A G-Band Glass Interposer Technology for the Integration of an Amplified Noise Source Based on SiGe BiCMOS 55-nm Technology

This paper introduces a substrate technology that integrates an amplified noise source (NS) based on SiGe BiCMOS B55 nm technology onto a glass interposer to reduce dielectric and transition losses. Previous work has focused on the development and characterization of the NS in two distinct configurations. In a first flavor, on-wafer noise measurements yielded to an extracted excess noise ratio (ENRav) level of 37 dB in the 140–170 GHz. In an alternative approach, the NS was packaged in a split-block with a WR5.1 flange termination for connection to commercial passive probes, achieving an ENRav level of up to 25 dB in G-band (140–220 GHz) corresponding to a 12 dB ENR reduction when compared to the on-wafer measurements. To reduce dielectric losses due to the substrate, this paper proposes a third integration route based on an ultra-thin glass interposer, AF32 from Schott. This solution implements femtosecond laser micro-machining to structure the interconnects, enabling the integration of the NS chip on the same substrate used to manufacture the coplanar probing tips, with the advantage of simplifying the signal propagation path. This work has achieved a tunable ENRav level of up to 29 dB in the 140–170 GHz range, with constant output impedance matching better than -12 dB across the entire frequency band.