Advanced Analog Circuit Design
August 23-27, 2025
EPFL Premises, Lausanne, Switzerland
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Time Assisted Analog Design
Pavan Hanumolu, University of Illinois, USA
Time-based signal processing is emerging as a viable alternative to analog signal processing traditionally performed in voltage, current, or charge domains. This tutorial discusses time-based techniques to implement classical analog functions such as filtering, control and data conversion. Time-based circuits using voltage controlled ring oscillators will be presented and their design tradeoffs will be elucidated with the aid of circuit design examples.
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Analog Building Blocks
Kofi Makinwa, TU Delft, The Netherlands
Analog integrated circuits consist of building blocks with one single or two transistors. The gain, input- and output impedance is analyzed of the three single-transistor stages i.e. the amplifier, the source follower and the cascode. The differential pairs, current source and inverter amplifiers are the most used two-transistor configurations. They are analyzed in detailed. Negative resistors are added for higher Gain and Gain-Bandwidth. Design procedures are discussed for all of them.
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Stability of Operational Amplifiers
Kofi Makinwa, TU Delft, The Netherlands
Two-stage operational amplifiers in unity-gain configuration, suffer from peaking unless a compensation capacitance is added, or the current is increased in the second stage. These stability conditions are examined in detail, followed by five techniques to eliminate the positive zero. One of them is feedforward, which allows a gain of over a factor of two in power efficiency. The design plans are extended to three-stage amplifiers, which offer new stabilization opportunities.
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Noise
Kofi Makinwa, TU Delft, The Netherlands
Abstract.
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Offset and CMRR Limitations
Kofi Makinwa, TU Delft, The Netherlands
Abstract.
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Offset and 1/f Noise Reduction Techniques
Kofi Makinwa, TU Delft, The Netherlands
The design of precision analog interfaces in CMOS is severely impaired by offset, offset drift and 1/f noise. The material covered in this module analyzes these impairments in detail and reviews the common solutions for their remedy: chopping, autozeroing, correlated double sampling and offset stabilization. We will discuss the residual nonidealities as well as pros and cons of each technique and review typical application examples. In addition, we will survey recent advances in the state-of-the-art.
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CMOS Switched-Capacitor Circuit Design
Christian Enz, EPFL, Switzerland
Discrete-time signals, Laplace and z-transform; Basic building blocks (opamps, switches, capacitors); Sample-and-hold circuits; SC integrators, bilinear filters and and biquads; SC amplifiers; Correlated double sampling and chopper stabilization; Nonideal effects and their correction.
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Practical Techniques of Frequency Compensation
Vadim Ivanov, Texas Instruments, USA
Every analog IC comprises multiple feedback loops. Interaction between these loops makes frequency compensation of such system non-trivial task, unsupported by the general control theory. Every MOS or bipolar transistor is nonlinear, which may cause conditional stability and complicate compensation.
We will consider system structure design for stability, needed for it elementary circuit cells additional to the textbook techniques, as well as ways to achieve unconditional system stability when component parameters vary, and when load and signal source impedance is not well defined. Examples include LDOs stable with any load capacitance, transconductors with wide (few volts) input voltage range, and multistage operational amplifiers.
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Bandgap Voltage References
Vadim Ivanov, Texas Instruments, USA
Discussed are error sources of the bandgap voltage references and techniques for improving their accuracy: circuit techniques for low-noise bandgap generation core, feedback amplifier with chopping offset elimination, output buffer with mOhm output impedance and fast settling on load changes; single- dual and triple temperature trimming; packaging requirements; testing and application particulars. Also presented circuit solutions for reverse bandgap reference, operational from 0.9V supply, and reference structure and implementations with nanoampere consumption.
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Techniques for OpAmp Speed and Accuracy Improvement
Vadim Ivanov, Texas Instruments, USA
Presented is a top down design process of the OpAmps based on the structural design methodology. We will start from selection of the gain structure, followed by the implementations of gain structures as well as gradual addition of various specific functions like PSRR/CMRR improvement, slew enhancement, overload recovery. We will consider offset improvement by trimming as well as by auto-zeroing and chopping, high-and low-voltage design specifics. Most of the circuits solutions were not published before and have been used in recent industrial ICs. Yet it is not another cookbook with analog circuit recipes. The goal of this presentation is to arm the engineers with a tool helping to invent the solution for any analog design problem and, at the same time, be reasonably sure that this solution is one of the best possible for any given process and set of constraints.
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Gain Boosting & How to Judge OpAmp Settling Behaviour
Klaas Bult, Analog Design Consult, The Netherlands
Gain-Boosting is a means to enhance the gain of single-stage amplifiers beyond any limit, without degrading the amplifiers speed in terms of GBW or settling behaviour. This lecture discusses how to design a gain-boosting amplifier for optimal settling behaviour and also details the perfect way to judge OpAmp settling behaviour, showing any (start of) ringing (even at the lowest level) or slow settling components, applicable to any type of amplifier.
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Design Mistakes You’d Rather Not Talk About
Klaas Bult, Analog Design Consult, The Netherlands
Every designer makes mistakes and mistakes are not the things we are proudest of, but they are the events that we learn from most. Unfortunately, they almost never get published as only succeses are accepted in Journals and Conferences. This lecture is talking about mistakes I’ve made – and learned from a lot, the hard way.
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Continuous-Time Filters
Christian Enz, EPFL, Switzerland
Continuous-time filters play an important role in many communication systems and at the data conversion interface, where they are required for anti-aliasing and reconstruction. This module begins by reviewing the basic s-domain filter approximations and then looks into implementations strategies. We review active RC and gm-C topologies and study their imperfections and sensitivities to nonideal effects.
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