If you’re using a high-resolution (16- and 18-bit) successive-approximation-register (SAR) analog-to-digital converter (ADC) in your design, you’ve probably faced the challenge of finding the best possible amplifier to drive it.
One of the most common challenges is maintaining a low noise floor without having a horrendous power budget in the analog front-end. In other words, the only way to get a low noise floor is to pump large amounts of current into the operational amplifier (op amp). Integrated circuit (IC) designers may also need to use bulky transistors in the input topology, which limits their ability to use a small footprint and adds substantial cost due to the die-size increase.
What if you could have a scalable amplifier in the front-end? I’m talking about a device that combines a high-power mode, a low noise floor (2.5nV/rtHz), a superb settling time (200ns for 0.0015% off a 4V step) and a low-power mode such that the op amp only draws about 0.25mA of quiescent current. This would be a “turbo amp” like the OPA625.
The OPA625 can be used in high-power mode while the ADC is in acquisition mode, thereby enabling enough bandwidth, slew rate and current for its output to settle quickly, as well as a noise floor low enough to maintain the optimal system effective number of bits.
The scalability, low offset voltage and low drift aspects of such an op amp offer a clear advantage over its high-speed counterparts. Its low distortion also helps maintain signal integrity.
With a wide bandwidth and low quiescent current, it offers high performance in AC and DC wise.
Because the OPA625 is built on a complementary metal-oxide semiconductor (CMOS) process, it is versatile and can be used in a broad range of applications. The combination of low voltage and current noise makes it beneficial for interfacing high-impedance sensors, such as piezoelectric and passive infrared (PIR).
So the next time you’re looking to keep your noise under control, give the OPA625 a shot, and get your circuit to quiet down without burning holes in your printed circuit board (PCB).
What application would you use this turbo amp for?
Related technical resources:
- Download the OPA625 datasheet.
- Sample the OPA625
- Read more of my precision op amp blogs.
- Learn more about amplifiers by downloading the Best of Baker’s Best - Amplifier e-book by my colleague and EDN columnist Bonnie Baker.