Suppression Of Noise Coupling Research Articles

2.4\xa0GHz wake-up receiver with suppressed substrate noise coupling

The switching noise generated in digital circuits propagates through conductive silicon substrate to analog circuits in a mixed-signal CMOS LSI. Substrate noise coupling may degrade the performance of the analog circuits, and may result in a fault operation of the mixed-signal LSI in the worst-case. In this paper, the substrate noise coupling between the clock recovery circuit and the input port of the envelop detector in a low-power wake-up receiver (WuRx) was investigated experimentally. The propagation path of the substrate noise coupling was clarified by comparing the experimental results with the circuit simulations on the basis of an equivalent circuit model. The design of the WuRx was modified on the basis of the findings to suppress the substrate noise coupling. The fabricated WuRx successfully operated a 100-kbps PWM signal with a carrier frequency of 2.4 GHz, and the effectiveness of the noise coupling suppression recipe was confirmed.

Reduction of Electromagnetic Noise Coupling to Antennas in Metal-Framed Smartphones Using Ferrite Sheets and Multi-Via EBG Structures

Recent smartphones increasingly employ a metal frame for a sophisticated design. However, the metal frame becomes a good coupling path for electromagnetic (EM) noise within smartphones and increases noise coupling to radio-frequency antennas located at the top and bottom sides of the smartphones. This paper proposes two novel metal frame structures with ferrite absorbing sheets or electromagnetic band gap patterns to reduce the coupling of EM noise to the antenna. Using a fabricated test board, the effects of the proposed metal frames on noise coupling suppression are experimentally validated.

An Electrostatic Discharge Protection Circuit Technique for the Mitigation of Single-Event Transients in SiGe BiCMOS Technology

The impact of electrostatic discharge (ESD) protection circuits on the single-event transients (SETs) of RF building blocks in a 130-nm SiGe BiCMOS (8HP) platform is investigated. For proof-of-concept that SET mitigation can be accomplished through the use of an ESD protection circuit, a single-pole single-throw (SPST) switch was implemented using triple-well nFETs. For substrate noise coupling suppression, a P+, P− substrate (Psub) and N-well guard ring structures were applied. According to two-photon absorption laser experiment results, the SPST switch with ESD protection exhibits the smallest transient peaks at the RF input/output and $\text{V}_{\mathrm {\mathbf {DD}}}$ ESD terminals. Based on these results, an SET mitigation strategy is proposed while maintaining the optimal circuit performance.

A Novel Shielding Effectiveness Matrix of Small Shield Cans Based on Equivalent Dipole Moments for Radio-Frequency Interference Analysis

A definition of a shielding effectiveness (SE) matrix for small shield cans used to suppress intra-system noise coupling in mobile devices is proposed. Assuming shield cans enclosing a noise source can be modeled as equivalent dipole moments along with integrated circuits (ICs), a new SE matrix for radio-frequency interference analysis is defined as a ratio of equivalent dipole moments with and without a shield can. The equivalent dipole moments are experimentally extracted using a GTEM cell and two types of probes (monopole and loop), which mimic well the radiations of ICs. Furthermore, the estimation of suppression of noise coupling to an antenna using the proposed SE matrix is successfully validated through numerical simulations.

A working single-level trap model and a resistivity scaling law for the proton-induced high-resistivity silicon

A particle-enhanced isolation technology had previously been proposed to direct energetic proton flux on VLSI-processed mixed-mode IC wafers before packaging for the prevention of undesirable substrate coupling [C.P. Liao, D. Tang, H.C. Lu, Creation of local semi-insulating regions on semiconductor substrates, US Patent 6,046,109, April 4, 2000]. Results of an improvement of 25–30 dB in noise coupling suppression and a great enhancement of two to three folds on Q values of on-chip inductors had also been reported [C.P. Liao, M.N. Liu, K.C. Juang, Cross-talk suppression in mixed-mode IC's by the π technology and the future with a SOC integration platform: particle-beam stand (PBS), IEEE Trans. Electron Dev. 50 (3) (2003) 764 (special issue on RF and SOC); C.P. Liao, T.H. Huang, C.Y. Lee, D. Tang, S.M. Lan, T.N. Yang, L.F. Lin, Method of creating local semi-insulating regions on silicon wafers for device isolation and realization of high Q inductors, IEEE Electron Dev. Lett. 19 (12) (1998) 461–462; C.P. Liao, C.W. Liu, Y.M. Hsu, Observation of explosive spectral behaviors in proton-enhanced high- Q inductors and their explanations, IEEE Trans. Electron. Dev. 50 (3) (2003) 758 (special issue on RF and SOC)]. Today, continued improvement of this technology has led to a new VLSI back-end facility: the particle-beam stand (PBS), which may ultimately become the general SOC (system-on-a-chip) integration platform. However, so far the mechanism and TCAD model behind such an approach have yet to be quantitatively determined. In this work, the establishment of an effective, self-consistent, 1-level trap model is attempted through fitting the existing single-trap-level theory [J.L. Moll, Physics of Semiconductors, McGraw-Hill, New York, 1964 (Chapter 6)] with experimentally obtained parameters and the assistance from numerical simulations of the SRIM (The Stopping and Range of Ions in Matter) code [SRIM—The Stopping and Range of Ions in Matter, a computer code constantly updated by J.F. Ziegler, J.P. Biersack. Available from: 〈 http://www.srim.org/〉. A full description of the calculation is found in The Stopping and Range of Ions in Solids, by J.F. Ziegler, J.P. Biersack, U. Littmark, Pergamon Press, New York, 2003] (a charged-particle stopping-power calculation program). It is revealed that, more than merely simple traps of charge carriers, those proton-created defects are also intrinsically charged (carrying +e or −e) and thus all are participating in the Rutherford-like scattering of the remaining free charge carriers escaping the defect trapping. The found effective single trap levels ( E T) are about +0.24 eV in n-Si and −0.34 eV in p-Si, measuring from the middle of the energy bandgap. Finally, a scaling law for such proton-rendered resistivity enhancement is given.

Substrate coupling in a high-gain 30-Gb/s SiGe amplifier-modeling, suppression, and measurement

For demonstrating substrate coupling in high-gain broadband amplifiers, a limiting differential transimpedance amplifier has been developed and fabricated in a SiGe bipolar technology. It operates up to 30 Gb/s and stands out for a maximum (nonlinear) transimpedance in the limiting mode of 25 k/spl Omega/, resulting in a gain /spl times/ speed product as high as 750 k/spl Omega//spl middot/Gb/s. This record value could be achieved by applying several techniques for suppression of noise coupling simultaneously. The effectiveness of each technique was verified experimentally by measuring the output eye diagrams of different mounted amplifier versions. The high accuracy potential of the substrate modeling tools applied for optimizing the amplifier design has been demonstrated separately by measurements on special (mounted) test structures up to 40 GHz. These investigations also showed the strong degradation of shielding measures by bond inductances with increasing frequency.