So how do we actually measure these voltages at the most basic level, voltage is measured using a circuit
that's known as an analog to digital converter.
This technology has a number of commonly seen abbreviations, such as ADC or D or a 2D or 2D spelled
out and analog to digital converter samples, the voltage level that its input.
And it converts that voltage level into a binary pattern of ones and zeros inside of a special purpose
integrated circuit or inside of a microcontroller having a built-In ADC.
The binary pattern is a digital representation of the voltage that it's measuring.
There are several common analog to digital conversion architectures.
One is known as a direct conversion on a flash technology electronically.
This converter uses a bank of comparator circuits that detect whether the input voltage is above or
below some internally regulated fixed voltage.
So overall, this collection of competitors is used to determine and output the code corresponding to
the voltage that's closest to any one of these comparator circuits.
This technology is the fastest of all the ADC methods and it's essentially instantaneous.
But it's also the most expensive to implement because of the number of competitors and the number of
fixed reference voltages that must be built inside of the converter.
The second method for analog to digital conversion relies internally on really the opposite technology
a digital to analog converter.
It turns out that it's relatively simple to build a digital to analog converter using some common components,
some resistors and an operational amplifier.
There may be better approaches than that, but the main point is that it's simple to build a digital
to analog controller, whereas it's more complicated to build an analog to digital converter.
So the second analog to digital conversion approach guesses at what the voltage might be and then outputs
a voltage corresponding to that gas using its digital to analog converter.
It then uses a single competitor to see whether the voltage produced by the gas is above or below the
voltage at the input that it's trying to measure.
And by successive approximation, it keeps on this higher, lower guessing until it gets close enough
to an estimate of the voltage it's trying to measure.
This is a somewhat slow approach because of the need to repeatedly make these guesses, but it's also
a very inexpensive approach to implement.
The third approach is relatively modern and is adopted in many, many applications.
It's known as a sigma delta or sometimes as a Delta Sigma approach.
The method is somewhat similar to the successive approximation approach in that it guesses what the
voltage is and produces a voltage at its output corresponding to that gas.
And then it uses a one bit flash analog to digital converter, which requires only a single competitor
to encode the difference between the approximation and the input it's trying to measure.
Usually the Delta Sigma approach uses very fast sampling in order to come up with some differences of
the one with ADC in order to very quickly approximate the input signal.
So it's successively approximates using a flash ADC at a very fast sample rate, and it's a very popular
approach regardless of the method used for ADC.
Each of these is usually implemented in a specialized integrated circuit or icey because of the need
to precisely match all of the resistances and capacitance and all of the components involved in making
the circuit.
And it's easier to match these components on side of an integrated circuit than it is using discrete
components and an externally built circuit.
It's also common practice to include analog to digital converters built into many microcontrollers.
So battery management systems for small battery packs may not need any external circuitry outside the
microcontroller itself for voltage measurement.