Machine Learning Based PCB/Package Stack-up Optimization For Signal Integrity

PCB/package stack-up design optimization is time-consuming and requiring a great deal of experience. Although some iterative optimization algorithms are applied to implement automatic stack-up design, evaluating the results of each iteration is still time-intensive. This paper proposes a combined Bayesian optimization-artificial neural network (BO-ANN) algorithm, utilizing a trained ANN-based surrogate model to replace a 2D cross-section analysis tool for fast PCB/package stack-up design optimization. With the acceleration of ANN, the proposed BO-ANN algorithm can finish 100 iterations in 40 seconds while achieving the target characteristic impedance. To better generalize the BO-ANN algorithm, a strategy of effective dielectric calculation is applied to multiple-dielectric stack-up optimization. the BO-ANN algorithm will be able to output optimized stack-up designs with dielectric layers chosen from the pre-defined library and the obtained designs are verified by 2D solver

Experimental Characterization of Millimeter-Wave Substrate-Integrated Waveguide Interconnect with Slot Transition in Flexible Printed Circuit Boards

For high-speed communication services such as 5G technology, the use of millimeter-wave (mmWave) components substantially increases in mobile applications. The interconnect based on a substrate-integrated waveguide (SIW) is an efficient solution for connecting these devices. However, the SIW characteristics in the mmWave frequency range are not sufficiently presented from the practical viewpoint. In this paper, the experimental characterization of mmWave SIWs in flexible printed circuit boards (FPCBs) and their simulation results are presented. A practical method using balanced/single slot transition is proposed for microstrip-to-SIW transition. Using a full-wave simulation and genetic algorithm, the proposed slot technique is optimized. It is experimentally demonstrated that the cutoff frequency affects the operating band of the SIW differently. The per-unit-length losses of the full-mode and half-mode SIWs are obtained as 0.0375 dB/mm and 0.0609 dB/mm, respectively. Using the measurements, the SIW type effect on the transmission loss is quantitatively analyzed, and the loss is increased up to 62.4% at 39 GHz

A Proposed On-Die Oscilloscope for Monitoring of Power Noise Waveform Inside IC Due to Transient Stress Events

An on-die oscilloscope circuit is proposed to monitor the power noise waveforms inside IC due to the transient stress events for a more complete analysis of the effects of the transient stress events on the electronic systems. When the transient stress event occurs, the induced noise voltage waveform in the power supply is sampled and converted to digital data in real time. A trigger signal created by the event detector circuit is used to hold the digital data. The stored digital data inside the on-die oscilloscope are reconstructed back to the analog noise waveform based on the sampling process. The operation of each circuit block in the on-die oscilloscope is analyzed and validated by simulation and measurement results. The approximate bandwidth of the proposed on-die oscilloscope is extracted from simulation results. The power noise waveforms due to the transmission line pulse events and electrostatic discharge events are measured with an external oscilloscope instrument using cables and directly sampled and reconstructed by the on-die oscilloscope, and these measured and reconstructed analog noise waveforms are compared with each other

Electromagnetic Interference Shielding Effects in Wireless Power Transfer using Magnetic Resonance Coupling for Board-To-Board Level Interconnection

In this paper, we present the analysis of electromagnetic interference (EMI) shielding effects of wireless power transfer (WPT) using magnetic resonance coupling for board-to-board level interconnection. Board-to-board WPT consists of source coil, receiver coil, and load which are manufactured on printed circuit board (PCB). The coil is expressed as a simple equivalent circuit model, of which the components are calculated using the physical dimensions of the coil. It is verified that the results of model estimation in both frequency-and time-domain show a good correlation with simulated and measured results under 1GHz. Voltage transfer ratio (VTR) of board-to-board WPT was achieved to be 0.49. In addition, EMI shielding effects in WPT with materials such as ferrite and metal film is analyzed using verified model. The shielding effects of each film in WPT are compared by observing their magnetic field distribution

Electromagnetic Interference on Analog-To-Digital Converters from High-Power Wireless Power Transfer System for Automotive Charger

