The sharing of ideas and techniques between RF and power isn't new, having existed for almost as long as electrical engineering. A vacuum tube diode detector with its resistor-capacitor filter for AM broadcast reception, for example, had plenty of similarities to a linear dc power supply with an inductor-capacitor filter. Similarly, today's RF switch-mode amplifier might be considered the younger cousin of the switch-mode power supply.

What's different now is that the RF-and-power relationship takes on greater significance in the dc power arena as the world moves from the analog domain to the digital.

In the RF world, spread-spectrum systems are used to achieve secure voice or data communications. But their use in dc power has only become familiar to PC OEMs within the past decade. That seems sure to change.

The latest SS applications reduce electromagnetic interference (EMI) in equipment-dense systems. The idea is to apply the modulating signal provided by, say, a pseudo random number generator to the system oscillator. That technique spreads the oscillator's energy over a band of about 20 percent to each side of its fundamental frequency. As a result, the energy in each harmonic is greatly minimized, often eliminating the need to filter out system harmonics later on. Attacking potential EMI at the source, when possible, simplifies the challenge and cuts down on costs.

A new dc/dc regulator IC from Linear Technology Corp. is said to be the first of its kind to use spread spectrum. The company's LTC3251 is a step-down inductorless converter operating at 1 MHz that delivers up to 500 milliamps. It has an ultraclean output, the company says, for wireless applications.

The SS technique is one the company plans to apply as much as possible to future products. I have a feeling this RF technique won't be the only one to come down the pike near-term to handle more critical commercial, industrial and medical applications in power. With power being as important as ever, new techniques won't necessarily be confined to the RF domain. And that's not just noise talking.