Signal-processing and analog chips inside optical transceivers, including PAM4 and coherent DSPs, transimpedance amplifiers, and drivers. They sit between the optical engine and module assembly. Tight readings limit module shipments even when the optical engine is available.
A sustained tight read means the signal-chain electronics inside optical transceivers, not the optical engine, set how many modules can be built and shipped. Modules cannot be completed until DSP and analog chip supply is available, so transceiver output stays gated on those components rather than on optics or assembly. Relief arrives only as added chip supply qualifies and ramps, over quarters rather than a single order cycle.