COURSE OUTLINE

This course addresses practical circuit analysis, design and layout techniques for successful implementation of various types and applications of on-chip analog filters. The challenge for a novice (or even an experienced) design engineer is the myriad of existing techniques, with all of them promising a great end result. Which approach should I choose? The answer, of course, depends on the situation, and only an in-depth understanding of the various techniques can help in making reasonable architectural and circuit design decisions. The focus of this course, therefore, is on developing intuition for the various techniques, with an in-depth discussion of circuit nonidealities and trade-offs.

The course begins by studying the fundamentals of continuous-time analog filters and the various architectures that one can use to realize them. We will then discuss the trade-offs with each of these architectures and illustrate them with design examples.

Noise considerations are of prime importance in the design of filters. A detailed discussion of noise in electrical circuits and networks with emphasis on filters will be covered.

Filtering using Linear Periodically Time-Varying (LPTV) circuits has received much attention recently. Unfortunately, the available literature in this area is heavy on mathematical details and light on intuition – almost to the extent that it scares designers away. Therefore, a ground-up introduction to LPTV circuits and systems will be presented. No background other than basic signals-and-systems level understanding of the Fourier series, transforms and convolution are needed. The aim is to build intuition and demystify the math.

Knowledge with context is far more powerful. Therefore, in the next lecture, the discussions on LPTV circuits will be illustrated with practical case studies and examples.

N-path filters were first proposed in the 1960’s. Lately they have been rediscovered for being capable of realizing narrow-band, widely-tunable bandpass filter transfer functions. We will first discuss the N-path principle, which is quite general and is a technique that can be applied to an arbitrary LPTV system. Again, traditional treatments of this principle have been in the frequency domain and algebra heavy, burying the designer in a sea of math. This lecture aims to demystify the math, and instead focus on the time-domain intuition behind the principle. Some practical applications of the principle – for example to filters, chopped amplifiers and data-converters – will be covered.

The final lecture of the course is dedicated to practical tips for design, simulation and layout, as well as measurement techniques for some of the sub-systems presented earlier in the course material.

The homework assignments aim to strengthen the intuition developed in the course. The participants may use a circuit simulator of their choice to complete the homework problems.

The target audience for this course are those looking to understand filter design – both time-invariant as well as time-varying. The participants will learn about trade-offs in filter design and the appropriate choice of architecture for their application. A unique aspect of the course is the ground-up introduction to LPTV systems, demystifying these circuits and building intuition.