Wireless power transfer (WPT) technologies have been actively studied for electric vehicle (EV) battery charging applications. Electromagnetic radiated emissions from high-power WPT system are substantial, and its effects on an analog circuits cannot be ignored. In this paper, we investigated the electromagnetic interference (EMI) on analog-to-digital converters (ADCs) from high-power WPT system for the automotive charger. A 3-kW-class high-power WPT system for compact EV operating at 20 kHz was designed and validated via simulation results. An ADC chip was designed to analyze the effects of EMI from high power WPT system. Based on simulation results, we verified that the performance degradation of the ADC connected through a cable due to the coupled noise from high power WPT system

MoM Based Current Reconstruction using Near-Field Scanning

Multiple digital ICs sharing ground plane have potential problems of ground noise interference to each other. Current distribution on the ground plane can introduce intra-system EMC issues, which can possibly result in receiver desensitization issue in wireless devices. In this paper, a method of moment (MoM) based current reconstruction method is proposed to estimate the current on the ground plane. This method requires phased resolved near field data for accurate current reconstruction. The proposed method is validated by a numerical example. The current reconstructed from the proposed method is compared with the current from the simulation tool. The difference is within 3.5 dB which is acceptable for most engineering practice

MoM-Based Ground Current Reconstruction in RFI Application

A method of moment (MoM)-based current reconstruction method is proposed to estimate the surface current density on the ground plane. Current continuity property is automatically enforced with Rao-Wilton-Glisson basis function. Both the least square method and the optimization method are utilized to solve the inverse problem and obtain the ground current. The proposed optimization method is successfully validated with numeric simulations and also a real-world measurement example. The reconstructed current distribution on the ground plane is further used in a typical radio frequency interference (RFI) example to perform RFI estimation and provide guidelines for RFI design. The proposed MoM-based ground current reconstruction method can be valuable to estimate and debug RFI issues in early design stage

Novel Highly Flexible PCB Design Based on a Via-Less Meander Ground Structure to Transmit mm-Wave RF Signals in 5G Foldable Mobile Products

Recently, new form factors, such as foldable, have increased demand for mobile products.Moreover, mobile phones should support the RF signal frequency up to the mm-wave frequencydue to the expansion of 5G mobile products. Therefore, 5G foldable products require componentsthat facilitate both mm-wave RF transmission and ultra-high flexibility for interconnecting throughthe hinge structure of foldable products. To improve flexibility, a flexible PCB must be thin with noground vias in its bending section; in contrast, the low-loss flexible PCB for mm-wave transmissionmust be thick and have many ground vias, so there is a trade-off relationship between flexibilityand RF characteristics. This paper proposes a new flexible PCB structure that does not experienceproblems regarding signal transmission to the mm-wave band, even when folded 200,000 times.To overcome the physical limits of the trade-off relationship, an interlayer air-gap was formed; astructure with a via-less and meander ground shape is proposed. The simulated loss of the proposedstructure was 0.0254 dB/mm @ 10 GHz, and the isolation between signals ranged from 21.98 dBto 10 GHz. The simulated results of insertion loss and isolation were experimentally verified. Theproposed structure is currently being applied to the RF flexible PCB that interconnects through thehinge of a foldable phone, and is currently being mass-produced

Analysis of Wireless Power Transfer system design on active silicon interposer for low voltage applications in 3D-IC

In this study, a Wireless Power Transfer (WPT) system design on active silicon (Si) interposer for low voltage applications in 3D-IC is proposed. The proposed WPT system includes magnetically coupled coils, a full-bridge rectifier, and a voltage regulator. In order to validate the proposed system, we first design all of the system components. First, we design a three dimensional helix-type transmitter (Tx) coil with the size of 1.6 mm by 1.6 mm on PCB, and a spiral-type receiver (Rx) coil using 3 μm top metal CMOS process with the size of 1.5 mm by 1.5 mm on Si-interposer. Second, a CMOS full-bridge rectifier is designed on the active Si-interposer to convert the AC voltage received from the Tx coil to DC voltage, which will then be fed to the input of the voltage regulator. Third, we design a voltage regulator to deliver 1.5 V DC voltage supply to multiple low voltage devices in 3D-IC. Power transfer efficiency of the coil system, full-bridge rectifier including a filtering capacitor, and voltage regulator is calculated to be 55 %, 69.5 %, and 71 %, respectively from circuit simulations. The simulated whole system efficiency is found to be 27 %