Arie van Staveren

Dynamic translinear circuits

A promising new approach to shorten the design trajectory of analog integrated circuits without giving up functionality is formed by the class of dynamic translinear circuits. This paper presents a structured design method for this young, yet rapidly developing, circuit paradigm. As a design example, a 1-V 1.6-μA class-AB translinear sinh integrator for audio filter applications, is presented.

BANDGAP REFERENCE DESIGN

For many years bandgap references have been used as voltage references in various fields of application; for instance, in DA converters [1], automotive industry [2] or battery-operated DRAMs [3]. All of the bandgap references used in this diverse variety of applications are based on the idea of Hilbiber in 1964 [4]. After his publication, a vast number of articles appeared describing other topologies and components being used [5–11]. In this chapter, a structured design method is presented which structures the knowledge gained in the past decades concerning bandgap reference design and from that an extrapolation is made. Explicit relations are derived between, for instance, the noise level and the current consumption. In this way existing trade-offs are made explicit. To get a clear insight into the bandgap reference to be synthesized, first a general description is given of a bandgap reference, see Section 5.2. The base– emitter junction is used as the core element for bandgap references. Section 5.3 describes its temperature behavior. Subsequently, Section 5.4 describes in general terms the temperature compensation of the base–emitter voltage in order to approximate a temperature independent voltage. It is shown that the general bandgap reference can be described by a linear combination of base–emitter voltages. This linear combination is used as a high-level description for temperature compensation, Section 5.5. From this description, the key parameters for bandgap reference design are derived in Section 5.6. Then, as the basic structure of the bandgap reference is found, the influence of the temperature dependency of resistors can be described at a high level of abstraction, Section 5.7. Section 5.8 describes the trade-off between the noise level and the current consumption. From the high-level description of the bandgap reference, found in Section 5.4, simplification can be made leading to some specific structures with nice properties, see Section 5.9. Section 5.10 shows in an overview two design examples. Finally, conclusion for this chapter is given in Section 5.11.

An automated grade prediction system

At the end of a lecturing period examinations are used to take a snapshot of the level of knowledge of a student. It is essential that this snapshot be taken at the right moment. Particularly when a student fails, it is important to make sure that it is because his level of knowledge is not adequate, not because, for example, he had a severe headache, was blocked by examination stress or misread the questions. Even when a student does pass, it may be that the grade is too low because of unjust causes. The system presented in this paper is designed to prevent this situation. An automated Internet-based system makes multiple-choice tests available for students of which the contents depend on the date. It tracks the actual course content. When a student does a test, the system will grade the student and predict the official grade that can be expected at the final examination. The results of the final examination are compared with the prediction. When the prediction is higher than the actual grade, the cause is investigated and possibly an extra assessment is done. The system is completely automated and is available for students 24 h per day. This makes sure that the snapshot is taken at the right time, since the student himself can decide when to take a test. The system does not officially grade the students and is therefore not very sensitive to fraud, but it efficiently removes the ‘snapshot risk’ of the official exam, resulting in a much better quality of the grading process

Structured Oscillator Design

This paper presents a general design approach applied to the design of oscillators. The design approach is based on classification of oscillator circuits. From this classification rules for designing oscillators can be extracted. These design rules are used as a fast means to get to an overview of the design space and to focus the creativity of the designer to the spot where the real design challenge is. The structured oscillator design approach has led to insight such that new circuits where found. The key ideas in these circuits are also presented.