(Source: Analog Devices)
No matter how fast and powerful your DSP blocks can perform, it means nothing if you can't get a clean, accurate, low-drift signal chain into your front-end analog to digital (A/D) converters. Obtaining and maintaining the analog signal chain from outlying sensors and transducers with low noise, distortion, and drift requires a precision signal chain. High-resolution A/D converters often use analog switches to multiplex linear signals from different locations within a system's board. Each signal chain routing to the multiplexer must be precise for the highest performance and reliability.
A precision signal chain combines design practices and component selections to ensure analog signals can route from remote point sources—such as sensors—to a centralized or multiplexed processor unit. Analog signals are operated upon as stages of a signal chain, with the output of one stage feeding the input of the next stage. Each stage performs functions like filtering, surge protection, attenuation, amplification, inversion, phase shift, and more.
Portable and battery-powered equipment designers have power and energy management constraints that require precision signal chains at lower voltage and current levels. Precision current sensing signal chains used in high-resolution A/D converters, motor control, and energy management need robust filtering and noise immunities.
Other precision signal chain applications include isolated gate drives and high voltage and current power control sensors. Isolated drivers are often used to protect sensitive circuitry and to maintain low noise levels for accurate measurements. Sense amplifier signal chains are essential to accurately measure the switch's current flow.
While any analog system can have a signal chain, Analog Devices (ADI) refines the precision signal chain to mandate that time and temperature drift are minimized, power consumption is optimized, distortions are very low, and signal quality is maintained throughout the analog circuitry.
Operational amplifiers (Op-Amps) are vital to implementing and optimizing precision signal chains. To reduce noise, amplification is as close to a sensor or transducer as possible. This can be voltage or current gain, or both. The important thing is to increase the signal-to-noise ratio so that noise has a minimized effect on the precision signal chain.
Critical parameters like input offset voltages (Vos) need to be low. These differential levels between the inverting and non-inverting inputs of the Op-Amp can introduce increasing error levels as higher gain amplifier stages are used. These levels can also grow with increased temperature (ΔVOS/ΔT). Although such offsets can be compensated for by using external components, the additional compensation potentially adds cost, increases size, and affects long-term reliability due to decreased mean time between failures (MTBF). With this in mind, an Op-Amp selection that has intrinsic low input offset voltages is critical.
While input offset voltages can saturate an Op-Amp at high gain levels, high noise levels can cause AC noise to ride upon the desired signals. A quiet Op-Amp has a very small noise floor, typically less than 10nV/√Hz, which allows signals to be more precise without noise riding on the sensed signal. One solution that offers this precision is the ADA4510, which has excellent low noise specifications of 5nV/√Hz (typical at 1KHz), making it significantly quieter than the typical threshold.
Not all precision signal chains require high speed, but many do. In such cases, fast slew rates are essential to avoid distorting rise and fall signal times. The ADA4510 is well-suited for these applications, featuring a high slew rate of 19V/μs and a wide gain-bandwidth product of 10.4MHz. Its robust output circuitry ensures minimal distortion, making it an ideal choice for high-speed precision signal chains.
In sensitive analog signal chains, a wide temperature range with temperature compensation is essential for maintaining precision. The ADA4510, with its wide specified temperature range of -40°C to +125°C, ensures stability and accuracy in such environments. Additionally, in applications involving multiplexed signal routing, the precision of the analog switches and the consideration of voltage drops are critical for maintaining signal integrity (Figure 1).
Figure 1: Maintaining precision for sensitive analog signal chains requires high-performance Op-Amps with low noise, low offsets, and consistency phase response. (Source: Analog Devices)
For small and portable designs, a key requirement is circuit density. Dual and quad channel devices offer higher circuit densities. To further enhance precision, small packages can also help shoehorn the Op-Amps into tight spaces for reduced signal noise and distortion downstream.
ADI has long led linear and mixed-signal component design and manufacturing. As an industry leader, ADI has pioneered and refined the precision signal chain with advanced new parts to help implement high-quality, resolute, and clean analog signals and systems.
The ADI ADA4510 boasts best-in-class low offset drift specifications, maintaining a typical offset voltage drift of only +/-0.12 microvolts per degree Celsius. This low temperature-induced drift is essential for high-precision applications. Additionally, the ADA4510 features low offset voltage, typically +/-5 microvolts at 25°C, ensuring minimal variation in performance due to temperature changes.
