In recent years, in addition to IoT devices, sensors are being adopted in a wide variety of applications, from wearable and vehicle systems to industrial equipment, to improve functionality and provide advanced control. Used to detect and convert various environmental and physical changes into signals, sensors demand high accuracy, but at the same time, peripheral sensor circuitry is trending toward lower voltages to achieve greater energy savings.
Operational amplifiers are configured in the downstream stage to amplify the output of analog sensors, but because the sensor signals are so weak, noise countermeasures are necessary to ensure high-precision transmission. In response, ROHM has developed a high-noise-tolerance operational amplifier for the automotive market using a vertically integrated production system that leverages original analog design technologies and processes. ROHM has launched an operational amplifier that offers industry-leading performance against external noise, optimized for consumer devices and industrial equipment.
The LMR1802G-LB, developed using ROHM's market-leading analog technology, covers circuit design, processes, and composition, reducing the equivalent noise voltage density by half (2.9nV/√Hz at 1kHz, 7.8nV/√Hz at 10Hz) compared to conventional products, thus significantly improving the detection performance of sensor signals. Furthermore, its best-in-class phase margin (68°) and best-in-class capacitive load tolerance (500pF) provide excellent stability (difficult to oscillate and easy to drive). This enables precise amplification of voltages on the order of µV, ensuring support for applications requiring high-precision detection.
Key Features
1. Easy to use despite the low noise results of the industry's best-performing CMOS op-amps.
This innovative product combines ROHM's superior analog technology, covering circuit design (new circuitry in the differential input stage), composition (analog design studied over many years), and processes (optimized for low noise) to achieve ultra-low noise. The equivalent input noise voltage density of 2.0nV/√Hz at 1kHz and 7.8nV/√Hz at 10Hz is approximately half that of commercially available products, ensuring superior performance with low noise.
Furthermore, in the past, when pursuing lower noise levels in operational amplifiers, problems such as limited phase margin and capacitive load characteristics, as well as oscillations, hampered circuit design. However, the introduction of a new circuit in the differential input stage has enabled ROHM to achieve industry-leading noise levels, along with a class-leading 68° phase margin and a capacitive load tolerance of 500pF.
This doubles the sensing capability of sensor signals compared to conventional solutions, allowing for precise amplification of voltages in the µV range, thus improving performance with sensors that demand higher accuracy.
2. Minimize Input Balance Voltage and Input Bias Current.
In terms of operational amplifier configuration, the output voltage should be 0V when the input is 0V, but a balance voltage is often generated as an error. Furthermore, if the sensor's output impedance is high, the sensor's output voltage will be affected if the operational amplifier's input bias current is large. Therefore, these two error factors must be as small as possible to ensure optimal performance.
The LMR1802G-LB offers an input balance voltage of 450µV and an input bias current of only 0.5pA (4x and 2x less than conventional products, respectively), providing high-precision amplification.
Availability: June 2018 (samples), October 2018 (OEM quantities)
Application Examples
• Distance measuring equipment using sonar and optical sensors
• Security systems, IR remote controls, night vision, and other assemblies equipped with IR sensors
• Devices requiring high-precision operation (e.g., hard drives)
• Equipment management systems, including flow meters and gas detectors
• Other industrial and consumer assemblies integrating sensors that require high-precision detection
Specifications
