Single-ended input is a common method for analog signal measurement, with its core feature being using a common ground (GND) as the reference point and transmitting voltage signals through just a single signal wire. Below are its main characteristics and applicable scenarios:
The measured signal uses the system's GND (ground) as a reference, requiring only one signal wire (e.g., AIN+), with the other side connected to GND.
Example:
If the voltage measured between AIN+ and GND is 2.5V, then the actual signal value is 2.5V.
No differential signal pair (e.g., AIN+ and AIN-) is needed, reducing wiring complexity.
Suitable for low-channel-count, low-cost systems (e.g., simple sensor interfaces).
Since it relies on a common ground, ground noise (e.g., interference from motors or frequency converters) in long-distance transmission can directly affect signal accuracy.
Typical Issues:
Ground potential drift (Ground Shift) causing measurement errors.
High-frequency noise (e.g., 50Hz power interference) superimposed on the signal.
Typically used for low-voltage signals (e.g., 0-5V, 0-10V), unsuitable for weak signals (e.g., μV-level outputs from thermocouples).
High-precision applications require amplifiers or filter circuits.
| Feature | Single-Ended Input | Differential Input |
|---|---|---|
| Number of Wires | 1 (signal + common ground) | 2 (AIN+ and AIN-) |
| Noise Immunity | Weak (relies on common ground) | Strong (rejects common-mode noise) |
| Typical Use Case | Short-distance, low-noise environments | Long-distance, high-noise environments (industrial sites) |
| Cost | Low (saves wiring) | Higher (requires isolation/amplification circuits) |
On-Board Sensors
Temperature sensors (e.g., NTC voltage divider circuits), potentiometers, photoresistors, etc.
Low-Speed Data Acquisition
Battery voltage monitoring, button level detection, and other scenarios with low precision requirements.
Consumer Electronics
ADC interfaces in devices like Arduino and Raspberry Pi (mostly single-ended inputs).
Symptom: Inconsistent ground potentials between devices cause measurement errors.
Solution:
Use isolated amplifiers (e.g., ADuM3190) to break ground loops.
Reduce signal transmission distance or switch to differential input.
Symptom: μV/mV-level signals drowned in noise.
Solution:
Add low-noise amplifiers (e.g., LTC6910).
Use shielded cables with proper grounding.
Suitable Scenarios:
Large signal amplitudes (e.g., >100mV).
Short transmission distances (<1 meter).
Well-established common ground (no significant ground potential differences).
Unsuitable Scenarios:
Industrial environments (long-distance, high-noise).
High-frequency or precision measurements (e.g., medical EEG, strain gauges).
The advantages of single-ended input are simplicity and low cost, making it suitable for short-distance, low-noise applications.
Its disadvantages are poor noise immunity and reliance on a common ground. In complex environments, differential input or isolation solutions should be prioritized.
