Thu, 07 Oct 2010 18:20:33 +0000 http://masteringelectronicsdesign.com/?p=300#comment-1769 how can thevinin theory be applied to loaded differential amplifier. pls. i need a comment on that.

]]> By: oleg23 https://masteringelectronicsdesign.com/the-differential-amplifier-common-mode-error-part-2/#comment-1051 Thu, 17 Jun 2010 05:22:19 +0000 http://masteringelectronicsdesign.com/?p=300#comment-1051 i found a link to this article in electro-tech-online.com forum. great article, very clear. please keep up the good work.

]]> By: Nynelly https://masteringelectronicsdesign.com/the-differential-amplifier-common-mode-error-part-2/#comment-272 Sun, 04 Oct 2009 09:28:27 +0000 http://masteringelectronicsdesign.com/?p=300#comment-272 best new blog

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