The Design Of 2-40GHz Ultra-wideband Integrated Transmitting Front End

With the development of microwave communication systems,miniaturization,ultra-wideband,and highly reconfigurable microwave modules have gradually become the first choice for electronic warfare communication systems.The transmitter front-end is an important part of the communication system.Based on the hybrid microwave multi-layer board technology and MCM(multi-chip module)technology,and the MMIC(microwave monolithic integrated circuit)technology is used for tight interconnection to achieve an integrated low cost ultra-wideband transmitter front-end for 2-40 GHz.First of all,this paper describes the development of miniaturized ultra-wideband transceiver front-end,introduces two key technologies,microwave multi-layer circuit and MCM-L(Laminated multichip module),and the frequency conversion structure of common transmitter.According to the requirements of system indicators,the system solution is designed,including 2-40 GHz ultra-wideband frequency conversion scheme design,IF link design,RF link design and power drive link design,and the key indicators of the system are estimated by ADS.Secondly,this paper analyzes the active MMIC chip of the transmitter,analyzes and designs the key passive components of the system,including: miniaturized design of passive filters and design of an ultra-wideband transition structure based on multi-layer circuit.The ultra-wideband transition structure is loaded by coaxial shield holes and in the passband of DC-44 GHz,finally achieves high performance index of in-band return loss better than-20 dB and in-band insertion loss better than-0.2dB.For the IF filters,based on the slow wave effect and the HMSIW(Half-mode Substrate Integrated Waveguide)technology,the filter circuit area is reduced by nearly 50%,and the selectivity is high,and the suppression of the local frequency leakage signal is greater than 50 dB;For the 2-18 GHz band filters,the traditional interdigitated structure is miniaturized,and a three-dimensional model of the multi-layer vertical folding scheme is established.The circuit area is reduced by nearly 50% compared with the conventional structure,and the return loss is better than-10 dB.For the 18-40 GHz band filters,the Chebyshev filter is miniaturized,and the DGS technology and the multi-layer circuit technology are used.The circuit area is reduced by more than 50% compared with the conventional SIW structure,and the insertion loss is better than-2 dB,the return loss is less than-10dB;At the same time,the SIW bandpass filter based on DGS and SIR structure is proposed.It has high selectivity and far parasitic passband characteristics,achieving 18-22 GHz return loss better than-10 dB,and insertion loss better than-1.5dB,26-40 GHz stop band rejection of more than 50 dB.Finally,the 3D structure layout of the transmitter front-end is designed,and the miniaturization design of the planar circuit layout and the cavity structure design are designed.The integrated design of the 2-40 GHz ultra-wideband transmitter front-end is completed,and the overall size is 50mm×40mm×13mm.After processing and testing,the gain of the module is greater than 50 dB,the output power is greater than +25dBm,the suppression is greater than 50 dBc,the transmission power flatness is less than ±1dB,and the output power control range of 25 dB can be realized,which meet the system index requirements.