APD evaluation board simplifies infrared system development

Phlux Technology is offering an evaluation board for its Aura family of Noiseless InGaAs avalanche photodiodes (APDs). The APDs are used as 1550nm infrared sensors and claim 12 times greater sensitivity than conventional devices in applications spanning laser rangefinders, optical networks, test equipment, and LiDAR.

The 70mm x 60mm board, which features a MAX40661 transimpedance amplifier, is designed to expedite design and development by simplifying the evaluation and measurement of the company's Aura line of APDs (200, 80, and 30µm devices). Customers can quickly set up measurements such as APD dark current, responsivity, Noise Equivalent Power (NEP), Input Referred Noise (IRN), and dynamic characteristics, including impulse response, rise and fall times, and output swing, to compare with existing designs. The board has a protected DC-coupled input and an AC-coupled differential or single-ended output via 50Ω SMA connectors. It requires a single, low-noise +3.3VDC power supply, and the recommended Vbias is preset to meet the necessary level of responsivity. It is recommended for use with an oscilloscope featuring a 250MHz bandwidth.

The evaluation board accepts hermetically sealed TO-46 or TO-56 packaged APDs or Ceramic PLCC6 SMD packaged devices with a quartz window. The company supports these packages, but the board also allows for performance comparison with other commercially available devices in similar formats.

In addition to the evaluation board using the MAX40661 COTS preamplifier, Phlux has developed an ultra-low noise preamplifier circuit from discrete components to enable best-in-class NEP performance of <30fW/√Hz for demanding rangefinder and LiDAR applications with up to 75MHz bandwidth using the Aura 200 µm APD. This design is well-suited to defence applications.

Phlux's Noiseless InGaAs APD technology adds an antimony (Sb) alloy to the InGasAs compound semiconductor structure. The resulting devices operate with an internal gain of up to 120 or more, allowing the detection of the weakest signals above the noise floor. They also exhibit greater temperature stability and faster large-signal recovery than traditional InGaAs infrared sensors.