Analysis of a Microstrip Wide Band Antenna by Solving Volume-Surface Integral Equations

In this paper, a method based on hybrid Volume-Surface Integral Equation (VSIE) formulation in combination with Green's Function is presented to analyze a wide band planar microstrip antenna. Hybrid volume-surface Mixed Potential Integral Equation (MPIE) is used to analyze the structure. This hybrid integral equation is solved with the aid of spatial-domain Method of Moments (MoM) in order to compute surface current in metal faces and volume charge densities in dielectric substrate. The antenna is fed via a coaxial probe which is modeled in the developed code. Accuracy of the presented method is validated by comparing the results obtained from the proposed method with those of CAD simulations and measurements results

Transient Response of ESD Protection Devices for a High-Speed I/O Interface

System-efficient electrostatic discharge (ESD) design (SEED) models of a diode and transient voltage suppressor (TVS) were developed to study their transient response in a high-speed input/output interface. Previously reported SEED models were improved to strengthen their convergence stability and facilitate accurate predictions over a wide range of conditions. These improvements were required to accurately capture the race conditions between the TVS and on-chip diode, where the diode\u27s turn on may prevent turn on of the TVS. Simulations and measurements were performed to demonstrate the impact of the ESD pulse\u27s rise time on race conditions. During a race, results showed the worst-case quasi-static diode current could be twice as high for long rise-time pulses than for short rise-times where the TVS does not turn on, and on-chip diode current may be larger at low test voltages than at high test voltages where the TVS does turn on. Adding a small passive impedance between the external TVS and the on-chip diode helps the TVS turn on and reduce the current through the on-chip diode by more than 50%. Similarly, lengthening the trace between the TVS and diode could reduce on-chip diode current by up to a factor of two

Race Conditions among Protection Devices for a High Speed I/O Interface

The ESD coupling path and on-board impedances strongly affect the ESD rise time seen on a PCB trace. Possible race conditions between external and on-die ESD protection were studied using measurement-based models of the transient response and on-board passives. Results show the interplay of rise time and protection turn-on can prevent the external TVS from responding in time

System-Level EMI of an Artificial Router System with Multiple Radiators: Prediction and Validation

In a multimodule system, an increase in the number of radiating optical modules will increase the electromagnetic emissions. This article investigates the scaled tendency of the emissions in a router system loaded with hundreds of optical modules. An artificial router mimicking the real system was built to investigate this tendency. A patch antenna array mimics the radiation of the optical modules. It can be excited in in-phase and random-phase configurations. The measurement data verifies the theoretical analysis and the prediction from a statistical method without performing hundreds of different experiments on a real router. Assuming that all radiators are radiating at the same frequency and have similar radiation pattern with random phases, the average of the maximal directivity of the system will saturate if the number of radiators (N) is larger than 14. Furthermore, the average of the maximal electric field radiated will increase following a 10 log10 N (dB) tendency