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PD10TIA User Guide

Last updated: 2020-02-19 PDF version


PD10TIA-80-DC photodetector user interface
  1. Supply +VCC pin with a voltage between 5.5 V and 9 V. Supply -VCC pin with a voltage between -5.5 V and -9 V. The board is regulated to ±5 V internally. Using more than ±6 V supplies increases power consumption without any significant improvement in supply noise rejection.

  2. Feed the SMA input with a maximum of 50 µA. The linear output voltage range of the transimpedance amplifier is between -3.7 V and +3.7 V.

  3. The output is available on the SMA connector (50 Ω impedance).

Interfacing photodiodes to the PD10TIA

The PD10TIA is designed to be used with external photodiodes. Here is the recommended way to interface the photodiodes with the PD10TIA using a coaxial cable.

On the diagrams Cd and Ccoax represent the parasitic capacitance of the photodiode and the coaxial cable, respectively.

Single-ended detector

PD10TIA-80-DC Single-ended detector mounting

Balanced detector

PD10TIA-80-DC Balanced detector mounting

Coaxial cable length and input capacitance

The input capacitance is Cin = Cd + Ccoax for a single-ended detector and Cin = 2 Cd + Ccoax for a balanced one. The PD10TIA-80-DC is stable with input capacitances up to 2 nF.

For a typical 50 Ω coaxial cable, the capacitance per unit of length is 1 pF / cm. Note that no specific characteristic impedance is required for the input coaxial cable.

The input capacitance mostly influences the noise performance of the amplifier. For example, we built a balanced detector using a pair of photodiodes with 0.9 A / W sensitivity and Cd = 5 pF. We measured the noise equivalent power without and with a 2 meter-long coaxial cable (Ccoax = 1 pF / cm x 200 cm = 200 pF):

PD10TIA-80-DC Input noise versus coaxial cable length

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