ADPD2210

The ADPD2210 is a low noise current amplifier designed to allow the use of smaller photodiodes by amplifying sensor signal currents by a factor of 24 while adding minimal noise. This amplification provides the system sensitivity of a large photodiode with the benefits of a smaller photodiode. A minimum linearity of 60 dB allows accurate extraction of very small time variant signals on top of large dc or low frequency offsets.

The ADPD2210 is optimized for pulse mode applications such as wrist worn heart rate monitoring (HRM) or finger worn pulse oximeter oxygen saturation (SpO2), where low power consumption and rejection of ambient light is critical. In photodiode applications, the ADPD2210 holds the sensor input to within ±5 mV (typical) of the reference terminal, providing near zero-bias voltage and allowing minimal dark current and shot noise limited performance.

The ADPD2210 is designed for applications where power conservation is critical. The ADPD2210 uses very little power, typically 140 μA with no input to 954 μA at full scale. A power-down pin places the ADPD2210 in standby when sensing is inactive. This mode adds critical time for battery-powered monitoring and can reduce battery costs in disposable applications.

Using the ADPD2210 to provide sensor site amplification reduces the effect of electromagnetic interference (EMI) in low level wired interfaces, providing improved signal-to-noise ratio (SNR) and rejection of interferer signals from nearby equipment. The combination of low power, high SNR, and EMI immunity enables low power system solutions not possible with traditional small current sensors, such as photodiodes plus transimpedance amplifiers (TIAs).

Applications:

• Photoplethysmography
• Photodiode measurements
• Small current pulsed amperometry
Any application requiring the ultralow noise amplification of small currents