AD620 Microvolt/Millivolt Voltage Amplifier Module

AD620 Microvolt/Millivolt Voltage Amplifier Module is a high-precision, low-cost instrumentation amplifier that lets you accurately measure and boost tiny voltage signals from sensors. Built around the renowned Analog Devices AD620 IC, this module provides exceptionally high common-mode rejection (CMRR) and low drift, which means it effectively filters out electrical noise while amplifying only the true signal. Engineers and researchers rely on this board to convert minute electrical changes from devices like strain gauges, thermocouples, and medical sensors into a usable voltage range for microcontrollers or data acquisition systems. A key advantage is its ease of use: you simply adjust an onboard precision potentiometer to set the gain from as low as 1.5 times up to an astonishing 1000 times, making it highly adaptable for various applications.

Key Features:

• High Precision and Low Noise: Integrates the AD620 instrumentation amplifier, known for its high accuracy and low input voltage noise.
• Adjustable Gain: A multi-turn precision potentiometer allows you to easily set the gain (amplification factor) continuously from 1.5x to 1000x.
• Wide Input Voltage Range: The module can handle signals as small as microvolts and millivolts, common in sensor applications.
• Excellent Common Mode Rejection Ratio (CMRR): Effectively rejects noise and interference common to both input lines, crucial for reliable sensor readings in noisy environments.
• Output Filtering: Includes a dedicated pin to output the amplified signal, often with basic filtering to further reduce high-frequency noise.
• Power Flexibility: Supports a wide input voltage range, and some versions offer dual-supply capability for truly bi-polar signal amplification.

Technical Specifications:

• Amplifier IC: AD620 (Instrumentation Amplifier)
• Input Voltage Range (V_in): Typically Microvolt to Millivolt level
• Output Voltage Range (V_out): Within the supply voltage range (usually VCC – 1.5V)
• Adjustable Gain: 1.5 to 1000 (Adjusted via Potentiometer)
• Input Supply Voltage: DC 5V to 30V (Single Supply)
• Bandwidth: Varies with gain; up to 120 kHz at G=100
• Offset Voltage Drift: Low, suitable for stable measurements.

Mechanical Specifications:

• Mounting: Two or four mounting holes for easy installation into enclosures.
• Component Access: Onboard multi-turn precision potentiometer for gain adjustment.
• Connectors: Screw terminals or standard pin headers for input and output.

Dimensions:

• Board Length: ~50 mm
• Board Width: ~40 mm
• Board Thickness: ~1.6 mm

Pinout and Wiring:

• VCC/GND: Power supply input terminals.
• V+ / V-: Differential signal input terminals (connect to the sensor output).
• V_out: The amplified output signal (connects to ADC pin of microcontroller).
• REF: Reference voltage pin (allows shifting the output baseline, typically connected to GND).
• Wiring Note: Connect the sensor’s positive and negative signal lines to V+ and V- respectively. For the best noise rejection, use shielded twisted-pair cables for the input lines.

Datasheet Reference:

• Download AD620 IC Datasheet

Commonly Used in:

• Biomedical Equipment: Amplifying low-level physiological signals like ECG (Electrocardiogram) and EEG (Electroencephalogram).
• Industrial Measurement: Interface with bridges (Wheatstone), load cells, and pressure sensors that produce small differential signals.
• High-Accuracy Data Logging: Providing the first amplification stage for precision sensor arrays in research or testing.

Applications:

• Strain Gauge Amplification: Accurately measure minute deformations using load cells and strain bridges.
• Thermocouple Signal Conditioning: Boost the very small voltage output of thermocouples for accurate temperature reading.
• Bridge Sensor Interface: Create a robust front-end for any sensor configured in a Wheatstone bridge arrangement.

Equivalent Models:

• INA122/INA125: Texas Instruments alternatives that perform similar low-power instrumentation amplification.
• AD623: A single-supply, rail-to-rail output instrumentation amplifier, sometimes preferred for simpler power requirements.

Package Includes:

• 1 x AD620 Microvolt/Millivolt Voltage Amplifier Module