Supplier eBooks

article explores how low power op-amps allow the successful deployment on always ON sensors in the field. Sensors Here, There, and Everywhere Why are there so many sensors showing up in just about any application you can think of? It is because as human beings we want more information so we can better control and manipulate things to our advantage, and flourish. Sensors provide a way for us to collect information about our external world in the form of an analog electronic signal. A variety of electronic sensors may be employed to collect analog information. These include: • Temperature sensors Provide smart thermal monitoring with high-accuracy, low-power • mmWave sensors Rapidly and accurately sense range, angle, and velocity • Magnetic sensors Durable and reliable operation, simple, often used for position-sensing • Humidity sensors Humidity and temperature monitoring • Specialty sensors Ultrasonic, ambient light, time-of-flight (TOF) Ideal sensors consume low power and are accurate in response to the items they are measuring and responding to. Before the collected sensed analog signal might be sent on to be digitized and processed further, it is usually necessary to increase and make the collected signal stronger, making further discernment and screening of the analog signal easier. External conditions that are not desirable for further processing gets controlled through electronic filtering, a process whereby their signal strength may get degraded or ignored, while the desired signal gets boosted through amplification. Such a process improves the signal-to-noise ratio (SNR) of the analog information, allowing further steps in signal conditioning to be performed to shape the signal before manipulation into the digital domain whereby it undergoes processing. Operational amplifiers are used to boost the sensor's signal level. Ideal op-amp performance is impossible. However, semiconductor companies like Texas Instruments invest a great deal of design effort to tailor their designs so that the greatest ideal op-amp performance for the application gets realized. Ideal op-amps characteristics generally include: Gain 0–∞ Impedance, Input (ZIN) ∞ Impedance, Output (ZOUT) 0 Noise 0 Offset, Output (VO) 0VDC, when inputs grounded Bandwidth (BW) ∞ High Precision Earlier it was stated that two key characteristics of op-amps necessarily optimized for always ON sensing applications were (1) precision and (2) low power. Let's examine the first of these two characteristics—precision. The International Organization for Standards in ISO: 5725- 1:1994 entitled Accuracy (Trueness and Precision) of Measurement Methods and Results–Part 1: General Principle and Definitions defines precision as the repeatability or reproducibility of the measurement. It is a measure of how 5 Figure 1: Texas Instruments LPV821 Zero-Drift Nanopower Operational Amplifier. (Source: Mouser Electronics) LPV821 Zero-Drift Nano-power Amplifier • Quiescent Current: 650nA • Low Offset Voltage: ±10µV (Maximum) • Offset Voltage Drift: ±0.096µV/°C (Maximum) Learn more

• Cover