| 摘要 |
A method and apparatus for improving the AC common mode rejection performance of monolithic two op-amp instrumentation amplifiers is disclosed. A new approach to designing the first op-amp of an instrumentation amplifier is provided wherein the frequency of the first op-amp is manipulated such that the dominant pole is pushed out to higher frequencies than is possible using traditional methods while maintaining good open loop gain and closed loop stability. One way to achieve this is by designing the first op-amp such that it has two dominant, low frequency poles and a higher frequency zero to provide stability. With this design of a first op-amp, the range of high common mode rejection ratio is extended to frequencies an order of magnitude higher than achievable by conventional means without additional requirements for bandwidth, power or die area. Utilizing this principle makes it possible to design small, low power, two op-amp instrumentation amplifiers that can reject line noise and its harmonics, tasks that previously required three op-amp architectures or hundreds of megahertz bandwidth.
|
