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Open AccessArticle

Surface-Mount Zero-Ohm Jumper Resistor Characterization in High-Speed Controlled Impedance Transmission Lines

by Aleksandr Vasjanov and Vaidotas Barzdenas

Sensors 2023, 23(9), 4472; https://doi.org/10.3390/s23094472 - 4 May 2023

Cited by 1 | Viewed by 6057

Zero-ohm resistors, also known as jumpers, are commonly used in early radio frequency (RF) prototypes as they can help engineers identify the most optimal engineering solution for their system or create application-specific hardware configurations in products. One of the key considerations when using zero-ohm jumpers in RF circuits is the potential for signal loss and interference. Every circuit connection creates a small amount of resistance and impedance, eventually adding up over long distances or in complex circuits. This paper proposes a quantitative characterization summary of standard 0201-, 0402-, 0603-, and 0805-size surface-mount package jumpers, as well as lead-free and lead solder wires, in high-frequency applications by means of time domain reflectometry (TDR) and S-parameter measurements. The typical offset from the target 50 Ω impedance was measured to be around 3 Ω, or 5.8% relative to the measured reference value. According to S-parameter measurement results, no visible impact on attenuation was spotted up to 5 GHz compared to the reference S₂₁ curve. Full article

(This article belongs to the Special Issue MIMO Technologies in Sensors and Wireless Communication Applications)

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27 pages, 17589 KB

Open AccessArticle

A Study on Over-Molded Copper-Based Flexible Electronic Circuits

by Mona Bakr, Martin Hubmann, Frederick Bossuyt and Jan Vanfleteren

Micromachines 2022, 13(10), 1751; https://doi.org/10.3390/mi13101751 - 16 Oct 2022

Cited by 5 | Viewed by 3562

Abstract

Over-molding has been proposed in recent years as an integrated functional flexible circuit board in a plastic part. This method uses the conventional process for film insert technology. Over-molding has attracted significant attention across many industries due to its potential to deliver different electrical functions in a variety of different part geometries, especially in automotive interiors and home appliances. While it has great application potential, manufacturing challenges continue throughout foil fabrication and injection molding. This raises challenges for designers and researchers responsible for maintaining the reliability of such electronic flexible circuits. Therefore, the purpose of this research paper is to improve some of the over-molding process parameters. On 0805 and 1206 over-molded zero-ohm resistors, electrical, mechanical, and failure characterization was performed. Those components were mounted in parallel, perpendicular, and 45° angled arrangements on two different polymer substrates, polyimide (PI) and polyethylene terephthalate (PET) using lead-free solder, low-melt solder, and conductive adhesive paste. Moreover, as an over-molding material, polycarbonate (PC) with medium viscosity was used. The effect of using different mold shapes (corner mold, 2 mm flat mold, and 3 mm flat mold) and injection molding process parameters (injection speeds and melt temperature) was studied. Full article

(This article belongs to the Special Issue Flexible and Wearable Sensors)

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15 pages, 4813 KB

Open AccessArticle

Analysis and Design of a Microphone Preamplifier for Mobile Applications

by Saemin Im and Sang-Gyu Park

Electronics 2021, 10(14), 1624; https://doi.org/10.3390/electronics10141624 - 7 Jul 2021

Cited by 2 | Viewed by 5727

Abstract

A design of an on-chip ac-coupling preamplifier for mobile applications is presented. A microphone preamplifier should have a large input impedance to mitigate the effective-gain reduction caused by the microphone’s non-zero output impedance. From a review of previously reported microphone preamplifier structures in terms of input impedance, feasibility of on-chip ac-coupling, and noise performance, we chose an inverting amplifier structure with capacitive feedback. In addition, to provide dc bias path, we used off-state MOSFET switches as pseudo-resistors of very large resistance in the giga-ohm range. The large resistance enables on-chip ac-coupling with sufficient noise performance. A fast start-up is achieved by turning-on the switch for a short period during the preamplifier start-up. The gain of the preamplifier can be programmed from 0 dB to 21 dB with 3 dB steps. A 2-stage pseudo-class-AB amplifier was adopted to reduce power consumption. The proposed preamplifier was implemented using a 28 nm CMOS process and achieves 107 dB dynamic range in a 20 kHz bandwidth under 0 dB gain setting and balanced differential input signal. The preamplifier dissipates a power of 270 μW with a 1.8 V supply. Full article

(This article belongs to the Section Circuit and Signal Processing)

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19 pages, 8948 KB

Open AccessFeature PaperArticle

Forward Converter Current Fed Equalizer for Lithium Based Batteries in Ultralight Electrical Vehicles

by Ali Farzan Moghaddam and Alex Van den Bossche

Electronics 2019, 8(4), 408; https://doi.org/10.3390/electronics8040408 - 8 Apr 2019

Cited by 20 | Viewed by 5008

Abstract

In this paper, the concept of a forward balancing technique fed by a buck converter for lithium-based batteries in Electrical Vehicle (EV) applications is investigated. The proposed active topology equalizes eight cells in a series in a battery pack, by using a forward converter for each battery pack and the whole battery packs, using a buck converter. The battery bank consists of four battery packs, which are in series. Therefore, the proposed system will equalize 32 cells in series. In this paper, the proposed circuit employs a single transistor used in a Zero Voltage Switch (ZVS) for the forward converter. In practice, this means a capacitor in parallel with the switch at the same time a demagnetizing of the transformer is obtained. The circuit realizes a low Electromagnetic Interference (EMI) and reduces ringing. To overcome the problem of many pins on a coil former, the transformer secondary windings are made by using hairpin winding, on a ring core. It permits, e.g., having eight secondaries and uniform output voltages. Each secondary winding is made by two hairpin turns using two zero-Ohm resistors in series. The proposed topology has less components and circuitry, and it can equalize multiple battery packs by using a single buck converter and several forward converters for each battery pack. Experimental and simulation results are performed to verify the viability of the proposed topology. Full article

(This article belongs to the Section Electrical and Autonomous Vehicles)

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