SLLSEK1B July 2014 – March 2018 ONET2804T
The ONET2804T is designed to be used in conjunction with a 750 μm pitch photodiode array or individual photodiodes and assembled into a receiver optical sub-assembly (ROSA). The TIA will typically be mounted on a ceramic substrate with etched connections for VCC, RSSI and 100 Ω differential transmission lines for the output voltage. The photodiode converts the optical input signal into a current that is supplied to the TIA through wire bonds. The TIA then converts the input current into a voltage and further amplifies the signal. It is recommended to set the output amplitude to the 500 mVPP level by bonding AMPL (pad 6) to VCC.
The ROSA is typically mounted on a printed circuit board (PCB) with 100 Ω differential transmission lines and RF connectors such as GPPO or 2.4 mm SMA. When measuring the output from the ROSA mounted on the PCB, the frequency dependent loss of the transmission lines will impact the frequency response. The loss can be de-embedded from the measurement to determine the actual frequency response at the output of the ROSA. Figure 43 shows a typical frequency response without the loss de-embedded and Figure 44 shows a typical frequency response with the loss de-embedded.