Research On Concurrent Multi-band Optical Transceiver

Optical links for the transmission of analog signals have continued to expand thanks to its simplicity,low loss, large bandwidth, low cost, and immunity to electromagnetic interference from external RF sources. However, long-term coexistence of wireless communication systems, which has led to a number of standards and a variety of bands. Therefore, the number of optical transceiver modules increases in the base station, and its bulk gradually extend. The power consumption and operating costs gradually increased eventually. In order to solve the above problem, a variety of standards and multiple concurrent multi-band frequency optical transceiver module is required in the current market. This thesis focuses on the research on concurrent multiband optical transceiver.First, a detailed analysis of the optical transceiver module transmission principle and key part is presented. The main technical indicators for optical transceiver modules, including power budget, bandwidth budget, noise analysis, linearity and dynamic range are analyzed.Analysis of the technical difficulties in concurrent multi-band is completed. Multi-band and multi-stage matching circuits of LNA are designed & simulated. First, we utilizes microstrip transmission line in series and the parallel microstrip stubs to convert the source and load impedances to 50 ohms in each stage for dual-band LNA. Then the main performance index of the multistage LNA is introduced. Finally the fabrication of the dual band matching circuit is applied to the design of the three-level cascade LNA. Finally, the dual-band multistage LNA is realized by three-level cascade design. The results show that the noise figure is less than 1dB, the S11 & S22 are less than 20 dB, and the gain is more than 40 dB when the amplifier operating at dual frequencies of 2.69 GHz and 2.70 GHz, which indicates that the two bands is absolute matching simultaneously.In order to achieve the purpose of multi-band signal transmission, a large bandwidth of 0-6 GHz analog optical transceiver system is designed finally. In order to facilitate the measurement of the transmission system, we divide the transceiver block into two parts, namely, the alternating circuit(AC) and the direct current circuit(DC). The DC circuit is used to test the performance of the transmitter and receiver, and the AC circuit is used to complete the mutually conver between the optical signal and the electrical signal. According to the actual situation, we built the experimental platform. We perform the test for both transmitter & receiver, S-parameter and two tones. The result indicates that the proposed transceiver has more than 6 GHz of the 3-dB gainbandwidth with 22 dB link gain, 31 dB noise figure,-9dBm P1 dB, 10 dBm OPI3 and 102 dB SFDR, the input and output matching is realized simultaneously. The whole system has excellent performance to complete multi-band signal transmission.