How should the optical module of the data center be designed?
2017-10-08
With the economic globalization and the continuous development of China's optical communications industry, the domestic optical module manufacturers R & D capabilities, improve the production process, combined with the cost advantages of products, domestic enterprises significantly enhanced competitiveness. Light Counting predicts that by 2019, data center optical module sales will exceed 50 million. Over the past five years, 10G SFP+  modules sold 40 million, half of which used to the data center, 40G optical module sales smaller, 2015 is expected to 2.5 million, the data center accounted for 75%. In 2014, the data center optical module market value of 1.6 billion US dollars, by 2021 is expected to reach 4.9 billion US dollars.
 
Optical module basic principles
The optical module is composed of optoelectronic devices, functional circuits and optical interfaces. The optoelectronic devices include two parts: transmit and receive. (LD) or a light emitting diode (LED) to emit a modulated light signal of a corresponding rate, which is internally provided with an optical power automatic control circuit so that the output of the semiconductor laser The optical signal power remains stable. Receiving part is: a certain bit rate of optical signal input module after the light detection diode into electrical signals. After the preamplifier output the corresponding bit rate of the electrical signal.
 
SFP / XFP optical transceiver MCU program
SFP optical module consists of three parts: the light-emitting part, the light-receiving part and the single-chip control unit. The light transmitting part is composed of a photodetector, a transimpedance amplifier and a main amplifier, and the function is to complete the optical / electrical signal conversion; the single-chip microcomputer control The unit is the core that implements the module diagnostic function. Optical module through the standard I2C bus interface, including SCL and SDA, to communicate with the outside world, you can complete the data transfer exchange.
 
Fiberland's EFM8LB1 family of microcontrollers is a new generation of high-performance, small package analog enhanced 8-bit MCU, the highest frequency up to 72MHz, integrated high-performance analog peripherals, including 14-bit ADC, 12-bit DAC, ± 3 ℃ temperature sensor As well as high-speed communication interface, for high performance requirements of the application provides a solution, very suitable for use in the program.

Block diagram of SFP / XFP optical transceivers
Figure 1: Block diagram of SFP / XFP optical transceivers
 
Fiberland Optical Module Features:
• High-speed, high-resolution ADCs
- Supports 10-bit, 12, 14-bit resolution
- up to 1Msps (12bit)
- Supports up to 20 channels
• On-chip high-speed, high-resolution DACs
- 4 DACs
- Supports 12-bit resolution
- Programmable output current
• 6-channel PCA (Programmable Counting Array)
- Supports 8-bit to 11-bit and 16-bit resolution PWM outputs
• Hardware serial interface
- SPI, UART, and IIC
• High-performance CPU architecture
- Maximum speed of 72MHZ support.
- 70% single cycle instruction
• 16 to 64 flash memory that can be selected
• On-chip integrated high-precision oscillations
• Minimum 3mm x 3mm QFN package

In summary, the Fiberland EFM8LB1 family of microcontrollers has better analog performance, higher cost performance, smaller package and lower power consumption, making it ideal for high performance applications such as optical modules.
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