- Substrate coupling
integrated circuit, a signal can couple from one node to another via the substrate. This phenomenon is referred to as substrate coupling or substrate noise coupling.
The push for reduced cost, more compact circuit boards, and added customer features has providedincentives for the inclusion of analog functions on primarily digital MOS
integrated circuits (ICs) forming
mixed-signal ICs. In these systems, the speed of digital circuits is constantly increasing, chips arebecoming more densely packed, interconnect layers are added, and analog resolution is increased. In addition, recent increase in wireless applications and its growing market are introducing a new set of aggressive design goals for realizing mixed-signal systems. Here, the designer integrates
radio frequency(RF) analog and base band digital circuitry on a single chip. The goal is to make single-chip radio frequencyintegrated circuits (RFICs) on silicon, where all the blocks are fabricated on the same chip. One of the advantages of this integration is low power dissipation for portability due to a reduction in the number of package pins and associated bond wire capacitance. Another reason that an integrated solution offers lower power consumption is that routing high-frequency signals off-chip often requires a 50Ω impedance match, which can result in higher power dissipation. Other advantages include improved high-frequency performance due to reduced package interconnect parasitics, higher system reliability, smaller package count, smaller package interconnect parasitics, and higher integration of RF components with VLSI-compatible digital circuits. In fact, the single-chip transceiver is now a reality.
The design of such systems, however, is a complicated task. There are two main challenges in realizingmixed-signal ICs. The first challenging task, specific to RFICs, is to fabricate good on-chip passive elementssuch as high-Q
inductors. The second challenging task, applicable to any mixed-signal IC and the subjectof this chapter, is to minimize noise coupling between various parts of the system to avoid any malfunctioningof the system. In other words, for successful system-on-chip integration of mixed-signal systems, thenoise coupling caused by nonideal isolation must be minimized so that sensitive analog circuits and noisy digital circuits can effectively coexist, and the system operates correctly. To elaborate, note that in mixed-signalcircuits, both sensitive analog circuits and high-swing high-frequency noise injector digital circuits may bepresent on the same chip, leading to undesired signal coupling between these two types of circuit via the conductive substrate. The reduced distance between these circuits, which is the result of constant technology scaling (see Moore's lawand the International Technology Roadmap for Semiconductors),exacerbates the coupling. The problem is severe, since signals of different nature and strength interfere,thus affecting the overall performance, which demands higher clock rates and greater analogprecisions.
The primary mixed-signal noise coupling problem comes from fast-changing digital signals coupling to sensitive analog nodes. Another significant cause of undesired signalcoupling is the
Crosstalk (electronics)between analog nodes themselves owing to high-frequency/high-power analogsignals. One of the media through which mixed-signal noise coupling occurs is the substrate. Digital operations cause fluctuations in the underlying substrate voltage, which spreads through the common substrate causing variations in the substrate potential of sensitive devices in the analog section. Similarly, in the case of cross talk between analog nodes, a signal can couple from one node to another via the substrate.This phenomenon is referred to as "substrate coupling" or "substrate noise coupling".
Modelling, analysis, and verification of mixed signal coupling
There is a sizeable literature on substrate, and mixed signal coupling. Some of the most common topics are:
*Differentiating between the random noise inherent to electronic devices and the deterministic noise generated by circuits.
*Examining the physical phenomena responsible for the creation of undesired signals in a digital circuit and the mechanisms of their transport to other parts of the system. The substrate is the most common coupling mechanism, but capacitive coupling, mutual inductance, and coupling through power supplies are also analyzed.
*Comparing various modeling approaches and simulation techniques. There are many possible models for digital noise generation, the substrate impedance network, and the sensitivity of the (unintended) receiver. The chosen techniques significantly influence the speed and accuracy of the analysis.
*Substrate and mixed-signal analysis techniques can be applied to placement and power distribution synthesis.
*"Electronic Design Automation For Integrated Circuits Handbook", by Lavagno, Martin, and Scheffer, ISBN 0-8493-3096-3 A survey of the field of
electronic design automation. This article was derived, with permission, from Chapter 23 of Book 2, "Mixed-Signal Noise Coupling in System-on-Chip Design: Modeling, Analysis, and Validation", by Nishath Verghese and Makoto Nagata
Further reading/External links
[http://www.noisecoupling.com Technical Book: "Noise Coupling in Integrated Circuits: A Practical Approach to Analysis, Modeling, and Suppression", by Cosmin Iorga, Ph.D., 286pages, Hardcover]
Wikimedia Foundation. 2010.
Look at other dictionaries:
Manganese-mediated coupling reactions — are radical coupling reactions between enolizable carbonyl compounds and unsaturated compounds initiated by a manganese(III) salt, typically manganese(III) acetate. Copper(II) acetate is sometimes used as a co oxidant to assist in the oxidation… … Wikipedia
Crosstalk (electronics) — For other uses, see Crosstalk (disambiguation). Not to be confused with Spill (audio). In electronics, crosstalk (XT) is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect… … Wikipedia
Clock feedthrough — In analog electronics, Clock feedthrough is the result of the coupling between control signals on the analog switch and analog signal passing through the switch. In digital electronics, clock feedthrough is the coupling of the clock signal to the … Wikipedia
Mixed-signal integrated circuit — A mixed signal integrated circuit is any integrated circuit that has both analog circuits and digital circuits on a single semiconductor die.    Contents 1 Examples 2 … Wikipedia
Signal integrity — or SI is a measure of the quality of an electrical signal. In digital electronics, a stream of binary values is represented by a voltage (or current) waveform. Over short distances and at low bit rates, a simple conductor can transmit this with… … Wikipedia
Electronic design automation — (EDA) is the category of tools for designing and producing electronic systems ranging from printed circuit boards (PCBs) to integrated circuits. This is sometimes referred to as ECAD (electronic computer aided design) or just CAD. (Printed… … Wikipedia
Electromagnetic field solver — Electromagnetic field solvers (or sometimes just field solvers) are specialized programs that solve (a subset of) Maxwell s equations directly. They form a part of the field of electronic design automation, or EDA, and are commonly used in the… … Wikipedia
Noise margin — In electrical engineering, noise margin is the amount by which a signal exceeds the minimum amount for proper operation. It is commonly used in at least two contexts: In communications system engineering, noise margin is the ratio by which the… … Wikipedia
cell — cell1 cell like, adj. /sel/, n. 1. a small room, as in a convent or prison. 2. any of various small compartments or bounded areas forming part of a whole. 3. a small group acting as a unit within a larger organization: a local cell of the… … Universalium
protein — proteinaceous /proh tee nay sheuhs, tee i nay /, proteinic, proteinous, adj. /proh teen, tee in/, n. 1. Biochem. any of numerous, highly varied organic molecules constituting a large portion of the mass of every life form and necessary in the… … Universalium