Low-loss Glass Substrate Research Articles

Electrical Performance Analysis of High-Speed Interconnection and Power Delivery Network (PDN) in Low-Loss Glass Substrate-Based Interposers.

In this article, electrical performance analysis of high-speed interconnection and power delivery network (PDN) in low-loss glass substrate-based interposers is conducted considering signal integrity (SI) and power integrity (PI). The low-loss glass substrate is a superior alternative to silicon substrate in terms of high-speed signaling and fabrication yield. However, the low-loss of the substrate is vulnerable to power/ground noise in the PDN since the low-loss property of the substrate cannot suppress the noise naturally. In this article, an in-depth electrical performance analysis is conducted based on various measurements and simulations to fully benefit the advantages of the low-loss glass substrate. First, the fabrication process and test vehicles for the analysis are explained. Using the test vehicles, the electrical performance of the glass interposer's high-speed interconnection is compared with those of silicon and organic interposers. The insertion loss, eye-diagrams, and signal bandwidths of three interposer channels are compared and analyzed based on electromagnetic (EM) and circuit simulations. Also, the electrical performance of the through glass via (TGV) channel is measured and compared with through silicon via (TSV) channel. The high-speed interconnection of the glass interposer showed better performance for most of the parameters which is more suitable for maintaining the SI. Even though the low-loss of the glass substrate ensured the SI, power/ground noise issues in the PDN must be analyzed and solved. In this article, various cases inducing the power/ground noise in the PDN are considered, simulated, and measured. To solve the issues, ground TGV design and electromagnetic bandgap (EBG) design are proposed for an efficient broadband suppression of the noise generated in the glass interposer PDN.

Broadband and wide angle microwave absorption with optically transparent metamaterial

Abstract An optically transparent metamaterial for microwave absorber with wide operation angle, polarization insensitivity, broadband and high absorptivity was demonstrated. The metamaterial is composed of planar indium tin oxide (ITO) structures and low-loss glass substrates. By tailoring the reflection response of ITO patterns and the position of arrayed ITO resonators between quartz glass dielectric substrates, more than 90% absorption in the frequency ranges of 8–20 GHz and within a wide angular range from 0° to 60° is achieved. Meanwhile, by employing transparent substrates, including soda-lime glass and quartz glass, good optical transmittance (80%) is obtained. The dielectric loss of quartz glass is lower than other dielectric substrates, which implies that the high absorptivity was achieved mainly due to the contribution of planar ITO metamaterial structure. The reflectivity of proposed MMAs is simulated and measured experimentally. Both of which demonstrate excellent absorption performance of the metamaterial. The optically transparent broadband metamaterials absorber with high absorptivity and polarization insensitivity opens a horizon of potential applications in many fields.

Non‐linear characteristics of an optically reconfigurable microwave switch

A novel, high-power optically controlled microwave switch is presented. The switch uses integrated illumination of a silicon superstate through a low-loss glass substrate which reduces losses related to the plasma conductivity tail in the silicon. Numerical electromagnetic modelling is used to design the switch and good agreement between measured and simulated results has been achieved. The switch is then characterised using a two-tone non-linearity test at 2 GHz and a third-order intercept point of +72 dBm is obtained with 10 W per tone.

Improved RF Devices for Future Adaptive Wireless Systems Using Two-Sided Contacting and AlN Cooling

This paper reviews special RF/microwave silicon device implementations in a process that allows two-sided contacting of the devices: the back-wafer contacted silicon-on-glass (SOG) substrate-transfer technology (STT) developed at DIMES. In this technology, metal transmission lines can be placed on the low-loss glass substrate, while the resistive/capacitive parasitics of the silicon devices can be minimized by a direct two-sided contacting. Focus is placed here on the improved device performance that can be achieved. In particular, high-quality SOG varactors have been developed and an overview is given of a number of innovative highly-linear circuit configurations that have successfully made use of the special device properties. A high flexibility in device design is achieved by two-sided contacting because it eliminates the need for buried layers. This aspect has enabled the implementation of varactors with special Ndx -2 doping profiles and a straightforward integration of complementary bipolar devices. For the latter, the integration of AlN heatspreaders has been essential for achieving effective circuit cooling. Moreover, the use of Schottky collector contacts is highlighted also with respect to the potential benefits for the speed of SiGe heterojunction bipolar transistors (HBTs).