System designers of industrial data acquisition cards face significant challenges in meeting their customers’ stringent demands for accuracy, noise, speed, and reliable operation in a harsh environment. I recently wrote an article in the April, 2013 edition of Analog Dialogue on the PLC analog input module that emphasizes how the versatile, low cost, and highly integrated ADAS3022 takes the additional burden off from the system designers’ shoulders and solves the challenges of typical discrete multichannel data acquisition system components by eliminating analog front-end (AFE) stages, resulting in reduced cost and faster time to market while offering true 16-bit precision performance at 1MSPS in an easy-to-use small form factor.

Find out more about this article on Analog Dialogue, Complete Sensor-to-Bits Solution Simplifies Industrial Data-Acquisition System Design.

Learn more information on the ADAS3022.

Find out more about Process Control and Industrial Automation solutions from ADI.

I would like to hear any feedback or comments on this article or this topic in general. You can leave your feedback in the comment section below.

Best Regards,

Maithil

The current that an LED luminaire is driven at is one of the most important decisions of the entire product design.  Sometimes, lighting designers find that the cost of the system can be reduced by driving LEDs at higher currents (though never exceeding the LED datasheet, of course).  And new LEDs are pushing this as high as 4A.  Many of the LED drivers are buck regulators (the inductor of the buck's output stage looks like a current source to the LED, so it is a natural choice).  And while there are lots (and lots) of high current buck regulators, very few of them are for controlling LED current at >1A.  The few that do are often expensive and really not that feature rich.  So why not take a high efficiency buck regulator and convert it into a super smart LED driver? 

In this month's Analog Dialogue I offer some tips, tricks and examples for doing exactly that.  The article looks at accurately controlling the LED current with maximum efficiency, various fault modes and protections for the LEDs, and implementing some popular dimming methods (PWM, analog, and thermal).  You can read the article here:

Convert a Buck Regulator into a Smart LED Driver, Including Dimming

I would love to hear any feedback, comments, or questions.  Have you done or seen something like this before?  How did it turn out?  What features matter most to you (and which do you think are just marketing fluff)?  What are some issues remaining to be solved in this system? 

Also, more information and products can be found on our newly launched microsite:  www.analog.com/lighting

Best Regards,

  - Jon

Recently I wrote an article which appeared in the Volume 47 - February 2013 edition of Analog Dialogue. This article outlines a method of estimating the noise introduced into an ADC signal chain by an amplifier or driver. Amplifiers or drivers can be used to achieve one or a combination of the following objectives:

• Provide gain to the input signal to increase the ADC resolution.
• Buffer or transform the impedance between the input source and the ADC.
• Convert a single-ended input signal to a differential output signal.

In doing so, the amplifier introduces noise into the ADC inputs thereby affecting its performance (SNR). In this article, I explain how to interpret the datasheet of an amplifier and that of an ADC and using some basic math, arrive at an estimated SNR when a particular amplifier-ADC combination is chosen.

The ADC chosen for this experiment is the AD9268-125 and the Variable Gain Amplifier (VGA) is the AD8352. Using the datasheet numbers for the Noise Spectral Density (NSD) of the amplifier (20nV/√Hz into a 150Ω load), I can prove that the performance of the system that uses the AD8352 to drive the AD9268 will be dominated by the amplifier noise. This means that using the AD8352 to drive the AD9268 will result in an ENOB of about 11.8bits.

This same technique can be used to estimate the performance of any amplifier – ADC combination thereby helping the customer make a more informed decision on the amplifier selection for a particular ADC.

The article can be accessed here:

Understanding How Amplifier Noise Contributes to Total Noise in ADC Signal Chains

Please feel free to post comments or feedback on this article or amplifiers and ADCs in general.

Cheers,

Umesh

ADI’s Blackfin processor based DRM radio was one of the first designs that met all Minimum Receiver Requirements (MRR) stipulated by the DRM standards. The success can be attributed to an excellent team where ADI managed and partnered with BBC in UK, Dolby (erstwhile Coding Technologies), Deutsch Welle and AFG Engineering in Germany.  The technology and reference design was then adopted by manufacturers to engineer and make products.  Now, a few other companies are in process of using this design for making digital radios in India as well. 

