Steady progress is being made on the DC-DC converters for the future collider detector front end chips. Our group is focused on air core inductors with 48 Volt feed into the Detector and explore the use GaN FETS to increase the overall power delivery efficiency.

Efficient power delivery has been recognized for many years as a major issue for large, high energy physics experiments. DC to DC conversion provides a means to reduce the cable bulk and mass, and to reduce the power and heat removal requirements of experiments. A buck converter is a switching power supply that can transform DC power using only one inductor. The energy is pumped into the magnetic field at the higher voltage and withdrawn at the lower voltage. If the buck converter operates at high frequency, the required inductance can be small enough that an air core inductor can be used in high magnetic fields. Collaborative efforts over more than five years by groups in Germany, at CERN, and elsewhere in Europe have made progress, but have also demonstrated that the requirements of high efficiency, low noise generation, small size and a large voltage reduction ratio are difficult to satisfy simultaneously. DC-DC converters are widely used in industrial and consumer electronics. The semiconductor is producing a wide variety of ICs for this purpose, many of which appear suitable for physics applications. Practical tests using actual physics detector prototypes and buck converters using commercial ICs and flat spiral air core coils have shown that this approach can provide low noise power at the point of load, with a small footprint and low mass. Radiation testing has also shown that rad hard devices for LHC detectors are possible. More work is required to further understand the switching noise and produce a practical prototype of a 2 stage power system that will produce 1.2V output from 48V input that meets the requirements of high efficiency, small size, low mass and operation in high magnetic fields. Much more work is necessary to take DC-DC converters from test bench objects to more complete power delivery systems which can be incorporated into the detectors of future experiments

Contact : Tsutomu Mibe (4344)
KEKDTP seminar web page : http://rd.kek.jp/seminar_01.html