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Voltage References
The performance of most circuit blocks in an SoC is tied to that of the voltage references used to bias and power them. Therefore, bandgap references (BGR's), Low-Dropout Regulators (LDO's), and switching DC-DC converters play a crucial role in the performance of large ICs (SoCs). It is im...




Circuit Sage Tools
*Extensive* Mathcad routine to design integrated bandgap circuits:
Basic BG equations, stability, noise, PSRR, startup circuits
*Extensive* Mathcad routine to design integrated bandgap circuits in pdf:
.pdf of integrated bandgap circuit Mathcad routine
Simple Bandgap Design Tool:
This tool calculates different circuit element values needed in a design a simple bandgap circuit.


Online Tools
TI's SwitcherPro:
Online tool to help design power supplies using TI's IC's
Linear Tech's SwitcherCAD:
Tool to simulate switching regulators


Online Articles


BANDGAPS
Bandgap presentation from Infineon:
Bandgap principles and sources of error
Low-voltage bandgaps presentation from U. of Toronto:
Overview of low-voltage bandpap topologies that have been presented in the past
Bandgap reference voltage shifts introduced by package: paper from Georgia Tech:
Analyzes systematic voltage shifts introduced by encapsulation of the IC bandgap. Proposes 15-um thick elastic layer between package and die to mitigate package effects.
Bob Pease's tutorial on bandgaps and techniques to avoid common problems:
Scroll down. Good checklist of things to look out for. Layout issues, oscillations, DC and tempco errors, start-up circuit errors.
IC Bandgap lecture from Georgia Tech:
Develops Vbe and Vth tempco's, presents basic bandgap topologies
Advanced IC Bandgap lecture from Georgia Tech:
Presents bandgap circuits to achieve very low tempco's
Bandgap resistant to radiation paper from U. of Twente:
Analysis of radiation effects in MOS transistors and diodes, implements radiation-tolerant CMOS BG in 0.13-um process
Overview of advanced bandgap ciruit topologies paper from Hong Kong University of Science and Technology:
Very good overview of sub-1V and curvature-corrected bandgap circuits.
Bandgap thesis from Georgia Tech:
Examines sources of error in bandgap references. Develops trim-less, high-PSRR, low-voltage bandgap reference, achieves <1% 3-sigma variation, PSRR ~ -30 dB.
Analysis of sources of errors in bandgap circuits paper from Georgia Tech:
Good paper analyzes the sources of error in bandgap circuits, shows which are the most significant, backs with measured data.
Sub-1V, curvature-corrected bandgap thesis from Linkoping U. in Sweden:
Interesting BG topology fabricated in 0.18-um CMOS, works for 0.9-1.5 V Vdd, 0-60 C temp range and draws only 5 uA from the supply. Temp variation of 7 ppm
Packaging Effects on Bandgaps thesis from MIT:
Very good. Investigates effects of mechanical stress introduced by packaging on the electrical performance of BG's, both the distribution at room temp and tempco variation from part to part. Characterizes Linear Tech's stress-relief technique to ameliorate stress issues.
IRF paper on sample-and-hold technique to address offset compensation:
Achieves 12 ppm/C TC, implemented in 0.35-micron CMOS although no measured data is presented


DC-DC CONVERTERS
Buck converter uisng 2-nH integrated spiral inductors paper from U. of Minnesota:
Takes advantage of on-chip magnetic coupling by stacking spiral inductors, demonstrates with 0.13-um CMOS buck converter that achieves 70%+ efficiency at 0.9-V output.
Hysteretic buck converter with fast response for DVS applications paper from HKUST:
Targeting Dynamic Voltage Scheduling applications, the converter can generate 0.5V-2.5V outputs from a 3-V supply. Has constant switching frequency of 850 kHz and a 12.5-us/V response time for an output voltage change. Implemented in 0.35-um CMOS.
DC-DC presentations from U. of Colorado:
16 presentations on DC-DC converters from a University of Colorado course, very good.
Lecture notes from U. of Colorado course:
Presentations on resonant and soft-switching DC-DC's, a lot of good information.
High-voltage, low-noise DC-DC's app note from Linear:
Applications that require a few hundred volts output voltage
Overview of switching-loss reduction methods for buck converters paper from HKUST:
Analysis of switching-loss reduction approaches that have been proposed recently
Switched-capacitor voltage doubler paper from HKUST:
150-mA SC voltage doubler implemented in 0.6-um CMOS
Current sensors for DC-DC converters paper from HKUST:
Fast, low-quiescent current sensor introduced and implemented in 0.35-um CMOS
DC-DC converters thesis from HKUST:
Introduces Single-Inductor, Multiple-Ouput (SIMO) converter class for VLSI power management, topologies for their control and regulation, addresses cross-regulation issues in multiple-ouput converters. Implements 3 DC-DC's in 0.5-um CMOS. MATLAB routines included in Appendix.


