Research On Filtering Passive Devices And RF Transceiver Front End With Tunable Frequency Band

With the development of wireless communication terminals towards high integration,miniaturization and multi-function,the era of Internet of things(IoT)is coming.The convenience of smart city is gradually benefiting everyone.The new trend of the development of wireless communication systems also puts forward new requirements in the research field of radio frequency(RF).Based on this research background,in this work,RF passive devices with integrated filtering function and RF transceiver front-end with tunable frequency band are selected as the research objects.The main research contents are described as follows:1.A planar microstrip dual-wideband bandpass filter with multiple transmission poles is proposed.The proposed dual-wideband bandpass filter has eight transmission poles and three transmission zeros.The fractional bandwidth of two passbands are 94.1%and 27.8%,respectively.Meanwhile,the return losses(RL)are greater than 14.5 dB and the group delays are lower than 1.6 ns in both passbands.2.A planar microstrip dual-band bandpass filter with multiple transmission zeros and controllable center frequency ratio(CFR)based on coupled transmission line is proposed.The proposed dual-band bandpass filter has nine transmission zeros and four transmission poles.Two prototypes with CFR of 1.96 and 2.38 are simulated,fabricated and measured,respectively.The return losses in passbands of the two prototypes are greater than 15 dB.The insertion losses in stopbands of the two prototypes are greater than 10 dB.3.A filtering integrated power divider with all port impedance matching is proposed.In the passband,the return loss at the input port is higher than 25 dB and the isolation between output ports is greater than 10 dB.In stopbands,the insertion losses are higher than 13 dB.4.A RF transceiver front end based on zero if architecture with tunable frequency band is proposed.In the proposed RF transceiver front end,the budget gain of the transmitter(Tx)chain can be adjusted discretely in the range of-35 dB to 28 dB.The budget gain of the receiver(Rx)chain can be adjusted discretely in the range of 28 dB to 78 dB.When transmitting 16-QAM signal with symbol rate of 15 MHz,the Error Vector Magnitude(EVM)of proposed Tx and Rx is less than 7.8%and 5.0%in 2.3 GHz to 3.5 GHz,respectively.