Integrated Magnetics Manufacture

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Integrated Magnetics Manufacture

• Two-fold strategy to extend the power levels and
  applications for which magnetic components can be
  manufactured in an integrated fashion
• a three-dimensional copper electroforming process
  offers larger-valued, higher-Q power inductors
  than are achievable with traditional thin-film
  processing
• multi-resonant L-C networks exhibit immitance
  peaks at predictable, harmonically related
  frequencies, and can replace inductors that are
  impractically large for on-die manufacture

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Tapped toroidal structures
Tapped toroidal inductors and transformers can be
fabricated in a two-layer copper electroplating
process, in which winding turns are plated into
or over epoxy molds. Uniformly spaced radial
electrodes, when tapped with capacitors, can
develop odd-harmonic impedance maxima at driving
terminals.
Capacitor taps
Wells (dark rectangles) act as molds to shape
subsequent layers of electroplated copper.
The lowest layer of 10?m copper (light regions)
connects turns of the magnetic structure, and
forms an electroplating seed layer
capacitors and the complete set of radial taps
omitted for clarity
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3D Fabrication Electroformation

• Off-plane builds approaching 1 mm guide flux
  along substrate for lower loss
• Higher DC currents than thin-film, planar
  counterparts
• Epoxy scaffolds with conformal seed layers
  provide off-plane connections in a single plating
  step

substrate
seed
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Impedance characteristics

• Tapped toroidal inductors approximate, apart from
  stage- to-stage coupling, a lumped
  transmission-line model
• Odd-harmonic impedance maxima can be aligned to
  switching harmonics automatically

Measured Impedance Magnitude Zin
harmonics
1st
3rd
5th
RL
Zin
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Applications of multi-resonant structures

• PWM converters operating near 50 duty ratio
• Voltage-fed push-pull converters with isolation
• RF-to-DC converters, or class-F RF power
  amplifiers

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