Picor Active Filters Overcome Space
and EMI Challenges for Helicopter Displays
Designers are replacing bulky cathode-ray tube (CRT) helicopter displays with much thinner and space-efficient liquid crystal displays (LCDs). For new applications, some are specifying LCDs as small as 2.5 in across to make the most of the cockpit space. These changes make new demands on power and the need to manage EMI (electromagnetic interference).
In this context, designers of helicopter displays were faced with the dual challenge of squeezing as much functionality as possible into a small space as well as dealing with the electromagnetic interference (EMI) from systems that operate at increasing frequencies. The small space constraints made it difficult to use conventional passive shielding techniques, which are often bulky.
Picor active EMI filters, however, met the stringent requirements of, for one example, the US Department of Defense DO160 standard and provided higher attenuation than passive filters in a much smaller space. Picor’s QPO-1 active filters provide output ripple and noise attenuation of more than 30 dB from 1 kHz to 500 kHz and more than 20 dB in the 50 Hz to 500 Hz range. A single module replaces at least five bulky passive components and provides better results.
Able to support load currents up to 10 A, the tiny filter module can handle a wide voltage range from 3 V to 30 V DC. As well as providing better noise attenuation than a bulky network of external passive components, the QPO-1’s closed-loop architecture improves transient response – vital for modern embedded computers and displays – and ensures quiet point-of-load attenuation.