Low Cost, High Voltage, Programmable Gain Instrumentation Amplifier Using the AD5292 Digital Potentiometer and the AD8221 In-Amp (CN0114)
The circuit shown in Figure 1 provides a low cost, high voltage, programmable gain instrumentation amplifier using the AD5292 digital potentiometer and the AD8221 instrumentation amplifier.
Figure 1. Programmable Gain Instrumentation Amplifier (Simplified Schematic: Decoupling and All Connections Not Shown)
The circuit offers 1,024 different gain settings, controllable through an SPI digital interface. The ±1% resistor tolerance performance of the AD5292 provides low gain error over the full resistor range, as shown in Figure 2.
Figure 2. Gain Error vs. Code
The circuit provides a high performance instrumentation amplifier that delivers the industry’s highest CMRR over frequency in its class and dynamic programmable gain for both single supply operation at +30 V and dual supply operation at ±15 V. In addition, the AD5292 has an internal 20-times programmable memory that allows the user to customize the instrumentation amplifier gain at power-up.
The circuit provides accurate, low noise, high gain and is well suited for signal instrumentation conditioning, precision data acquisition, biomedical analysis, and aerospace instrumentation.
Схемы и диаграммы
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