A practical overview of CMOS circuit design, this book covers the technology, analysis, and design techniques of voltage reference circuits. The design requirements covered follow modern CMOS processes, with an emphasis on low power, low voltage, and low temperature coefficient voltage reference design. Dedicating a chapter to each stage of the design process, the authors have organized the content to give readers the tools they need to implement the technologies themselves. Readers will gain an understanding of device characteristics, the practical considerations behind circuit topology, and potential problems with each type of circuit. Many design examples are used throughout, most of which have been tested with silicon implementation or employed in real-world products. This ensures that the material presented relevant to both students studying the topic as well as readers requiring a practical viewpoint. Covers CMOS voltage reference circuit design, from the basics through to advanced topics Provides an overview of basic device physics and different building blocks of voltage reference designs Features real-world examples based on actual silicon implementation Includes analytical exercises, simulation exercises, and silicon layout exercises, giving readers guidance and design layout experience for voltage reference circuits Solution manual available to instructors from the book’s companion website This book is highly useful for graduate students in VLSI design, as well as practicing analog engineers and IC design professionals. Advanced undergraduates preparing for further study in VLSI will also find this book a helpful companion text.

A traditional bandgap reference voltage has a value approximately equal to 1.2V. This is an inconvenient value to obtain in short-channel CMOS circuits where the nominal power supply voltage is 1.2V or lower. Here, a simple circuit is presented to generate a reference voltage between 600mV and 800mV, based on the threshold voltage of a MOS device, which will be suitable for biasing transistors in strong inversion as well as for use in 6-bit data converters needed for high speed data communication systems. The circuit uses a novel, but simple, method for generating the temperature coefficients needed for generating a stable voltage reference across temperature. The core circuit produces a PTAT current that when passed through a diode-connected device, with a CTAT threshold voltage, will produce a voltage that is stable across temperature. The measured results demonstrate an average voltage variation of 4.62mV across five chips, each containing eight voltage reference circuits, and a minimum voltage variation of 1.1mV from 0°C to 80°C. A variation of the proposed circuit replaces the BJTs with MOSFETs to achieve smaller area, and simulation results indicate even less voltage variation across temperature.

Voltage references are fundamental to mixed signal converters which are widely used in elec- tronics. Hence there are signicant advantages in having the voltage reference operate with less power while minimizing area consumption and maintaining performance. Past designs have suered from issues related to process variations which adversely aect the temperature coe- cient of the circuit output. To compensate for these process variations, a means to modify the temperature coecient are proposed and experimentally veried with two circuit architectures. Five test chip samples implement these architectures in a 0.35 m CMOS process. Design methodologies for both architectures are presented. Design techniques include the use of a high-swing cascode to improve Line Sensitivity while minimizing additional power consumption, accounting for a well-matched layout, and the eect of leakage currents on the performance of the circuit. Layout schematics, performance gures, test methodologies and results are presented. Each circuit dissipates less than 4 nW and operates down to 0.9 V or better with Line Sensitivity and Power Supply Rejection Ratio of less than 0.15 %/V and -58 dB respectively, while consuming an area of 0.053 mm2 or less. The experimental average and median temperature coecient was less than 26 ppm/C and 22 ppm/C respectively in the #x0;20 C to 80 C range, with the best performance being less than 8.1 ppm/C. Areas of improvement and potential areas of future research are then identied to facilitate advancement of this work.

Voltage references represent important VLSI structures, having multiple appli- tions in analog and mixed-signal circuits: measurement equipment, voltage re- lators, temperature sensors, data acquisition systems, memories, or AD and DA converters. Operating as a subcircuit in a complex system, an important requi- ment for this class of circuits is represented by the possibility of implementation in the existing technology, using the available active and passive devices. The most important performances of a voltage reference circuit are represented by temperature behavior, power supply rejection ratio, transient response and, for the latest designs, by low-power low-voltage operation. Depending on the load - quirements, the output of the circuit can be regulated or unregulated. In order to reduce the sensitivity of the reference voltage with respect to the supply voltage variations, modi?ed cascode structures can be implemented, a trade-off between line regulation and low-voltage operation being necessary in this case. A large bandwidth of the voltage reference improves the transient behavior of the circuit, implying also a good noise rejection. Referringtothe possibilities ofimplementinga voltagereferencecircuit,two d- ferent approaches could be identi?ed: voltage-mode and current-mode topologies, being also possible to design a mixed-mode voltage reference.