Read more about ADI’s solution: The article on The Successful Implementation of High-Performance Digital Radio. The article describes the details about the implementation and field trials.

Digital Radio Mondiale (DRM) is a non-proprietary digital radio developed for over-the-air transmission system developed for the broadcasting bands around 30 MHz.  It is targeted for world-wide and can be transmitted over long wave, medium wave, shortwave, and FM band I, II and III. With near-FM quality sound that offers a dramatic improvement over analog AM.  DRM also provides enhanced features like SlideShow, EPG, etc. DRM below 30MHz is called DRM30 and above is called DRM+. There are other three more very popular digital wireless radio systems recognized by the International Telecommunications Union: the two European systems DAB/DAB+ system and the Japanese ISDB-T and the U.S. HD-Radio (IBOC). 

1. http://www.analog.com/library/analogdialogue/archives/47-01/digital_radio.html
2. http://www.drm.org/

I wrote an article appearing in this month’s Analog Dialogue that shows how compensating an amplifier—such as the ADA4895-2, which is normally stable for a gain higher than +9— to operate with a gain as low as +2, provides higher slew rate and faster settling time than an equivalent internally compensated amplifier. Two methods were presented, one adds an RC circuit  from the inverting input to ground whereas the second adds a  resistor between the inverting and non-inverting inputs. Finally advantages and disadvantages of each circuit were highlighted.

The ADA4895-1/ADA4895-2, part of the ADA4896-2/ADA4897-1/ADA4897-2 family, are low-noise, high-speed, voltage-feedback amplifiers with rail-to-rail outputs. Stable with a minimum gain of 10, they feature 1.5-GHz gain-bandwidth product, 940-V/μs slew rate, 26-ns settling time to 0.1%, 2-nV/√ Hz 1/f noise at 10 Hz, 1-nV/√ Hz wide band noise, and −72-dBc spurious-free dynamic range at 2 MHz. Operating with a 3-V to 10-V supply, they draw a quiescent current of 3 mA per amplifier.

Read the full article titled Compensating Amplifiers that are Stable at Gain ≥ 10 for Lower Gain Operation.

I’m interested to hear your valuable feedback or any comments you may have on this article or surrounding this topic in general. You can leave your feedback in the comment section below.

Regards,

Charly

Q: How many digits should I use to represent measured or calculated data?

A: The number of significant digits should always make sense in view of the nature of the data and its intended use: neither too few to be useful nor too many—to avoid confusion and erroneous interpretations of the data’s accuracy.

Learn more about significant  digits in The Decline of Rounding, as published in the December 2012 issue of Analog Dialogue.

We welcome your feedback. Has this article helped you in your design? Would you like more information on this topic?

Best regards,

Scott

Increased need for smaller, cheaper and more readily available ECG equipment worldwide drives integration within this patient focused space. Silicon integration can easily capture obvious functional blocks condensing amplifiers, converters and switches with relative ease. Inclusion of appropriate digital post processing capabilities on chip delivers a solution centred  outcome targeted at enhancing overall offering, shortening end user design cycles, as well as increased value add. With the numerous challenges facing designers to satisfy functional, performance, program and regulatory demands, solutions designed with a emphasis on simplifying end system challenges provide a welcome head start.

Patient monitors, whether in or out of hospital will deliver on a particular feature-set suited to their end use application, such as channel count, types of measurement such as thoracic impedance measurement, pace maker detection, SpO2, or temperature to name a few. In addition to such features, systems get distinguished by performance requirements such as diagnostic or monitor requirements and form factor restrictions to ensure patient comfort all come into the mix.

When heart patients with implanted pacemakers undergo electrocardiogram (ECG) testing, a cardiologist must be able to detect the presence and effects of the pacemaker. The electrical signature of the pacing signal consists of small, narrow pulses. Buried in noise and larger cardiac signals, these artifacts can be difficult to detect.

With almost half a million pacemakers implanted worldwide each year, these ECG instruments must be capable of identifying and distinguishing a pacemaker signal or artifact from the ECG capture. Some equipment will have this implemented using a hardware detection circuit while others will use their own post processing in the digital domain.