PDA-750 Photodiode Transimpedance Amplifier

• Eight Decade Dynamic Range
• Less Than 1 pA Noise
• Maximum Resolution 1 part in +/- 20 000
• Rechargeable Ni-mH Batteries for Low Noise
• Digital Input of A/W Value Yields Readout in Watts
• Computer Interface for Easy Control
• Background Cancellation of +/- 200 %
• Digitally Set Bias Source from -14.00V to +14.00V

The PDA-750 is a low noise, high gain, transimpedance amplifier designed to provide a direct digital readout of the current generated from a photodiode photomultiplier, or other similar current source. With full scale input ranges of ± 20 nA to ± 20 mA and a noise level of less than 1 pA, the PDA-750 offers superb dynamic range.

Digital entry of an Amps/Watt setting via the front panel controls permits the instrument to display current measurements in units of Watts. The A/W setting ranges from 1.000 to 0.100.

A variable bias supply is built into the instrument and may be switched into series with the device under test. It can supply digitally selectable voltages ranging from -14.00 to + 14.00 volts.

The Offset control permits the nulling of background signals as large as ± 200% of the range currently in use.

Rechargeable batteries isolate the unit from the mains and eliminate the effects of ground loops and/or power line noise that may be present during sensitive measurements. They will power the instrument for approximately 10 hours between charges. The unit may be operated normally while the batteries are charging.

Applications for the PDA-750 include: serving as a precision readout device for Unity Quantum Efficient detectors such as the QED-150 manufactured by UDT Instruments, characterization of detector dark current, a readout interface for spectrometers, spectral calibration of detectors, a high gain precision transimpedance amplifier and as a sensitive, high precision optical power meter.