Analog Devices has a large portfolio of in amps in chip form to choose from. However, in the previous slides it was shown that an “in amp” can also be built discretely, using a few op amps and resistors. What are the pros and cons of each? When customers buy an instrumentation amp as one monolithic integrated circuit, they get several advantages. One advantage is that users draw on the experience of IC designers that are dedicated to working on instrumentation amplifiers and have many years of experience doing so. Because of their experience, they typically know many tricks to get the last bit of performance out of the instrumentation amplifier. Because these designers operate at the IC level, they can optimize the circuit in ways not available to the board level designer: for example, they can arrange the layout of the two preamps symmetrically so they match very well and can trim their output power, since they know these amplifiers will only drive a light load. If all of the instrumentation amplifier is contained in one chip, board parasitics have little effect. The solution is also smaller. Finally, semiconductor manufacturers like Analog Devices have the ability to trim internal resistors inside the chip. This allows correction for non-idealities and mismatches in the original circuits. Chief among the benefits of trimming is getting very precisely matched resistors, which gives excellent CMRR performance. To get similarly matched resistors on the open market is very costly. There are occasionally advantages to building a design discretely. Unlike the IC designer, the board designer knows exactly what parameters are important for the application, and can optimize the instrumentation amp to fit exactly the application. A discrete design also allows access to all nodes in the instrumentation amp design, which may be useful for filtering or if the internal nodes have useful information for other parts of the design.