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Offset voltage for an charge amplifier

Category: Hardware
Product Number: AD7091R

Hello,

Regarding the Two-Chip Data Acquisition System for Piezoelectric Sensors CN0350, I am wondering why not simply use a voltage divider to generate the offset voltage HREF? What would be the disadvantages of leaving out the op amps U1B and U1C and just using the resistors R1 and R2? A more detailed description of the working principle would be helpful.

Thanks for your answer!

Greetings,

Thomas

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  • Hi,  .

    I agree with  's insights. One thing also to take note of is HREF comes from VREF. Thus, you need to isolate this section to noise. HREF is for signal conditioning of the AC signal. While VREF is the point of reference during the ACQ and CNV phase in the ADC. Charge redistribution on the binary weighted capacitors in the ADC causes current to be drawn from or sunk by the reference. With all these details, you can perceive that U1B and U1C is important for a more stable and optimize system.

    Regards,
    Jo