Balanced detection cancels common‑mode laser relative intensity noise (RIN) and reduces the effective shot noise. The two GePDs are responsivity variance, and the TIA implements a differential input to fully exploit the common‑mode rejection ratio (CMRR > 60 dB).
There are several reasons why this particular code remains popular on forums and review sites: IPX-551
The measured of 115 dB·Hz²⁄³ is derived from two‑tone tests (Δf = 1 MHz) at an input power of –30 dBm. IPX-551