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Inductor Design
The dream of integrating an entire radio transceiver in a single chip, the so-called radio-on-a-chip, fueled by the wireless revolution, has focused the attention of researchers everywhere on realizing high quality passives in RFIC's and on modeling them accurately. Today's IC designer can...




Circuit Sage Tools
Inductor Q Calculator:
The tool calculates impedance and quality factor of an inductor at a certain frequency
Mutual Inductance between Symmetrical Spiral Inductors:
This tool calculates mutual inductance between two symmetrical spiral inductors.
Simple Analytical Calculation for Spiral Inductors:
This tool calculates inductance for different spiral inductors.


Online Tools


SOFTWARE
AppCAD:
A free tool, which has a spiral inductor designer, matching, and transmission line analysis.
Kansas State's Spiral:
Executables for Windows and Linux available. From their page:"...The program generates a spice sub-circuit which can be used for calculating the different design parameters like inductance (L), quality factor (Q) and self resonant frequency (SRF).."
ASITIC tool for modeling on-chip passives, from UC-Berkeley:
Input a small technology file for your process and it models inductors/capacitors/transformers, outputs SPICE netlist for simulation and CDF file for layout. Runs on Sun/UNIX/Linux
Inductwise and QuickHenry (both FREE) from U. of Wisconsin-Madison:
Inductwise is a fast linear circuit simulator, QuickHenry is an inductance/resistance extraction tool. Both are free.
Interface Technologies' Magnetic Designer for inductors and transformers:
ICAP module can be used stand-alone, email them for pricing
Ansoft's HFSS:
3-D EM solver used by many
Zeland's IE3D:
IE3D is a full-wave, method-of-moments based electromagnetic simulator solving the current distribution on 3D and multilayer structures of general shape.
Agilent's Momentum:
Momentum is a 3-D planar electromagnetic (EM) simulator used for passive circuit analysis


WEB TOOLS
Stanford's spiral inductor calculator tool:
Based on paper referred to in this section's introduction. Calculates inductance values for rectangular, hexagonal, and octagonal spiral inductors.
University of Missouri-Rolla's inductance calculator tool:
Web tool allows user to calculate inductance for various geometries.
COILS tool from Stanford:
For square spiral inductors


Online Articles
Analysis of eddy-current losses of spiral inductors paper from UC - Berkeley:
Equations for eddy-current losses of spiral inductors over conductive substrates are presented and verified against mesaured data of spiral inductors in a 0.25-micron CMOS process.
Simple Accurate Expressions for Planar Spiral Inductances paper from Stanford:
Paper presents 3 simple formulas to characterize spiral inductor structures: rectangular, hexagonal, octagonal, and circular. Compares results with those obtained by a 3-D field solver and with previously published measurements.
Optimizing an inductor using Mathcad presentation from UNCC:
Presents inductor formulas and attempts to optimize a 10-nH inductor using Mathcad
Spiral inductors design wiki from Queens University:
Spiral inductors formulas, parasitic models, and design using tools such as ASITIC and Momentum
Designing spiral inductors with Momentum:
Brief tutorial on using Momentum to design on-chip spiral inductors
Integrated inductors and transformers at 30-GHz and above paper from U. of Toronto:
Demonstrates 50-GHz mixer and 40-GHz VCO in 0.13-um SiGe BiCMOS process using integrated inductors
Modeling and simulation of passive devices on conductive substrates PhD thesis from Berkeley:
Numerical techniques to model on-chip passives are incorporated into the widely-used ASITIC, software that allows to optimize the performance of on-chip inductors and transformers. Demonstrates software with design of 4.4-GHz VCO and distributed amplifier using on-chip inductors.
Patterned ground shields for on-chip spiral inductors: paper from Stanford:
Goes over benefits of patterned ground shields placed underneath on-chip spiral inductors, demonstrates with measurements
Physical modeling of spiral inductors on silicon paper from Stanford:
Scalable physical inductor model for silicon spiral inductors takes into account eddy-current and substrate losses as well as capacitances between the spiral and the substrate and the center tap.
On-chip transformer modelijng for PA's and LNA's thesis from Stanford:
Presents technique to achieve high magnetic coupling and loss insertion loss in on-chip transformers, demonstrates by implementing a PA and an LNA for WLAN applications.
Inductors' physics:
Understanding the physics of inductors, some formulas, lots of pop-ups.
Self-inductance calculations for various structures:
Equations given for common structures
Citeseer:
Over 1 million articles, lots of inductance articles
Interconnect inductance issues in 0.13-um CMOS article from EE Times:
On the difficult task of inductance extraction from a layout.
Steve Long's discrete inductor construction article:
Considerations when building your own inductors
Air coils inductance calculations:
Pros, cons, and equations of air coils
Inductance extraction presentation from U of Wisconsin-Madison:
Concepts and equations related to extracting inductance from IC layouts
Inductance equations from RF Cafe:
Equations for 4 structures and basic circuit stuff
Spiral Inductors and Transformers for silicon RFIC's paper from UC - Berkeley:
Presents EM-based method to analyze and optimize integrated spiral inductors and transformers, introduces ASITIC tool
ASITIC presentation:
Describes ASITIC methodology and performance capabilities


Books
Lumped Elements for RF and Microwave Circuits by I.J. Bahl:
From description:"...offers an in-depth understanding of the different types of RF and microwave circuit elements, including inductors, capacitors, resistors, transformers, via holes, airbridges and crossovers. Supported with over 220 equations and more than 200 illustrations, it covers the practical aspects of each element in detail...."
Inductance Calculations by F. Grover:
Very good reviews at Amazon. His formulas are quoted everywhere. From description:"...Hoping to simplify matters for engineers overwhelmed by inductance calculations, the author brings together an invaluable collection of formulas and tables. For virtually every type of inductor, Dr. Grover provides a single simple formula, together with tables from which essential numerical factors may be interpolated...."
Design, Simulation and Applications of Inductors and Transformers for Si RF ICs by A. Niknejad and R. Meyer:
From description:"...provides a deep understanding of the physics involved in the operation of these devices at microwave frequencies. Additionally, the book tackles two critical blocks that depend critically on the passive devices, the voltage-controlled oscillator and a distributed amplifier. ..."