Optimizing your system through careful resistor choices

7/22/2010 11:47 AM EDT

The need to reduce the size and number of passive components on a pc board is as real as it was 50 years ago, and for the same reasons: to save on cost and space. As real and vital as this need remains, so too does the balancing act that must be performed to get there in terms of performance, particularly, as in the case of resistors, with regard to precision, thermal stability, noise and ESD protection.

While advanced materials and approaches such as polymer thick film and the integration of passives within the layers of a board may be gaining traction, the core resistor technologies – wirewound, thick film, thin film and foil – too are advancing, though each have their sweetspot in any system design. Power wirewounds are still preferred for the output of a high-power amplifier, while it still may be best to opt for a precision wirewound or a thin-film chip resistor for a low-noise input circuit.

To see how far these devices have come in terms of performance for their respective application, I've put together a few really interesting features from Vishay, and present them here in a one-two combo package that starts out with a comparative overview of each resistor technology and its relative performance characteristics. It looks at its underlying material, manufacturing process and how that process affects performance. It compares them on all critical performance criteria and concludes with a checklist of what you as a designer must keep in mind when deciding just how much performance is adequate to optimize your system.

As the author points out, while it may be tempting to throw a bit of back-end processing in to smooth out any passive-component fallibilities, that may cost you in the long run.

In the second punch, we zoom in on thin-film resistors and how they can accommodate the demand for reduced size, higher precision and increased electrical stability through the integration of multiple resistors on a single ceramic substrate.

We hope you enjoy these two features on what is a critical yet often underestimated technology in terms of how it can affect your design. In particular I'd like to thank the authors, Yuval Hernik and Dr. Carsten Bronskowski, respectively, on an excellent job bringing these issues to the fore in such a helpful and useful fashion. Nice job fellas!