Design Of UWB I/Q Demodulator Based On SiGe Technology

In recent years, wireless communication has been significant development, highperformance wireless communication products are widely used in both the military and civil fields. Extensive application in all fields requires the wireless communication receivers not only has the high sensitivity and linearity performance, but also the requirements for broadband improve day by day. Ultra-wideband(UWB) technology can provide high data rate, low power and low cost, short range wireless links, and it has great potential in short distance wireless communication field. Because of its low transmission power, it can coexist with the current wireless communication systems, which can ease the increasingly tense band resource requirements.In order to achieve the overall requirements for the broadband receiver system, the design of quadrature demodulator module is crucial. This paper introduces the design of ultra-wideband I/Q demodulator based on Si Ge technology. Firstly the paper introduces the characteristics of Si Ge process and the reasons for choosing this process, then analyzes Image rejection principle, details I/Q signal generator, gives the optimal method of signal amplitude and phase mismatch. A number of filter circuit in this design has realized the signal amplitude error is less than 0.1d B and the phase error is less than 0.7 deg. The mixer uses the classical gilbert unit circuit, the paper introduces the simulation method and optimization analysis of circuit parameters, including the conversion gain, noise figure, linearity, port isolation and impedance matching etc. In addition, the other unit circuit do a principle analysis and parameter simulation. Finally, the paper gives the layout design of the whole circuit, introduces the layout and wiring principle, the design idea of matching and symmetry.The wideband quadrature demodulator comprised of radio frequency voltage to current conversion circuit, the gilbert mixer circuit, the intermediate frequency amplifier, the bias current circuit and a high performance I/Q signal generator. The demodulator designs the enable port ENBL, to reduce the power consumption of the circuit. At the same time it can control the current pins respectively connect with the power supply or ground, the current of the demodulator can be adjusted, through which one can trade off the noise figure with the third order intermodulation intercept point according to the specified situation. Both the radio frequency port and the local oscillator port can operate in the frequency range of 0.4-4GHz. The conversion gain is 6.9d B, the single sideband noise figure(SSB) is 12 d B, the input third order intercept point is 23 d Bm, and the input 1 d B compression point is 4 d Bm at frequency of 0.9 GHz. Considering the compatibility to realize the monolithic integration of wideband receiver system, this design used the TSMC 0.35μm Si Ge Bi CMOS process.This design employed Spectre RF to accomplish the circuit simulation, used Virtuoso Layout Editor to finish the layout design and the comparison of pre-simulation and pro-simulation. At last, we give the test results for the design, the test results accord with design requirements.