A Note From the Editor

Today I want to draw your attention to our StudentZone article “Making an Operational Amplifier from Previous Blocks.” For all of you that want to measure within an operation amplifier, I recommend the PCB below. Perhaps you remember our previous articles about input stages, differential pairs, current mirrors, current source, current sink, and zero gain amplifiers. Combining those individual functions and schematics together, you have the basic schematic of a bipolar op amp.

PCB

The PCB is the base to build a discrete build bipolar op amp. A PCB was generated with 11 transistors and some passive components. You can find the design files on our GitHub page. A nice detail is that the PCB comes with the 8-pin standard DIL/SOIC outline. This means you can replace an 8-pin DIL single op amp with this PCB in a real application. This would enable you to measure signals within the op amp. This is a charming solution not only for students and professors but also for any technical enthusiasts.

And now, back to the articles in this month’s issue of Analog Dialogue

Many data acquisition (DAQ) applications need to isolate the DAQ signal chain path for robustness, safety, high common-mode voltage reasons, or to eliminate ground loops that can introduce an error into a measurement. However, to achieve high AC performance, such as signal-to-noise Ratio (SNR), the system designer must consider the error introduced by jitter on the clock signal or convert-start signal that controls the sample-and-hold switch in the ADC. Jitter on the signal controlling the sample-and-hold switch becomes a more dominant error as the signal of interest and sample rates increase. So far LVDS is the preferred interface format for precision high speed ADCs because of the high data rate requirements. It also creates minimal disturbance on the DAQ power and ground planes. Authors John Neeko Garlitos and Lloben Paculanan will explain how to interpret the jitter specification on Analog Devices’ LVDS digital isolator products in the article, “The Easy Steps to Calculate Sampling Clock Jitter for Isolated, Precision High Speed DAQs.”

Different from conventional radio communications, frequency hopping (FH) transmits signals by rapidly changing carrier frequency. With an increase in hop rate and a larger set of frequency sub-bands, the advantages of FH have become more prominent. Michelle Tan provides an in-depth discussion of the concept of FH and the flexible PLL architecture of the ADRV9002 in the article, “The Next-Gen, Software-Defined Radio (SDR) Transceiver Delivers Big Advances in Frequency Hopping (FH).” The ADRV9002 is a new generation of software-defined radio for applications such as Link 16 and fast real-time carrier frequency loading in both single- and dual-channel operation modes. A combination of FH, multichip synchronization (MCS), and DPD makes the ADRV9002 a very attractive solution for achieving advanced requirements in today’s complex communication systems.

Simulation plays a key role in building any system. It allows designers to foresee problems and prevent time-consuming and costly revisions. In high speed digital interfaces, if not designed properly, a simple PCB trace could affect the quality of the signal. In signal integrity simulations, an IBIS (Input/Output Buffer Information Specification) model is used as a representation of the device’s digital interfaces. “IBIS Modeling—Part 2: Why and How to Create Your Own IBIS Model” provides an illustrated guide on how to use LTSpice to create your own IBIS Model. The guide covers premodeling procedures to IBIS model validation.

Many of today’s applications require smaller form factors while maintaining the same performance parameters. Developers are often faced with the question of how to realize this and frequently must make do with compromises. Several discrete components are usually used from the sensor to the analog-to-digital converter (ADC). Instrumentation amplifiers, ADC drivers, reference buffers, and filters are often used too.  The article, “A New, Better Way to Optimize the Signal Chain with Continuous-Time Sigma-Delta Converters,” shows how to optimize signal chain design, minimize form factor, and reduce BOM costs.

In a continuation of our latest transistor-focused activities, this month’s StudentZone, “ADALM2000 Activity: Making an Operational Amplifier from Previous Blocks,” will be of special interest. In this activity, we will be combining various basic schematics and building a discrete operational amplifier using a PCB and external components like capacitors, resistors, and transistors. The PCB uses the standard 8-pin DIP single op-amp footprint and can be inserted into a solderless breadboard.

And as we have for 55 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.