The **FUD-155-R/Q** is a high-performance **Optical Receiver Module** typically used in fiber-optic communication systems, specifically for SDH (Synchronous Digital Hierarchy) and SONET networks. These modules are designed to convert optical signals into electrical signals at high speeds. --- ### 1. Key Electronic Specifications The module integrates several sophisticated electronic components to handle high-speed data integrity. | Parameter | Typical Specification | | :--- | :--- | | **Data Rate** | Up to 155 Mbps (STM-1/OC-3) | | **Photodetector Type** | InGaAs PIN Photodiode or APD | | **Supply Voltage** | +3.3V or +5.0V | | **Operating Wavelength** | 1100nm to 1650nm | | **Package Style** | 2x9 or 1x9 SIP (Single In-line Package) | | **Sensitivity** | Typically -34 dBm to -37 dBm | --- ### 2. Internal Electronic Architecture The "R/Q" designation often refers to specific variations in the output logic or internal amplification stages. The internal circuitry generally consists of three main stages: #### A. Trans-Impedance Amplifier (TIA) The photodiode converts light into a very weak current. The TIA is the first electronic stage that converts this current into a usable voltage while minimizing noise. #### B. Limiting Amplifier (Post-Amp) Since the input optical power can vary, the TIA output voltage varies. The Limiting Amplifier "levels" this signal to a constant amplitude, ensuring the downstream digital circuits receive a stable high/low signal. #### C. Signal Detect (SD) / Loss of Signal (LOS) This electronic sub-circuit monitors the input power level. If the optical signal falls below a certain threshold, the module triggers an SD/LOS pin to alert the system of a link failure. --- ### 3. Pin Configuration (Common 1x9/2x9) The electrical interface usually follows a standard industrial footprint: 1. **Vee (GND):** Ground connection. 2. **RD+ / RD-:** Differential Data Outputs (usually LVPECL or TTL logic). 3. **SD (Signal Detect):** High/Low status indicator. 4. **Vcc:** Power supply. --- ### 4. Applications * **Telecommunications:** Access networks and metro area networks. * **Industrial Control:** High-speed data links in EMI-sensitive environments. * **SDH/SONET:** Standardized 155Mbps fiber links.