A Note From the Editor

Welcome to the October Issue of Analog Dialogue.

While I was reading one of this month’s articles about the integration of passive components such as resistors, capacitors, inductors, and diodes, I remembered when Analog Devices had hybrid ICs in the portfolio. Here’s an example:




I received two sample ICs during my onboarding training 30 years ago. Different ICs and external passive components made a complete data acquisition system. What is now integrated was made on individual passive components back then. I remember an anecdote about a transformer used in one of those parts. Analog Devices had longer delivery times for one of the hybrids containing a specific transformer, but only during September each year. No one knew why, and it took years to discover what was a very simple explanation. In those days, the transformers were twisted by hand. It was a difficult task and only very few employees were able to do it well. Every August, one of those skilled transformer-twisters went on vacation. This created a shortage of available transformers and a 4-week delay of the hybrid IC. Fortunately, those times are over. Coils are now implemented on the IC level, such as in the ADuMx digital isolator families.

Back to the present and the articles in this month’s Analog Dialogue.

As I mentioned, integrated passives are not new in our business. They are long established and well understood. When standalone discrete passives, or even integrated passive networks, are included as part of a chipset, routing parasitics, device compatibility, and board assembly considerations will still require careful design management. While integrated passives continue to have strong play in the industry, their most significant value begins to be realized only when they are included in system in package (SIP) type applications. Pat McGuinness and Mark Murphy discuss this in their article. Pat and Mark work with the Precision Converter Group in Limerick, Ireland, so you are getting insight directly from the IC designers.

Voltage controlled current sources (VCCSs) are widely used in many areas. The dc precision, ac performance, and drive capability of the VCCS are very important in these applications. The article from Nick Jang analyzes the enhanced Howland current source (EHCS) circuit’s limitation and improves it with composite amplifier topology to implement a ±500 mA current source with high precision and fast settling. Nick is a product applications engineer in the Linear and Precision Technology Group based in Beijing. He graduated from Xi'an Jiao Tong University with a master’s degree in electrical engineering.

Modern signal processing system design utilizing ADCs, PLLs, and RF transceivers demands lower power consumption and higher system performance. Selecting proper power supplies for those noise-sensitive devices is a common pain point for system designers. There is always trade-off between high efficiency and high performance. Traditionally, LDOs are often used to power those noise sensitive devices. Switching regulators are more efficient than LDOs, but they are too noisy to directly power ADCs or PLLs. One of the noise sources of switching regulators is the output ripple, which can appear as distinct tones or spurs in an ADC’s output spectrum. Rick Yang introduces you to an approach to implement a second-order LC filter in a switching regulator. Rick has spent the last 10 years in the power management group based in Shanghai, China working on various switching regulators and related system design. He graduated from Shanghai Jiao Tong University with a master’s degree in power electronics.

The majority of today’s available isolated gate drivers only accept a single supply on the output side. An increasing number of power devices need a negative gate drive voltage at the gate for better performance. This RAQ article details some elegant methods on how to operate a single supply gate driver in a bipolar method. Our author, Ryan Schnell, is an applications engineer at Analog Devices. His responsibilities include isolated gate drivers that use iCoupler® technology. He holds a B.S. and an M.S in electrical engineering, and a Ph.D. in power electronics from the University of Colorado.

In this month’s StudentZone, we take a look at low-pass and high-pass filters. We already discussed the main filter components—inductors and capacitors—in a previous StudentZone article. With this article we move forward with our ADALM series. Looking ahead, we will discuss different filters and related topics. Soon we will start addressing active components and semiconductor parts. I hope you’re still having fun with the ADALM1000.

And as we have for 51 years, we invite you to be part of the “dialogue” in Analog Dialogue. You can get in touch through our blog, Facebook page, or email. Let us know how we’re doing and what you’d like to see from us in the coming months.