CMOS op-amp lowers noise levels for accurate optical sensors

For applications that demand high-accuracy sensing, including sonar and optical sensors, Rohm has introduces a CMOS op-amp claimed to feature the lowest noise in the industry. The LMR1802G-LB is optimised for applications requiring high-accuracy sensing, such as accelerometers used in sonar systems, and optical sensors that handle ultra-small signals.

Rohm reports that sensors are being adopted in a variety of applications, far beyone IoT applications, from portables and vehicle systems to industrial equipment, to improve functionality and provide advanced control. They are used to detect and convert various environmental and physical changes into signals. Sensors demand high accuracy, but Rohm has identified that peripheral sensor circuitry shows a trends towards lower voltages to achieve greater power savings.

Op-amps are configured at the rear stage to amplify the analogue sensor output, but because sensor signals are so weak it is necessary to implement noise counter measures to ensure high-accuracy transmission. In response, Rohm developed a high noise tolerant op-amp for the automotive market using a vertically integrated production system that leverages original analogue design technologies and processes. Rohm has introduced an op-amp that delivers the industry’s best performance against external noise optimised for consumer devices and industrial equipment.

The LMR1802G-LB has been developed using Rohm’s market-leading analogue technology covering circuit design, processes, and layout. The technology halves input equivalent noise voltage density (2.9nV/√Hz at 1kHz, 7.8nV/√Hz at 10Hz) compared to conventional products. This improves the detection performance of sensor signals, reports Rohm. In addition, best-in-class phase margin (68 degree) and capacitive load tolerance (500pF) are claimed to provide “excellent” stability (difficult to oscillate, easy to handle). This enables accurate amplification of voltages in the order of µV, ensuring support for applications requiring high-precision sensing.

Typical applications are distance measuring equipment, using sonar and optical sensors, security systems, IR remote controls, night visions and other sets equipped with IR sensors. It can also be used in equipment management systems, including flow meters and gas detectors.

The LMR1802G-LB has been sampling since June and OEM quantities are expected in October 2018.

http://www.rohm.com/eu