Comments on: Solving the Differential Amplifier – Part 2 http://masteringelectronicsdesign.com/solving-the-differential-amplifier-part-2/ Electronics Design and Modeling with Emphasis on Analog Design Wed, 21 Jul 2010 05:50:16 +0000 http://wordpress.org/?v=2.9 hourly 1 By: KrisBelucci http://masteringelectronicsdesign.com/solving-the-differential-amplifier-part-2/#comment-21 KrisBelucci Tue, 02 Jun 2009 16:03:03 +0000 http://masteringelectronicsdesign.com/?p=105#comment-21 Great post! Just wanted to let you know you have a new subscriber- me! Great post! Just wanted to let you know you have a new subscriber- me!

]]> By: senti32 http://masteringelectronicsdesign.com/solving-the-differential-amplifier-part-2/#comment-11 senti32 Sat, 02 May 2009 15:12:11 +0000 http://masteringelectronicsdesign.com/?p=105#comment-11 no, i power the opamp 0 to 5V. the source is 0.5V peak to peak and i need the output to be 1.5V peak to peak. no, i power the opamp 0 to 5V. the source is 0.5V peak to peak and i need the output to be 1.5V peak to peak.

]]> By: Adrian S. Nastase http://masteringelectronicsdesign.com/solving-the-differential-amplifier-part-2/#comment-12 Adrian S. Nastase Sat, 02 May 2009 14:52:32 +0000 http://masteringelectronicsdesign.com/?p=105#comment-12 In this case you need to bias the input so that the output is somewhere in the middle of 0 to 5V. You did not mention what is the DC level at the OpAmp's output, but let's assume it has to be exactly in the middle, at 2.5V. Connect the source at V1, connect R3 to ground and connect R2 to a DC level of 2.5V. If you decrease the input signal down to zero, you will see that the OpAmp output is 2.5V. As you increase the AC level, the output signal rides on top of 2.5V. Choose R1, R2, R3, R4 so that R4/R1 = R2/R1 = 3, your gain. In this case you need to bias the input so that the output is somewhere in the middle of 0 to 5V. You did not mention what is the DC level at the OpAmp’s output, but let’s assume it has to be exactly in the middle, at 2.5V.

Connect the source at V1, connect R3 to ground and connect R2 to a DC level of 2.5V. If you decrease the input signal down to zero, you will see that the OpAmp output is 2.5V. As you increase the AC level, the output signal rides on top of 2.5V.

Choose R1, R2, R3, R4 so that R4/R1 = R2/R1 = 3, your gain.

]]> By: senti32 http://masteringelectronicsdesign.com/solving-the-differential-amplifier-part-2/#comment-9 senti32 Sat, 02 May 2009 07:28:45 +0000 http://masteringelectronicsdesign.com/?p=105#comment-9 thank you very much for explaining the differential amplifier. i have a question: i need to connect between v1 and v2 a AC source. is there a easy way to find the resistors for a given output range? thank you very much for explaining the differential amplifier. i have a question: i need to connect between v1 and v2 a AC source. is there a easy way to find the resistors for a given output range?

]]> By: Adrian S. Nastase http://masteringelectronicsdesign.com/solving-the-differential-amplifier-part-2/#comment-10 Adrian S. Nastase Sat, 02 May 2009 05:56:17 +0000 http://masteringelectronicsdesign.com/?p=105#comment-10 If your OpAmp has a bipolar source (+/- 12 V as an example) you can connect the AC source directly to V1 V2 inputs. Make R4/R3 = R2/R1 and equal with the gain you need. Chances are your source does not float and has a ground connection. Connect its output at V1 and connect R3 to ground. This is a classic way to design a non-inverting amplifier with the gain less than 1. Otherwise, if your gain is greater than 1, you can eliminate R1 and R2, connect the output of your source to the non-inverting input of U1 and connect R3 to ground. The gain will be 1+R4/R3. If your OpAmp has a bipolar source (+/- 12 V as an example) you can connect the AC source directly to V1 V2 inputs. Make R4/R3 = R2/R1 and equal with the gain you need. Chances are your source does not float and has a ground connection. Connect its output at V1 and connect R3 to ground. This is a classic way to design a non-inverting amplifier with the gain less than 1. Otherwise, if your gain is greater than 1, you can eliminate R1 and R2, connect the output of your source to the non-inverting input of U1 and connect R3 to ground. The gain will be 1+R4/R3.

]]>