Analog to digital converter (ADC) is one of the major building blocks of today’s IC design industry. Rapid evolution of the digital industry puts very high or stringent requirements on the analog and mixed signal design. High demand of system-on-chips (SoC) in almost all applications like wireless communications, mobile communications, consumer electronics and bio-medical electronics, makes the ADC as an important basic building block. Different kinds of ADC architectures are integrating ADCs, Successive approximation Register (SAR) ADCs, Flash ADCs, pipe lined ADCs and sigma delta ADCs. Except sigma delta ADC, remaining ADCs are known as Nyquist rate converters as they follow Nyquist theorem. Sigma delta ADC is known as Oversampling converter as it uses oversampling technique and makes the design of ADC simple by avoiding the anti-aliasing filter requirement. Among all the data converters, sigma delta architecture is most popular for low power and high-resolution applications.
Low power design is always preferred for portable systems as they operate for long time. Sigma delta ADCs are extensively used in biomedical applications, therefore they must operate with low power consumption. For example, pacemakers, which are generally implanted into the human body, should be compact and must operate with minimal power. Apart from the low power requirements, parameter variations cause more problems on analog designs with reduced channel length transistors. Circuits that are designed without considering PVT variations become useless due to their deviated results from the specifications. So, modern circuits must be designed in such a way that they are tolerant to variations and consume less power.
Variations in manufacturing process (P), supply voltage (V) and temperature (T) parameters affect the operation of integrated circuits (ICs) and pose a significant threat to the designers. This problem is severe for analog designs as it includes more number of parameters. Increased process variations make the design of analog blocks more complex. Systems that are designed without taking the PVT variations into consideration, fail to achieve required specifications.
Modern circuit design suffers from escalating power consumption, along with process and temperature variations. Not only dynamic power but also leakage power has emerged as a dominant component of overall power consumption in scaled technologies. Power management techniques magnify the problems associated with process-induced variations. Therefore, designing a process, temperature tolerant circuits with low power consumption is a challenging task.
The prime focus of this book is to design a low power continuous time sigma delta modulator using process (P), voltage (V) and temperature (T) compensated blocks
