1x9 Optical module knowledge and single-chip solutions.sfp transceivers module Factory

1x9 packaged Optical module products were first produced in 1999. They belong to fixed Optical module products. They are usually directly solidified (welded) on the circuit board of communication equipment and used as fixed Optical module. Sometimes referred to as 9-pin or 9PIN Optical module.

Why is it called that? This is because this fiber optic module has nine PIN angles, which is the most common packaging form of early optical modules and a type with high market demand. Mainly used in fiber optic transceivers, PDH optical terminals, fiber optic switches, single mode to multi mode converters, and some industrial control fields. In brief, 1x9 Optical module is a communication device with optical wave as carrier and optical fiber as transmission medium. It uses a light source to convert electrical signals into optical signals, which are input into optical fibers for transmission. It uses a photodetector to recover the optical signal in the fiber into an electrical signal, which is amplified, reshaped, regenerated, and restored to the original electrical signal.

General solution

The 1x9 packaged optical transceiver integrated module consists of optoelectronic devices, functional circuits, and optical interfaces, including transmission and reception parts. The general solution is as follows:

Transmission part: used to drive a semiconductor laser (LD) or light emitting diode (LED) to emit a modulated optical signal at a corresponding rate after processing a certain bit rate input electrical signal on the internal driving chip. It is necessary to use an independent driver chip (LDD) and a laser to jointly achieve the function of the emission part, and also to be equipped with a luminous detection circuit, optical power control circuit, temperature compensation circuit, etc. Some models of chips also integrate these functions. The backlight diode is used to convert the light output of the laser diode into corresponding photocurrent, and control the bias current of the laser diode LD through the APC loop feedback to maintain a constant light output power. The constant power value is set by the external resistor rapcset, while the time constant of the APC circuit is determined by the external capacitor CAPC.

Receiving part: After inputting an optical signal with a certain bit rate into the module, it is converted into an electrical signal through an optical detection diode. And after passing through the limiting amplifier (LA), the corresponding code rate electrical signal is output. At the same time, when the input optical power is less than a certain value, an alarm signal will be output. Independent limiting amplifiers (LA) and integrated TIA detectors should be used to jointly achieve the function of the receiving part, and equipped with light detection circuits, alarm output circuits, temperature compensation circuits, etc. Some models of chips also integrate these functions.

Single chip solution

The purpose of a single chip solution is to use a single chip to integrate all functional circuits except for photoelectric conversion, thereby reducing costs, simplifying layout, and increasing stability.

Transmission part: configured to input electrical signals with specific bit rates by driving semiconductor lasers (LD) or light-emitting diodes (LEDs) and emit modulated optical signals at corresponding rates. The chip integrates temperature detection function, while detecting the backlight circuit of the laser backlight diode, and automatically performs power compensation and temperature compensation.

Receiving part: After inputting an optical signal with a certain bit rate into the module, it is converted into an electrical signal through an optical detection diode. After passing through the internal limiting amplifier and differential amplifier of the chip, the corresponding code rate electrical signal is output. The chip integrates temperature detection function, while detecting the amplitude of electrical signals, automatically performing amplitude compensation and temperature compensation. When the input optical power is less than a certain value, an alarm signal is output.