Analysis And Design Of Mixer And Filter In Front-End Of RF Transmitter

In recent years, radio frequency(RF) wireless communication field has experienced rapid development. At the same time, with the development of CMOS technology, RF integrated circuit being low cost, low power consumption, high integration and high reliability has become the future trend. In RF wireless transceiver system, mixer realizes the function of transformation between the signal frequencies. Filter is used to achieve the band selection and signal suppression. They are important and indispensable components in wireless transceiver system.The mixer and filter research status are discussed first, and then according to the specific performance indicators in the system, we analyze the whole circuit realization structure and the impact of sub-circuit on the overall circuit performance. Finally, based on TSMC 90 nm CMOS technology, we complete the circuit design, layout design, and simulation, at the same time, we finish the chip test of filter.Active filter is used Q-enhanced LC structure and notch to achieve image rejection capability. Measured gain of this filter is 16.32 dB at the center frequency with 18.53 MHz of-1 dB passband, 89.17 MHz/96.56 MHz of-20 dB stopband. Image rejection ratio is 40.97 dB with power consumption of 26.40 mW. The chip works well and the performance meets the design requirements.Upconversion mixer is used pseudo-difference Gilbert cell, matching with inductance load. The simulation results show that the circuit achieves 140 MHz to 1.2 GHz signal frequency conversion with gain of 0.11 dB, input 1 dB compression point-2.19 dBm, noise figure of 6.3 dB and 10.7 m W power consumption.The design of RF integrated filter and mixer is one of the RF system on chip research challenges. The filter and the mixer designed in this paper will have a good application prospect.