Basic Analog Circuit Design

Abstract

In this chapter, we have discussed the basic building blocks for data converters including opamps, voltage and current comparators, reference generators, and reference buffers. For high-performance SC data converters, the telescopic opamp with the SC CMFB is the recommended top choice since it is most power-efficient, least noisy, and fastest. To boost the gain, the gain-boosting technique is recommended. For voltage comparators, the best choice is the positive-feedback latch preceded by low-gain preamplifier( amplifier(s). When a low-offset is needed, auto-zeroing is recommended. The key to high-performance current comparator is the low-input impedance such that current sources having high output impedance can directly drive it. A complete data converter needs on-chip band-gap reference using the parasitic PNP transistors. With a high-accuracy voltage generated on-chip, we can derive an accurate current by resorting to an external precision resistor. To buffer the voltage reference for high performance data converters, we recommend a large external capacitor.