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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.
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The Common-Collector Amplifier Input and Output Resistance – The Proof
Monday, October 12th, 2009Summary:
In this article I will show a method to deduce the input and output resistance of the common collector amplifier. The common-collector amplifier is a well known circuit (see Figure 1). It is mostly used as a buffer due to its high input resistance, small output resistance and unity gain buffer. The equations derived in this article are symbolic, as is the derivation of any other formula in this website. Still, even if the resistances’ values are not numeric, the equations are intuitive enough to show the high input low output resistance property of the amplifier.
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Derive the Transfer Function of the Common Collector Amplifier with Thevenin’s Theorem
Sunday, October 4th, 2009Summary:
How to Apply Thevenin’s Theorem for Solving Circuits with Dependent Sources.
Besides its use to simplify and calculate currents in electrical circuits, Thevenin’s Theorem is also a great tool that we can use to derive transfer functions. This article will illustrate how to derive the small signal transfer function of the Common-Collector Amplifier with bipolar junction transistors (BJTs).
The circuit is shown in Figure 1. It is also called a repeater, so we expect that the calculated transfer function to be close to unity gain.
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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.
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How to Derive the Non-Inverting Amplifier Transfer Function
Saturday, August 29th, 2009Summary:
One of the most common amplifiers in Analog Design is the non-inverting amplifier. How do you derive its transfer function?
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Useful Operational Amplifier Formulas and Configurations
Sunday, August 23rd, 2009Summary:
A compilation of Op Amp configurations and transfer functions.
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The Transfer Function of the Non-Inverting Summing Amplifier with “N” Input Signals
Sunday, August 9th, 2009Summary:
In a previous article, How to Derive the Summing Amplifier Transfer Function, I deduced the formula for the non-inverting summing amplifier with two signals in its input. But what if we have 3, 4 or an n number of signals? Can we add them all with one amplifier?
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