LINEAR REGULATORS
TI's Review of LDO's:
Very good review of performance metrics and issues that affect the performance of LDO's, including capacitor ESR and the stability "tunnel of death". Good stuff.
PMOS LDO analysis from TI:
PMOS LDO topology and analysis of LDO transient sequence in the event of a sudden load change
TI's Understanding LDO Dropout Application Report:
How to extrapolate data-sheet dropout data for a given application.
Power supply integrity in large IC's presentation from Stanford:
Introduces circuits to accurately measure supply noise on large IC's and push-pull regulator topology for efficient, quiet on-chip regulation
Reducing the PSRR of LDO's for PLL's paper from Stanford:
Analyzes LDO PSRR trade-offs, proposes new LDO compensation scheme to achieve increased PSRR
Design methodology for LDO's paper from Hong Kong University of Science and Technology:
Approach attempts to minimiza area of power transistor as wells reduce the LDO quiescent current
Area-efficient LDO compensation scheme paper from HKUST:
Approach to reduce comp. cap. for on-chip LDO's, implements LDO in 0.35-um CMOS, stable under min/max loads of 100-uA/100-mA.
50-mA, very-low-Iq LDO paper from HKUST:
LDO with 1-uA iq uses high-slew-rate push-pull output error amplifier stage for fast transient response to load changes. Implemented in 0.18-um CMOS
Analysis of PSRR in LDO's paper from Georgia Tech:
Detailed analysis of PSRR in LDO's, backed by measured data.
Professor Gabriel Rincon-Mora's list of publications and articles:
Very good resource. Many articles on IC bandgaps, linear regulators, and DC-DC converters
Power Supply Noise Reduction paper:
Bypassing and decoupling techniques in order to get clean supply voltages
TI's LDO and DC-DC application reports:
A couple of hundred of app notes on LDO's, DC-DC's, and power management
Maxim-IC's Voltage References application notes:
About 20 of them, some of them don't seem related to voltage references.
CiteSeer:
Great research resource, lots of papers
Linear power app notes:
Linear regulators and DC-DC converters app notes
Decoupling and grounding application note from ADI's Paul Brokaw:
Techniques for decoupling and grounding. If this link breaks look for AN-202 in ADI's website.
Grounding for low- and high-frequency circuits:
Practices to avoid and techniques for effective grounding. Should this link break look for AN-345 on ADI's website.
Switched decoupling capacitor technique presentation from U. of Minnesota:
Senses supply voltage noise level and utilizes capacitors that can be re-arranged with switches to react accordingly


Books
Grounding and shielding techniques two-day course from U. of Missouri-Rolla:
I think they can send them to you in VHS format. Many people have taken this course.
Voltage References: From Diodes to Precision High-Order Bandgap Circuits by Gabriel Rincon-Mora:
Higher-order bandgap references that cancel second and third order tempco's. Probably best for people that have had some experience in BG's already.
Design of Analog CMOS Integrated Circuits by Behzad Razavi:
Very good chapter on BG's (chapter 11) and good book to have anyway
Fundamentals of Power Electronics (Second Edition) by Dragan Maksimovic and Robert Erickson:
Very enthusiastic reviews on Amazon, seems like THE book to have handy if you are entrusted with a DC-DC converter design
Switching Power Supply Design, 3rd Ed. by Abraham Pressman:
Extremely enthusiastic reviews on Amazon.