A logarithmic resistor ladder consists of a resistor string and switches designed to attenuate a signal. The state of the switches can be considered to represent a digital code proportional to the logarithm of the attenuation ratio. Logarithmic attenuation is useful when a large dynamic range is needed. Audio volume control and fading/balancing audio signals […]
FAQ
Where do you use A, B, AB, D, G, DG and H circuits?
This selection of power amplifier classes is used to strengthen AC signals. The letter symbols differentiate between amplifier types and indicate the expected performance and characteristics. Basic amplifier classes such as A, B, AB, and C relate to the time that the amplifier is operating, or conducting, expressed as a fraction of the period of […]
Teardown: Inside an industrial absolute encoder
If you go to the Wikipedia page on absolute encoders, you’ll find descriptions of these devices mentioning multiple code rings, glass or plastic discs, and configurations of sliding contacts arranged so each contact wipes against a metal disc at a different distance from a turning shaft. Actually, you’d be hard pressed to find any of […]
What causes noise in analog designs and how can it be controlled?
Controlling noise in analog and mixed-signal circuits is important but not simple. Data integrity is dependent on controlling noise in the signal chain. If left uncontrolled, noise can impair or disrupt system operation. This FAQ starts by looking at the various sources and types of noise, looks at how noise can enter the signal chain […]
How big is the band gap? A heated discussion
There’s a trick with a soldering iron can be used to determine whether an unidentified semiconductor is n-type or p-type. In essence, it determines whether the majority carriers are holes (p-type) or electrons (n-type). Just as heat makes a gas expand (PV=nRT), the hot tip of a soldering iron makes carriers expand away from the […]
Five considerations for mixed-signal PCB layouts
Printed circuit board (PCB) layout is an important activity when developing mixed-signal applications. A lot can go wrong, and everything needs to be correct for a successful design. Impedance control is an obvious consideration, but it needs to include trace resistance as well as parasitic inductances and capacitances. Maintaining signal integrity can be challenging. This […]
Smart buildings and the IoT: Zoning systems
There are significant benefits to moving some decisions in smart HVAC systems close to the application and away from the cloud. Asem Elshimi, Silicon Labs We’ve probably all experienced an office environment that always felt too cold or hot no matter the weather. And we’ve all experienced the fruitlessness of asking the building facilities team […]
When is a high CMRR needed in an op amp?
Common mode rejection ratio (CMRR), also called common mode rejection (CMR), quantifies the ability of an operational amplifier (op amp) to reject common-mode signals. Common-mode signals are signals that appear simultaneously and in phase on both inputs. This FAQ begins by defining what CMRR is and how it’s quantified, reviews some design considerations related to […]
Long-life batteries harness the passivation effect
A little known chemical reaction helps extend battery life. Sol Jacobs, Tadiran Batteries As remote wireless devices become increasingly essential to the Industrial Internet of Things (IIoT), there is a growing need to understand the principles behind extended battery life. Many IIoT nodes require a battery-driven energy source. These off-grid low-power applications fall into two […]
The difference between signal under-sampling, aliasing, and folding
Most engineers today are sensitive to problems that arise when digital measurement instruments try to capture signals containing frequencies that are too high for the sampling circuitry to handle–undergrad EE programs typically cover Nyquist’s sampling theorem. Nevertheless, there are terms associated with sampling problems that sometimes get confused. Probably the three concepts most likely to […]
