A 20-MHz 1.8-W DC–DC Converter With Parallel Microinductors and Improved Light-Load Efficiency

Design Procedure for Racetrack Microinductors on Silicon in Multi-MHz DC–DC Converters

“…The available footprint area, A, is also defined at this stage. In line with conventional inductor design, these parameters are used to calculate the minimum winding width, W w,min for a given temperature rise using (13). Maximum flux swing due to saturation, ΔB max , is given in terms of applied current levels as:…”

“…The highest temperature rise was observed closest to the wire bonds and it is likely that an implementation without these wire bonds would have a lower temperature rise than that shown in Figure 11. Application of (13) with an inductor RMS current of I rms = 0.55 A for this winding predicts a temperature rise of approximately 16 o C for natural convection providing a reasonable starting point for determining thermal limits. Forced convection has a temperature rise of approximately 10 o C demonstrating the strong dependence on environmental factors.…”

“…The temperature rise of microinductor L2 was monitored when implemented in the circuit specification outlined in section III.B using an Infrared thermometer under two conditions; natural convection and forced convection where a 1 W fan was positioned approximately 10 cm away from the circuit. The microinductor was packaged in a similar fashion to [13] on a DIL (Dual-In-Line) package with 25 µm diameter gold wire bonds. To ensure the reliability of the wire bonds the level of rms current applied was conservatively limited to 0.55 A.…”

“…One of the more developed approaches for PwrSoC is the racetrack design where an elongated spiral inductor allows for a straight cored section whose anisotropic properties can be enhanced. Racetrack microinductors have previously been demonstrated in 20 MHz DC-DC converters [12,13], and they have been designed for high frequency operation up to 100 MHz with inductance levels in the order of 100's nH [5].…”

On-chip high performance magnetics for point-of-load high-frequency DC-DC converters

“…Therefore, thin-film fabricated microinductors and microtransformers are ideal components to be used in high switching frequency applications. Both, microinductors and microtransformers are in many research works fabricated and tested at higher switching frequencies up to 50 MHz [1][2][3][4][5][6][7]. Based on these first results, the implementation of micro devices in power electronic applications is expected to be successful.…”