opa-design_slide外文电子书.pdf

Design of OP-AMPS 1 Outline I. General Consideration II. Two-Stage CMOS Op-Amp III. Cascode Op-Amp IV. Folded-Cascode Op-Amp V. Current-Mirror Op-Amp VI. Fully Di erential Op-Amp VII. Common-Mode Feedback Circuit VIII. Rail-to-Rail Op-Amp IX. Conclusion 2 I. General Consideration *We loosely defined an op-amp as a “high-gain differential amplifier.” *Up to two decades ago, most op amps were serve as “general-purpose” building blocks, satisfying the requirements of many di erent applications. Such e orts sought to create an “ideal” op amp, e.g., with very high voltage gain, high input impedance, and low output impedance, but at the cost of many other aspects of the performance, e.g., speed, output voltage swings, and power dissipation. *By contrast, today’s op amp design proceeds with the recognition that the trade-offs between the parameters eventually require a multi-dimensional compromise in the overall implementation, making it necessary to know the adequate value that must be achieved for each parameter. 3 II.Two-Stage Op-amp C cmp V -A2 1 V in A1 out Di erential Second Output input stage gain stage bu er (i) The first gain stage is a di erential- input single-ended output stage A ⇑ (ii) The second gain stage is normally a