Broadband photodetectors play a significant role in quantum optics and quantum information processing including the detection of squeezed pulses, quantum state reconstruction, and continuous-variable quantum key distribution system. By the noise analysis model of the photodetector based on transimpedance amplifier circuit, the electronic noise and signal noise characteristics are theoretically analyzed. And based on the PSpice simulation model, the effects of themain parameters on the performance of the photodetector are analyzed in detail. The input voltage noise of the operational amplifier is the main noise source of electronic noise, and the current noise of the operational amplifier affects the magnitude ofthe low-frequency noise. The input parasite capacitances play a non-negligible influence on the noise power spectrum. With the increase of the input parasitic capacitance, the electronic noise increases and the signal-to-noise ratio decreases. Through the comparisons between the theoretical calculation and the simulation results, these two analysis methods are equivalent. A wideband photodetector is developed by using a low-noise operational amplifier of OPA847. The experimental noise power spectrum is in good agreement with the simulation results, and the -3 dB bandwidth of the photodetector is 110 MHz.