A 3D miniaturization method for low impedance designs

Microstrip interconnects with a V conductor are designed, fabricated, and measured to provide a compact solution for designs requiring low characteristic impedance lines. S-parameter curves are shown up to 35 GHz for 0.5 cm long designs. The 308 μm deep V structure produces a 33.8 Ω line with strong standing waves and reflections under 5 dB. To further reduce the impedance, a partial shield is added that results in 6.7 times reduction of signal line width, near elimination of open end effect, and excellent correlation with a standard 15 Ω microstrip up to 25 GHz. A filter demonstration shows near ideal behavior in 3 dB response and low return loss when compared to a similar design.