Photodiode Amplifier

As part of the BMBF project Optocubes, we developed a particularly compact, but nevertheless powerful photodiode amplifier. This can be configured individually for a wide range of photodiodes and measuring methods or measuring ranges.

The standard version has a sample rate of 500,000 per second with a digitization depth of 16 bits. In comparison, the »Improved Version« offers 1 megasample per second at 24 bits. The integration times are adjustable from 1 µs to 1 s.

The offset voltage can be numerically corrected via software. The offset current can be compensated analogously via software in 0.1 pA increments. The diode bias voltage is fixed at 50 mV and the diode can be switched off by software.

There are various measuring methods for use in different applications.

Transimpedance Amplifier / Mean vs. Integration Time

In this setting, a transimpedance amplifier is converted at 500 kHz and its values are numerically averaged during the integration time.

The possible gains here are 10³, 10⁴, 10⁵, 10⁶ and 10⁷ V/A.

Maximum diode currents to full scale
(rounded):

• 10³ V/A: 5 mA
• 10⁴ V/A: 500 µA
• 10⁵ V/A: 50 µA
• 10⁶ V/A: 5 µA
• 10⁷ V/A: 500 nA

Maximum measured value
(rounded):

• 10³ V/A: 5 mA
• 10⁴ V/A: 500 µA
• 10⁵ V/A: 50 µA
• 10⁶ V/A: 5 µA
• 10⁷ V/A: 500 nA

Transimpedance amplifier / numerically summed over integration time

This measurement method is a true analog integrator whose final value is converted after the integration time.

The possible gains here are 10⁹, 10¹⁰, 10¹¹, 10¹² and 10¹³ V/A*s.

Maximum diode currents to full scale
(rounded):

• 10⁷ V/C: 5 mA
• 10⁸ V/C: 500 µA
• 10⁹ V/C: 50 µA
• 10¹⁰ V/C: 5 µA
• 10¹¹ V/C: 500 nA

Maximum measured value
(rounded):

• 10⁷ V/C: 500 nC
• 10⁸ V/C: 50 nC
• 10⁹ V/C: 5 nC
• 10¹⁰ V/C: 500 pC
• 10¹¹ V/C: 50 pC

Analog integrator

This measurement method involves a transimpedance amplifier, converted at 500 kHz, whose values are summed numerically during the exposure time.

Amplifications: 10⁶, 10⁷, 10⁸, 10⁹ and 10¹⁰ V/C.

Maximum diode currents to full scale
(rounded):

• 10⁹ V/As: 5 mA
• 10¹⁰ V/As: 500 µA
• 10¹¹ V/As: 50 µA
• 10¹² V/As: 5 µA
• 10¹³ V/As: 500 nA

Maximum measured value
(rounded):

• 10⁹ V/As: 1.2 µC
• 10¹⁰ V/As: 120 nC
• 10¹¹ V/As: 12 nC
• 10¹² V/As: 1.2 pC
• 10¹³ V/As: 120 pC

Have we aroused your interest? Contact our team to find the best confoguration for you!