| With the progress in science and technology, wireless communication technology changes witheach passing day, WLAN（Wireless Local Area Networks) has been advanced quickly. Nowadays,IEEE（Institute of Electrical and Electronics Engineers) has proposed the draft of 802.11acstandard based on 802.11a/b/g and 802.11n. Based on this standard, a 5.8GHz power amplifierdesign is proposed.The transceiver is the essential part in Wi-Fi technology. As the wireless communicationchanges, the strict demand is focused on low cost and power consumption，high integrated level andcapacity. As an important module in transceiver，power amplifier is used to be designed usingcompound semiconductor. It brings the difficulties while being integrated with other devisedmodules using CMOS process on a single chip. This problem is avoided while using poweramplifier designed in CMOS process on the chip. But the low transconductance and breakdownvoltage of the active components in CMOS process with the low Q factor and high loss in thesubstrate become the problem in a reliable power amplifier design. It is challenging when designinga power amplifier with large output power，high linearity and efficiency. Power amplifier design is ahot topic these days in design community.It is introduced the basic power amplifier design information and process at home and abroadin the first of this paper. The difficulties and challenges in designing power amplifier using CMOSprocess is depicted and the solutions to these problems are summarized. Then the whole poweramplifier module is analysised in three parts as follow: input networks，output networks and activenetworks，which can help us understand the power amplifier clearly. And also，these analysis is usedto pave way to power amplifier design in the next.Through the analysis of the power amplifier stability and the methods to improving thestability, a novel method to estimate the RC value is presented in this paper, which facilitatescircuits design. It is verified in stability design of common source amplifier and cascode amplifier.The linearity of power amplifier is also studied in the text, and a new improving linearity method isproposed. On the base of IBM CMOS 90nm process，we design 3 single power amplifier to provethis method,and the 1dB output power is exceed 1.7 dBm than others that referred in preciousdesign.Based on CSMC .18um CMOS process, a 5.8GHz power amplifier is designed. And thispower amplifier is composed of 3 stages amplifier. And the common amplifier is adopted in powerstage, and thick MOS transistor that improves the output power in a higher operation voltage is used in this common amplifier. Self-biased cascode amplifier is used to drive stages in the poweramplifier, which do not only increase the gain and reverse isolation, but also alleviate the danger ofoxide breakdown and hot carrier effect. The 1dB output power of this power amplifier is 22.52dBm,power gain is 23.1dB and PAE is 40.8%.At the last of this paper, a power combination amplifier is designed based on the analysis ofrequirements and methods on combinational power amplifier. SMIC 65nm CMOS process is usedin this power amplifier and transformers design. The active units of this power amplifier usepseudo-differential structures which effectively suppress the packaging effects and bonding-wireeffects. The bonding-wire added at the source of MOS transistor reduces the power amplifier gainand bring oscillation. The loss which brought from signal flow in substrate and the effects to othermodule on a chip also can be decreased by using pseudo-differential amplifier. In this poweramplifier design, centre-tapped transformer is used to exclude the use of choke inductor, whichenhances the integrated degree. The 1dB output power of this power amplifier is 19.43dBm, powergain is 20.3dB and saturated output power is 20.88 dBm .In a word, it is studied on stability and linearity of power amplifier on the base of Wi-Fitechnology. A new method to to estimate the RC value in a stability design and another improvinglinearity method are proposed. The single-end power amplifier and power combinational amplifieralso are designed in this text. From the study and design of power amplifier using CMOS process, itis paved way to design power amplifier that can put into applying in radio-frequency integratedcircuits and products related radio-frequency integrated circuits. |
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