Fiber optic transceiver circuit diagram

Fiber optic transceiver circuit diagram

Fast Ethernet fiber optic transceivers not only greatly simplify the design of LAN, but also protect the investment in original copper cable LAN equipment, which has become an urgent need in the current market. Fiber optic transceivers allow designers to implement solutions for single-mode Gigabit Ethernet applications. This product consists of three parts: an optical transmitter, an optical receiver, and a box with built-in duplex SC connector. The transmitter contains a GE LX-spec 1300nm laser driven by a custom, silicon bipolar IC that converts differential PECL logic signals into laser diode analog drive signals. The receiver contains an InP-PID photodiode mounted with a custom silicon bipolar transconductance preamplifier IC and connected to the postamplifier and digitization circuitry. The signal detection circuit set in the post-amplifier provides a PECL logic high signal once a useful light signal is detected. This single-ended PECL output drives the standard PECL output through a load. The case is made of plastic with high strength, heat resistance, chemical corrosion resistance and good flame retardancy. The overall design has extremely high anti-interference and EMI performance.

Data line interconnection

The transceiver can directly interconnect with the +5V PECL signal. The transmitter input is DC coupled to the laser driver circuit, that is, there is no capacitive coupling termination resistor at the input. The laser drive circuit is also DC coupled, so that the output optical power of various duty cycle data patterns is relatively balanced. If the data has a long and continuous state time, the output optical power will gradually change its average value to its preset value.

In the receiver section, the preamplifier and postamplifier are AC-coupled, and the actual data output by the postamplifier is DC-coupled to their respective output pins. The signal detection output is a single-ended, +5V PECL signal that is also DC coupled to its output pin. Of course, the correct interconnect circuit should be set up between the transceiver and the supporting physical layer integrated circuit. Figure 1 is the recommended interface circuit.

Electronic components comply with various relevant regulations, making users safer and more reliable when using them. Electrostatic discharge (ESD). There are two important things to do to prevent ESD damage. First, corresponding precautions should be taken for ESD-sensitive devices, using grounded jumpers, and the operating desk and floor should be anti-static. Second, components in the chassis that are exposed to the outside, such as dual ISC connectors, should comply with mandatory system-level ESD testing standards. Electromagnetic interference (EMI). High-speed transceivers should meet anti-electromagnetic interference requirements, such as the FCC of the United States, CENELEC EN55022 (CISPR22) of Europe, and VCCI of Japan. Electronic components need to control electromagnetic radiation to reduce interference with nearby equipment. EMI performance also depends on the design of the chassis and the correct installation of the circuit boards within the chassis.