I wrote an article appearing in this month’s Analog Dialogue that shows how compensating an amplifier—such as the ADA4895-2, which is normally stable for a gain higher than +9— to operate with a gain as low as +2, provides higher slew rate and faster settling time than an equivalent internally compensated amplifier. Two methods were presented, one adds an RC circuit  from the inverting input to ground whereas the second adds a  resistor between the inverting and non-inverting inputs. Finally advantages and disadvantages of each circuit were highlighted.


The ADA4895-1/ADA4895-2, part of the ADA4896-2/ADA4897-1/ADA4897-2 family, are low-noise, high-speed, voltage-feedback amplifiers with rail-to-rail outputs. Stable with a minimum gain of 10, they feature 1.5-GHz gain-bandwidth product, 940-V/μs slew rate, 26-ns settling time to 0.1%, 2-nV/√ Hz 1/f noise at 10 Hz, 1-nV/√ Hz wide band noise, and −72-dBc spurious-free dynamic range at 2 MHz. Operating with a 3-V to 10-V supply, they draw a quiescent current of 3 mA per amplifier.


Read the full article titled Compensating Amplifiers that are Stable at Gain ≥ 10 for Lower Gain Operation.



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