CICC 1999 Ed Sessions: E-1 - Current Issues in IC Design

Moderator: Douglas Garrity, Motorola
Assistant: Nick van Bavel, Cicada Semiconductor Inc.

E1.1: High-Speed A/D Converter Design

Behzad Razavi, University of California, Los Angeles

8:00am - 9:50am

This tutorial presents the design of high-speed A/D converters from architecture level to circuit level with emphasis on CMOS implementations. Following a review of basic concepts, we describe ADC architectures such as flash, interpolative, folding, two-step, and pipelined topologies. Next, we deal with speed/power trade-offs in the design of the architecture and building blocks. Finally, we study a number of examples of the state of the art.

E1.2: High Speed D/A Converter Design

Doug Mercer, Analog Devices

10:10am - 12:00pm

The tutorial will be presented in three parts:

1) A brief review of D/A basics including a description of the D/A function and the key specifications that define the performance of a D/A

2) A review of common D/A architectures focusing particularly on those that offer the best high speed performance. The advantages and disadvantages of each will discussed.

3) We will conclude with case studies of bipolar, BiCMOS and CMOS implementations.

E1.3: Continuous-Time Sigma-Delta Modulators

Martin Snelgrove and James A. Cherry, Philsar Electronics

1:00pm - 2:50pm

Continuous-time filters have been used in sigma-delta modulator loops both for speed and for resolution, and offer built-in anti-aliasing. They can use active RC, Gm-C, or LC filters, and can combine these with switched-C. Despite the apparent complexity of mixing continuous-time and discrete-time filters in a loop, transfer function design techniques are simple and exact. Second-order effects are subtle, though, when designing these circuits. The designer needs to use ideas from radio circuits to study the effect of clock jitter and filter non-linearity; master/slave or adaptive tuning may be needed; pulse shapes must be kept very consistent; and metastability must be controlled. Diagnosis is difficult, too, because almost all problems produce the same symptom -- in-band noise. All this and more will be covered with analysis, circuit simulations, and examples from the literature.

E1.4: Theory and Design of Crystal Oscillators

Eric Vittoz, CSEM Centre Suisse d'Electronique et de Microtechnique SA

3:10pm - 5:00pm

After describing crystal resonators and their equivalent circuit, this lecture will briefly introduce a general theory of crystal oscillators: how to split the circuit for an accurate analysis including nonlinear effects; condition and frequency of oscillation; start-up time and amplitude limitation mechanisms. It will then focus on the particular but most frequent case of "3-point" oscillators: linear analysis with and without losses; frequency and amplitude of oscillation; elimination of unwanted modes; frequency stability and frequency tuning. Various practical implementations will finally be discussed: grounded drain ("1-pin" oscillator) and grounded sources circuits; bad and good CMOS-inverter oscillators; amplitude limitation and output amplifier.