The home light cat has both an ONU optical module and wifi. The wifi frequency band includes 5GHz, which can cause interference with the ONU detector due to the high-frequency electromagnetic waves. The ONU receiver's bit rate is 10Gbps, and its working bandwidth is 7-8GHz, which is close to the working frequency of wifi and can cause interference. The power of wifi is much stronger. However the current of the optical signal detected by our detector is very weak, which creates unilateral interference of wifi with the ONU detector, resulting in significant noise. The ONU BOSA, which contains the detector chip that is easily interfered with, can be shielded externally or have filter circuits installed. To deal with the power ripple, I connect a quenching resistor in series and add filter capacitors to the two groups of power supplies. Previously, only two capacitors were used, and the TO can was already crowded with the detector and the TIA.
With the added quenching resistor, packaged into TO can, the receiver's optical power range can expand, and the saturation and sensitivity of the two points can be taken into account. This can even improve the damage threshold for APD.
Series quenched resistors may lead to reliability risks for APDs. Reliability risks caused by surface diffusion carriers of mesa structures due to series APDs. To filter out the wifi, a filter network can be added, such as a common capacitor to GND filter. There already has filter in APD power supply side, and there is no need to add another. It can be combined with the design of the TIA chip to avoid introducing too many chips in a small TO cavity. However, the additional capacitor that is not connected to GND needs to be isolated because there are electrodes on the bottom of the capacitor, and the TO header itself is GND.
The internal structure of the wire includes 5 pin pins, 4 signal lines, and a base directly welded to GND.
The first layer has two capacitors, an isolation pad, and a TIA.
The second layer includes a brown quenching resistor and a wifi filter capacitor.
The detector is placed on top of the capacitor, with the red side on the photosensitive side of the detector.
When irradiating the vertical detector, the P electrode must be a gold wire, but some N electrodes can use gold wire electrical signal interconnection. However, N-type InP itself is the substrate and can be directly plated on the bottom of the detector to form a bottom N large electrode. This can achieve electrical interconnection through conductive silver glue, and the surface of the N electrode suspension can also be used.
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