| With the technical development of RFIC (Radio Frequency Integrated Circuits) and Internet industry, the expanding speed of portable and mobile product market has been skyrocketing these years. In most advanced areas such as United States, Europe and Japan, city wireless network coverage has reached a high density. Electrical (or optical) cable, handset and WLAN (Wi(?)(?)less Local Area Network) are the three most popular ways of Internet connection. Though electrical (or optical) cable possesses stable and high-speed transmission characteristic, but its laying process is complex with high cost. Traditional WAP handset network has a wide coverage, but its signal transmission is slow and unstable. As newly sprouted thing, 3G mobile network has been being popularized in China, but the network reconstruction project still needs time. WLAN can locally access Internet with high-speed, convenient construction, low cost and stable signal, which is very suitable to be a complement for 3G network. Many specialists believe that,3G and WLAN combination will tend the mainstream of future communication development, namely 4G network, which means 3G network will cover the most communication areas, and WLAN will provide the local wireless connection. Thus network can realize full-range coverage.The handset with Internet connection function requires stable signal and long life battery strictly. But the battery energy capacity technique seems to meet a bottleneck, so to reduce circuit power consumption turns to be an important way during portable product design. The stability of signal transmission requires LO (Local Oscillator) signal of the transmitter in equipment must have pure frequency spectrum and anti-jamming capability.Being a key module of transmitter in WLAN mobile product, the VCO (Voltage-Controlled Oscillator) designed in this paper is just based on the industrial background mentioned above. The chief design target is to achieve low power consumption under the low phase noise precondition. This design adopts TSMC 90nm 1P9M 1.2V RFCMOS low voltage to realize low consumption, but has to face some difficulties. Traditional RFIC VCO structure in low voltage technology will generate problems such as hard to oscillate, worse phase noise and more sensitive to environmental jamming. How to gain an optimum relationship between power consumption, phase noise, time of starting oscillation and tuning range is the main point focused in this design.Some solutions have been put forward to deal with the problems mentioned above, and analog digitization is the representation of them. Though it can solve many problems during RF analog IC design in deep submicron meter technology, but it still can't i(?)place all conventional analog circuit component or structure.In this paper, the circuit and layout of a fully in(?)egrated complementary cross-coupled LC (inductance-capacitance) tank VCO with differential outputs for 802.11b WLAN transceivers are presented in TSMC 90nm 1P9M 1.2V RFCMOS low supply voltage technology. This paper has also shown the research results of VCO structure, operation theory, phase noise and component selection. The multiple tests and comparisons on spiral inductor have established a solid foundation for final design accomplishment especially. The circuit was simulated with Mentor Graphics software, and simulation results showed that the VCO designed in this paper totally meet the requirement of 802.11b standard mobile product, and the power consumption is extremely low.As a beneficial attempt, traditional RFIC design with 90nm low supply voltage technology is presented in this paper. At the end part of this paper, some questions and problems unsolved during design are also mentioned which are for the future further research. |
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