Signal conditioners filter, isolate, and amplify analog signals in consumer devices, measuring instruments, and industrial and automotive systems.
This article highlights key applications that rely on signal conditioners and reviews their most common functions. It also explores different types of signal conditioners: universal, multi-channel, splitters, and isolators.
From handheld devices to data acquisition systems
Analog sensors monitor a wide range of environmental inputs, from temperature, humidity, and air pressure to vibrations, audio, light intensity, and acceleration. They also measure electrophysical variables such as voltage, current, and field strength. Because raw signals are often weak, distorted, or noisy, they require extensive processing to ensure accuracy, reliability, and compatibility with digital systems.
Handheld devices like smartphones, digital multimeters (Figure 1), and portable environmental monitors implement various forms of signal conditioning before data is sent to analog-to-digital converters (ADCs). Typically integrated within microchips, electronic engineers optimize these signal conditioners for specific sensors and functions, such as microphones, cameras, and accelerometers.
Signal conditioning is particularly crucial in large-scale data acquisition (DAQ) systems, from manufacturing process controllers and industrial automation systems to mining infrastructure and offshore drilling equipment. These Industry 4.0 systems (Figure 2) typically comprise sensors, discrete signal conditioners, ADCs, and computers for signal logging and analysis.
Notably, industrial signal conditioners are built to withstand harsh environmental conditions, including extreme temperatures, vibrations, and electromagnetic interference (EMI). They also offer a higher degree of customization and functionality for specific applications, including precision and isolation, alongside more complex signal processing.
Exploring automotive signal conditioners
Signal conditioners are essential for vehicle sensors monitoring thermal conditions, engine performance, acceleration, steering, and braking. Additionally, they play a crucial role in many advanced driver-assistance system (ADAS) features, such as radar for collision detection, cameras for lane departure warnings, and ultrasonic sensors for parking assistance. Lastly, signal conditioners enable vehicles to track in-cabin and external environmental conditions accurately.
Like their industrial counterparts, automotive signal conditioners withstand moisture, broad temperature fluctuations, electrical surges, and vibrations. Due to space constraints, automotive signal conditioners, integrated into various vehicle control units (VCUs) and sensor components, are typically compact, though discrete units are also available. Manufacturers design them for safety and reliability, adhering to strict standards such as ISO 26262 to maintain signal integrity despite EMI, shock, and thermal stress.
Key functions and operations
Signal conditioners implement many different functions to prepare analog sensor signals for accurate processing by ADCs. These include:
- Amplification: increases signal magnitude to bolster measurement resolution and sensitivity. This is crucial for thermocouples and strain gauges, where weak signals are magnified to a more measurable level (e.g., converting a 0-10 mV signal to a 0-10 V signal).
- Attenuation: reduces signal magnitude to prevent ADC overload. Attenuation is particularly important for signals originating from high-output sensors, such as piezoelectric accelerometers, pressure transducers, and photodetectors.
- Isolation: protects sensitive equipment by breaking the galvanic path between input and output, preventing damage from unwanted signals and ground loops. Signals are typically transferred optically or magnetically, essential for maintaining floating connections in diverse ground plane scenarios, such as sensors mounted on engines, medical devices, or power distribution systems.
- Linearization: transforms non-linear input signals into linear outputs, ensuring high accuracy despite inherent non-linearity.
- Conversion: converts analog sensor signals into standard interface signals, efficiently maintaining measurement accuracy in DAQ systems before ADC conversion.
- Filtering: eliminates unwanted frequencies from signals, such as noise from AC power lines, using passive, active, or digital components. Digital filters, adjustable without physical modifications, maintain signal clarity and consistency by blocking or allowing specific frequency ranges.
- Excitation: provides the necessary excitation voltage or current for active sensors to operate, ensuring accuracy and stability for precise measurement.
- Impedance matching optimizes the connection between sensors and DAQ systems, minimizing signal reflections and losses. It helps maintain signal integrity in high-frequency measurements or long cable runs.
- Cold-junction compensation uses thermally sensitive devices, including thermistors or diodes, to simulate and correct thermocouples’ cold junctions, primarily in industrial systems.
The different types of signal conditioners
Although there are many different types of signal conditioners, they are typically grouped into four primary categories. For example, universal signal conditioners (Figure 3) are one of the most common choices for consumer and industrial applications. They support various sensors and functions, from current, voltage, and thermocouples to temperature detectors (TDs), potentiometers, and linear resistors. Notably, universal signal conditioners include customizable programmable modules to meet specific input/output requirements.
Multi-channel signal conditioners provide additional input/output options, facilitating more complex configurations. Because they process multiple signals simultaneously, they are ideal for applications that require concurrent monitoring and control of several sensor inputs. Meanwhile, isolated signal conditioners prevent ground loop currents and shield industrial and medical control systems from electrical noise and transient voltage spikes.
Lastly, signal conditioner splitters distribute a single input as two identical outputs across separate, isolated channels, effectively preventing ground loops and transient disruptions. Use cases are diverse, spanning distributed sensor signals and multiple monitoring systems to duplicated signals that ensure redundancy in critical applications and synchronous data logging across disparate systems.
Summary
Signal conditioners are key components in consumer devices and appliances, Industry 4.0 systems, and automotive VCUs. They implement a wide range of functions to prepare analog sensor signals for accurate processing by ADCs, from amplification, attenuation, and isolation to filtering, linearization, and impedance matching. Signal conditioners are typically grouped into four major categories: universal, multi-channel, splitters, and isolators.
References
Signal conditioning: Methods to Process Analog Signals to Digital, TT Electronics
The Importance of Signal Conditioning, Omega
Adapt and Protect Digital and Analog Process Signals, Phoenix Contact
Signal Conditioners: Helping to Provide Precise Measurements, HBK
What is Signal Conditioning or Signal Conditioner? DEWESoft
Types of Signal Conditioners, Omega
What is Signal Conditioning, Metromatics
Guide to Signal Conditioning, Fluke
