Design of Low Noise and High Gain Broadband Photodetector

The existing photodetectors at home and abroad are generally lack adjustable gain and bandwidth, which makes it difficult to optimize various parameters. A low noise differential photodetector is designed. Its main gain is adjustable in the range of 10k-l0M, bandwidth is adjustable in the range of DC-3Mhz, and compensation amplification gain is adjustable in the range of 1-10. The equivalent noise model of PIN (positive-intrinsic-negative) photodiode and its amplifier circuit is analyzed. The optimal signal-to-noise ratio is 47dB and the minimum resolvable optical power is 1nW. The output voltage amplitude is linear with the input light intensity. When the signal frequency is within 3MHz, the signal can be detected without distortion. While meeting the performance requirements, the adjustable parameters are easy to explore the influence of gain, bandwidth and other factors on the experimental results, which is flexible and easy to be applied and promoted in precision spectroscopy and quantum optics experiments.