The lock-in amplifier allows tiny signals from sensors to be captured with precision despite unavoidable noise limitations and other test and measurement challenges of the signal chain. Part 1 of this article looked at the changes of capturing low-level signals such as from a photodetector despite unavoidable signal-path noise, drift, offsets, and other imperfections. This […]
FAQ
Understanding the lock-in amplifier, Part 1: The sensing challenge
The lock-in amplifier allows tiny signals from sensors to be captured with precision despite unavoidable noise limitations and other signal-chain test and measurement challenges. There are some basic test and measurement instruments common to scientific labs and engineering benches of all types, whether electronic, biomedical, chemical, optical, or mechanical. Among these are the digital voltmeter, […]
Sigma Delta ADC vs. SAR vs. Pipeline: How to Choose
Assuming that you are familiar with the fundamental specifications of an ADC and what they mean, the next step is to know your entire signal chain well and then work to fit the ADC to the requirements. After carefully determining signal chain requirements, then select your ADC with the understanding that if the ADC is […]
Reducing ringing or reflections by controlling impedance lines
What is a controlled impedance line? For one thing, the term has to do with Printed Circuit Board (PCB) traces and layouts, which get more complex with higher frequency signals. Generally, you need not worry much about controlling impedance in traces unless you are working with signals at or above 50 MHz. However, most of […]
Understanding Radio Frequency communications
Wireless communication has been around since the 18th century when James Clerk Maxwell first proposed that electromagnetic waves can be generated and can travel through free space. Heinrich Rudolf Hertz conducted the experiments in which he demonstrated the generation, transmission, and reception of electromagnetic waves, which became the basis of Radio Frequency communication. Wireless communication […]
Stress & Strain, Part 2: Implications for electronics
The mechanical strain induced on electronic components due to mechanical and thermal stress is an important aspect of their performance consistency and limitations; stress is also used to enable some materials to provide critical electronic functions. Part 1 of this FAQ looked at the basic principles and tests for material strain when stress is applied. […]
Stress & Strain, Part 1: Fundamental principles
The mechanical strain induced on electronic components due to mechanical and thermal stress is an important aspect of their performance consistency and limitations; stress is also used to enable some materials provide critical electronic functions. Although electronic systems and circuits invoke intangibles such as voltages, currents, power, EM fields, and Maxwell’s equations — to cite […]
Improving transimpedance amplifiers with a bootstrap
Analog bootstrap circuits are traditionally ones where output is fed back to the input, usually to increase input impedance. This can be to minimize either the resistive or reactive (usually capacitive) components of the input impedance or both. The term is now also used with MOSFET drivers where a capacitor is charged and used to […]
Input bias current cancellation in bipolar op amps
Bipolar operational amplifiers have an essential input bias current requirement. This bias current has to come from somewhere and can be a nuisance in some types of high impedance circuits such as charge amplifiers and transimpedance amplifiers and can result in offset voltages where input resistances aren’t matched. The example shown below has an input […]
A comparison of EMI test setups and specifications for automotive, industrial and defense applications, part 2: Radiated emissions
By Timothy Hegarty, Applications Engineer, Texas Instruments This article compares electromagnetic compatibility (EMC) requirements in automotive, industrial and defense product family standards, specifically various test parameters, test equipment, test setups and test methods for radiated emissions (REs). Much like the treatment of conducted emissions [1] in part 1 of this two-part article series, the comparison […]
