Capacitor Layer Reduces Impedance in VCSEL Driving Circuit

The invention transitions from a planar chip-type capacitor to a three-dimensional capacitor layer formed within the substrate thickness direction. The capacitor layer extends through multiple layers including dielectric layers and electrode patterns arranged in stacked configurations, utilizing the vertical dimension to increase capacitance without increasing planar area, thereby reducing impedance while maintaining compact device size.

The capacitor layer is nested within the substrate structure, with capacitor electrodes integrated into the substrate's internal layers. The dielectric layers and electrode patterns are embedded within the substrate thickness, allowing the capacitor to be formed inside the substrate rather than as a separate surface-mounted component, achieving space-efficient integration that reduces impedance without increasing overall device volume.

The invention resolves the area-capacitance trade-off by moving from two-dimensional planar capacitor design to three-dimensional stacked capacitor layers. Multiple dielectric and electrode layers are arranged in the vertical direction, creating a capacitor with large effective area without increasing the substrate's planar footprint, thus reducing impedance while maintaining compact device area.

The capacitor layer employs composite structures combining multiple dielectric materials and conductive electrode patterns stacked together. This composite approach allows the capacitor to achieve high capacitance values through the cumulative effect of multiple thin layers, providing large capacitance in a vertically compact configuration that does not increase substrate area.