| « Previous | Next » |
Design a Differential Amplifier the Easy Way with Mathcad
Thursday, November 19th, 2009Summary:
For those of you who have Mathcad, designing a differential amplifier is really easy.
Let’s say you need to design a unipolar to bipolar converter and you decide to use a differential amplifier for this task. You know the input and output voltage range and you need to calculate the resistors based on a voltage reference you have in the system. All you have to do is to create a Mathcad file for a quick response. Then store it some place for future designs.
Design a Unipolar to Bipolar Converter for a Unipolar Voltage Output DAC
Monday, November 2nd, 2009Summary:
Unipolar to bipolar converters are useful when we have to have a unipolar component to do a certain job in a mixed signal design environment. For example, Digital to Analog Converters (DACs) may have the output voltage range 0 to 2.5 V, or 0 to 5 V, while the design asks for a range of –5 V to +5 V. To comply with this requirement, we have to design a unipolar to bipolar converter which will be inserted between the DAC output and the following bipolar stage.
Design a Bipolar to Unipolar Converter to Drive an ADC
Monday, October 26th, 2009Summary:
Most ADCs have a unipolar input range that can be a problem when designing bipolar circuits. Some common ADC input voltage ranges are 0 to 2.5 V, or 0 to 5 V. However, the analog circuit that drives the ADC can have voltage swings of, –1 V to +1 V, –2 V to +2 V , –5 V to +5 V, and so on. Bringing the ADC input below ground is a big No-No, because the current from input will flow through the chip substrate creating irreversible changes in the ADC and damage it. So, how do we connect a bipolar front end circuit with a unipolar ADC? Enters the bipolar to unipolar converter. Let’s design one.
Summary:
What is this circuit good for? It creates a single-ended-input-differential-output amplifier, in which VCM is the common mode and the main signal, in this case the average (VA+VB)/2 rides on top of VCM. It is very useful for fully differential circuits in low noise applications, because differential amplifiers help reduce the common mode noise. VCM in this case, sets the common mode to a useful level as required by the design.
The Transfer Function of an Amplifier with a Bridge in the Negative Feedback
Friday, July 3rd, 2009Summary:
In allaboutcircuits.com forum an interesting circuit was posted. The question was, how to determine the transfer function, Vout/Vin?
The circuit schematic was drawn as in Figure 1.
Solving the Differential Amplifier – Part 2
Friday, May 1st, 2009Summary:
But the resistors’ calculation becomes a bit of a challenge, when one might be faced with designing a differential amplifier with a certain transfer function. The example I took in the first article was as follows: Given an input range of, -0.5V to 5.5V, the output has to swing between, -1.25V and +2.365V. I solved the problem by using the amplifier transfer function and a system of equations.
In this article I am going to write about designing the resistors of this differential amplifier using the method of coefficients identification.
Starting from the differential amplifier transfer function …
Injecting AC into the DC Power Supply Rail
Monday, April 27th, 2009Summary:
In allaboutcircuits.com forum, a question was posted: How can I combine an AC source of known frequency and amplitude with a DC power supply?
I thought this is an interesting problem, so here is the solution.
| « Previous | Next » |
