| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 94 === In a modern wireless communication system, the system power consumption is an important issue, and the power amplifier (PA) is a very power-hungry device in the transmitter. In the early communication standard, envelope of the transmitting signal is constant and we can use non-linear but high efficiency PA in the transmitter. However, after the GSM/EDGE and WCDMA standard, the envelope of signal is not constant. It means that we need a linear PA, but there is a trade off between linearity and efficiency. There are many linearity techniques proposed to improve the linearity and efficiency of PA. LINC can make the transmitter use non-linearly but high efficiency PA to linearly amplify the signal and then improve the linearity and efficiency of the transmitter.
However, the LINC transmitter has some particular problems. After LINC transform, the bandwidth of the signal will be extended largely. The wide band signal is a big challenge to the phase modulator. The gain/phase mismatch between two loops will distort the signal and the distorted signal can’t meet the spec.
We modify the architecture of all-digital phase modulation transmitter proposed by TI, and make it be able to transmit the wide band WCDMA LINC signal. We use simulation to verify it meets the transmitter specification of WCDMA. After surveying some gain/phase mismatch solutions, we propose a new architecture which can use lower hardware cost but reduce the gain/phase mismatch efficiently.
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