Research And Implementation Of An L-band High Dynamic Range Receiver Front-end

Global navigation satellite system is an important spatial information infrastructure, which involves many subject areas, and the application scopes are gradually extended to all aspects of the national economy. The navigation receiver RF front-end which works in the L band is one of the most important parts of the navigation satellite system. Its performance and integrated level will highly determine the operation conditions and the application areas of the navigation satellite system. The L band receiver front-end chips based on CMOS process have advantages of improving the receiver integration level and reducing system cost. But at the same time, due to the characteristics of the navigation receiver, RF front-end chips should ensure a high dynamic range to suppress the electromagnetic interference cuased by either human or natural. In order to meet this challenge, this paper studied and implemented a high dynamic range RF front-end of the L band receiver based on CMOS process.This paper started with some generalities about the research background, and then obtained the conclusion from analyzing the research progress, which is the difficulty of L band receiver front-end chips in this research has been changed from implementing the basic function to improving the key indicators of the key modules of the front-end based on CMOS technology, which includes a thorough study of the dynamic range. The research methods used in this paper combined top-down and bottom-up research process. The structure and indicators of the receiver were analyzed at the first step to determine the target of the system, follows the dynamic range performance and the corresponding design methods were included. Furthermore, the research extended to the specific design methods of active or passive devices in the front-end chips and the chips of key modules were designed and optimized the performance. After all of the chips had been fabricated and tested, they were integrated with the whole RF front-end, and achieved a high dynamic range. The key modules which were studied in detail include low noise amplifier, mixer and IF amplifier in this article.In the study of low noise amplifier, this paper first introduced the traditional method named derivative superposition which was used to improve the linearity of the low noise amplifier previously. Then the design method was optimized and the bias voltage of the MOSFETs was determined by the higher order derivative for better superposition of the third order derivative. The effective of the derivative superposition could be maintained in higher input power range with this method, and it did not affect other performances of the circuits. The result of this optimization was the RF front-end can work in normal operation withstanding a stronger external interference. The circuit and layout were designed in 90 nm and 180 nm CMOS process respectively.In the next chapter, the paper studied the mixer and the IF amplifier circuits. After classifying the mixer circuit by various methods, the structure of voltage mode driver passive mixer was selected. After thorough analysis, especially the working condition in different local oscillator waveforms on this type of mixer were given and more coincident with the actual circs, a high bias high duty ratio local oscillator waveform was innovatively chosen to optimize the linearity of the mixer circuit. In addition, the procedure of designing the IF amplifier circuit was also introduced in detail, and the stability of the operation amplifier in the IF amplifier was analyzed. The circuit and layout design were also completed in 180 nm CMOS process.In the last chapter, all of the chips designed in this paper were fabricated and tested. All of the test results were consistent with the results obtained in the analyses and simulations. The noise and linearity performances of the key components in the RF front-end were improved a lot and it was proved the effectiveness of the circuit and layout design as well as the optimization process. Finally, this paper implemented an integrated RF front-end chip according to the design method of each module circuit, it could also work perfect under strong interference signals leading to achieve a higher dynamic range.