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Bipolar to Unipolar Converters Based on a Summing Amplifier Configuration
Monday, December 28th, 2009Summary:
In a previous article I presented a method for designing a bipolar to unipolar converter using a summing amplifier. In this article I am going to show more examples of bipolar to unipolar converters which are based on a summing amplifier configuration. You can adapt them to your needs if you use the method I described in the previous article.
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The Non-Inverting Amplifier Output Resistance
Wednesday, December 23rd, 2009Summary:
It is customary to consider the output resistance of the non-inverting amplifier as being zero, but why is that? An Op Amp’s own output resistance is in the range of tens of ohms. Still, when we connect the Op Amp in a feedback configuration, the output resistance decreases dramatically. Why?
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How to Derive the Inverting Amplifier Transfer Function
Thursday, November 26th, 2009Summary:
Widely used in Analog Design, the inverting amplifier in Figure 1 has a simple transfer function. What is the proof of this function?
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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.
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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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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.
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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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