Research Of The Key Circuits For X/ku Band Transceiver Front-end

Microwave transceiver is an important part of the communication system, which is essential in communication, radar, electronic countermeasures, and various kind of electronic measurements, The merits of its performance will directly affect the quality of the signal. With the continuous development of electronic technology and the widespread application, the data volume of the communication has a sharp increase and the electromagnetic environment is increasingly complex. In order to meet various needs, the performance of the transceiver is demanded higher, such as the work frequency of the transceiver, bandwidth, dynamic range, volume and power consumption, etc.At first, the implementation methods of receiver and transmitter technology are briefly introduced, and at the same time the working principle and the possible problems of various structures are analyzed with some existing solutions. Through compare the superheterodyne structure, zero intermediate frequency structure, mirror frequency suppression structure and the digital structure, and combining with the actual engineering requirement, finally we determine to use the superheterodyne structure to implement the circuit of the transceiver system in the project, which has high selectivity, large dynamic range, high sensitivity, etc.In this paper, we design the wide-band receiver RF front-end circuit, which is used in the master station of a time difference of arrival(TDOA) location system, and the narrow band communications transmitter RF front-end working in the Ku-band. As the receiver operates at 5-11 GHz frequency and has 80 dB dynamic range, we need on the basis of reasonable dividing frequency to add automatic gain control(AGC) circuit to meet such a high requirement. After considering the cost and difficulty of circuit implementation, we finally design the AGC circuit in the form of feedback to realize the goal, which consists of different gain branch circuit structure selected by corresponding switch, with the detection circuit placed after the first frequency conversion. According to the specific frequency planning and appropriate gain distribution, we choose the applicable components to build the circuit and account index of each device to ensure the performance of the circuit satisfy the conditions. After that the work is the design of the printed circuit board, processing, as well as the actual circuit debugging. According to the actual test condition, we make necessary adjustment to the circuit and solve the problem in the process testing. By the final testing result, all the indicators meet the requirements. The Ku band transmitter works in 16.56 GHz, adopting two up-conversion superheterodyne structure. The main work contains scheme determination, index decomposition, basic device selection, printed circuit board design, and the assembly and the debugging process of the complete system. The actual testing results show that the transmitter performance meets the requirements of indicators, verifying the feasibility of the scheme.