Digital-to-analog converters (DACs) are subject to gain and offset error. Errors can be compensated for with hardware by using external components or by trimming the DACs after they have been manufactured. Trimming is necessary because the error is caused by mismatched resistors; trimming attempts to change resistor values in the DAC. However, some DACs can […]
FAQ
Monotonicity: What is it and why is it important?
There are many parameters which define the performance of analog and mixed-signal circuits. Among the many “static” (sometimes called “DC” specifications, but this is a misnomer) factors are offset error, gain error, integral nonlinearity, and differential nonlinearity. Note that there are also dynamic specifications (called “AC” specifications but also a misnomer) such as the effective […]
Why use a nonlinear amp?
Users normally place a great deal of value in the high linearity of an amplifier and its corresponding low distortion. Audio amplifiers, for example, are quoted with many linearity specifications, such as total harmonic distortion (THD) or 1%, 0.1% or even less. Even the outputs of amplifiers with internal topologies which are inherently nonlinear, such […]
What is a multiplying DAC?
Multiplying digital-to-analog converters (MDACs) produce a (current) output signal that’s a product of the given reference voltage and the code (i.e., a string of 0s and 1s) flowing through it. All data converters require a voltage reference (VREF) and a typical, standard DAC needs a very stable fixed reference voltage in order to operate properly. […]
Optocoupler selection and usage for isolating a PWM
An optocoupler (or optoisolator) is a device that galvanically separates circuits and is not only great at isolation but allows you to interface to circuits with different ground planes or that operate at different voltage levels. Optocouplers are “fail safe” in that if subjected to voltages higher than the maximum rating, they are known to […]
What does an analog driver/buffer do?
The term “buffer” has many definitions in electronics hardware and software. It can be a reserved software area where data is temporarily stored until it is processes; a set of internal IC registers where data is queued before being transmitted or after it has been received; or it can be a circuit function interposed to […]
Basics of bandpass filters
Filters will allow some signals to pass through while blocking others. A bandpass (a.k.a. band-pass) filter allows signals of a certain frequency range (“a band of frequencies”) to pass through the filter as-is. (This range of accepted frequencies is called the passband. The size or range of the passband is called the bandwidth.) With a […]
Making sense of thermocouples and interfaces: part 2
Part 1 of this FAQ looked at the basics of thermocouples, where and why they are used, and some basic implementation issues; this part explores interface issues, cold junction compensation, and linearization. What are the requirements for thermocouple interface electronics? The thermocouple voltage is relatively small, so long leads between the thermocouple and the electronic front-end […]
Unity gain amplifier or voltage follower in a voltage divider
A voltage follower is also known as a unity gain amplifier, a voltage buffer, or an isolation amplifier. In a voltage follower circuit, the output voltage is equal to the input voltage; thus, it has a gain of one (unity) and does not amplify the incoming signal. The voltage follower does not need any external […]
Passive sensors and active sensors: What are they?
“Passives” in general within the electronics community are devices that do not drive or transmit power or signals. Passive Sensors do not control electricity directly and do not require external power sources to accomplish control of an electrical signal. Examples of passive components are resistors (R), capacitors (C), inductors (L), transformers, antennas, potentiometers (variable resistors), […]
