A Monolithic RF Lowpass Filter on Diamond via Additive Manufacturing

This paper demonstrates the design, fabrication, and RF testing of a monolithic lowpass filter (LPF) on single-crystalline diamond (SCD). This is the first time an RF filter has been fabricated on SCD. The LPF consists of grounded coplanar waveguide (GCPW) and microstrip (MS) transmission lines, via-less GCPW-to-MS transitions, and a bottom ground plane, all printed on a 5 mm x 5 mm x 0.15 mm SCD wafer with Aerosol Jet Printing technology using silver ink. The LPF is a stepped-impedance filter designed to have a cutoff frequency of 40 GHz and was measured from 10 MHz up to 67 GHz. Our results indicate that SCD is a good platform for the realization of high-frequency RF structures on a single substrate using additive manufacturing techniques.