To help evaluate and prototype rapidly, ADI provides the EVAL-ADA4510-2ARZ board, providing easy access to inputs and outputs and operating over the entire 40V Vcc range (Figure 2). Bias and gain resistors and capacitor footprints are easily accessible and can be tailored for your specific design. Power tabs for dual or single rail designs are provided, and input protections are in place.
Figure 2: The highly flexible evaluation board for the ADA4510 has independent Channel A and Channel B configurable circuit paths and grounding options to help rapidly prototype your designs. (Source: Analog Devices)
A vital factor for choosing the ADA4510 is the low noise characteristics. For slow-moving analog signals like temperature, pressure, and humidity measurements, the ADA4510 has a sweet spot of 1 microvolt peak-to-peak noise at ambient temperatures from 0.1Hz to 10Hz.
ADA4510's input impedances of 1 and 10 Tera-Ohms for differential and common mode configurations minimize loading on the signal source, preserving signal integrity. Its low bias current of less than 10pA at ambient temperatures reduces error, ensuring accurate measurements in high-precision applications. Additionally, its high slew rate of 19V/µs can handle rapid changes in signal, avoiding distortion and maintaining signal fidelity. ADA4510's 10.4MHz gain bandwidth ensures optimal working conditions in a wide range of frequencies without significant loss, which is crucial for applications requiring broad frequency response. Last but not least, the ADA4510’s Dynamic performance and recovery time of up to 2.4GHz, indicate its capability to recover quickly from transients, maintaining performance stability in high-frequency environments.
The key is the 40V rail-to-rail operating range. This can be single rail 40V or dual rail +/- 20V with input differential voltage tolerances up to +/-45V. This makes the ADA4510 suited for precision high voltage signal chains that are useful in electric vehicle battery monitoring and precision monitoring of charging voltages and currents. The thermally limited output short circuit protection helps safeguard the part and circuitry during extreme conditions. It can withstand +/- 1000V electrostatic discharge (ESD) in accordance with the human body model (HBM).
Furthermore, the ADA4510 offers two Op-Amps in the small outline 8-lead SOIC_N package, and features 'No Phase Reversal' characteristics between inputs and outputs, which is essential for phase-sensitive applications (Figure 3).
Figure 3: A vital feature of the ADA4510 is that there is no phase shift or reversal from rail-to-rail input to output, helping to tighten up accuracy and response time for phase-sensitive designs. (Source: Analog Devices)
Analog circuit design is an art unto itself, and when combined with digital circuitry in a mixed signal design, it requires some finesse and effort. Once the requirements and design approach are nailed down, the proper selection of components makes all the difference. Here, trusted and accomplished manufacturers can provide the specifications and details needed to succeed.
The ADA4510 from Analog Devices features excellent DC precision and outstanding AC performance, making it ideal for a wide variety of signal chain applications. It integrates a robust mux-compatible architecture and solves common system distortion and settling problems while providing the superior accuracy required in multiplexed multichannel precision signal chains. Whether designing medical, automotive, industrial, robotic, IoT, or other precision equipment, the ADA4510 can be an asset.
After completing his studies in electrical engineering, Jon Gabay has worked with defense, commercial, industrial, consumer, energy, and medical companies as a design engineer, firmware coder, system designer, research scientist, and product developer. As an alternative energy researcher and inventor, he has been involved with automation technology since he founded and ran Dedicated Devices Corp. up until 2004. Since then, he has been doing research and development, writing articles, and developing technologies for next-generation engineers and students.
Analog Devices has built one of the longest standing, highest growth companies within the technology sector utilizing cultural pillars such as innovation, performance, and excellence. Acknowledged industry-wide as the world leader in data conversion and signal conditioning technology, Analog Devices serves over 100,000 customers, representing virtually all types of electronic equipment. Celebrating over 50 years as a leading global manufacturer of high-performance integrated circuits used in analog and digital signal processing applications, Analog Devices is headquartered in Norwood, Massachusetts, with design and manufacturing facilities throughout the world. Analog Devices' is included in the S&P 500 Index.