Research of Mixer for 5G Communications in 40-nm CMOS and High Image Rejection Ratio Modulators with Tunable Mechanism for Satellite Communications
Date Issued
2016
Date
2016
Author(s)
Lin, Sheng-Wei
Abstract
The thesis presents two design parts. In the first part, the down-conversion mixer is designed in 40-nm CMOS process. The frequency is at 38 GHz which is potential for 5G communication in the future. In the second part, the modulators are designed for satellite communications with active divider in 180-nm CMOS process at downlink frequencies from 17.5 to 21 GHz and uplink frequencies from 27.5 to 31 GHz. Currently, high data rate and high spectral efficiency is the main trend for wireless communication. The cost of using higher order QAM to improve spectral efficiency is that the system requires a higher signal to noise ratio (SNR) to achieve the same BER performance. Meanwhile, the demand of broad bandwidth to deliver multi-gigabit data transmission is significantly increased. There are many research papers reported about multi-gigabit data rates through multi-gigahertz channel. For high date rate, wide bandwidth is also needed. In order to achieve the goal, IQ match is the most important to deliver the high quality of high image rejection ratio (IRR) signal. First of all, there are various types of down-mixers with different driven techniques. In this design, the Source-Driven technique in 40-nm CMOS process is chosen. In addition, a buffer is designed for pushing mixer core behind the output stage of doubler. The variable gain amplifier (VGA) with the structure of current steering is added at the IF port. The proposed down-conversion mixer with IF VGA provides 2~8 dB conversion gain with acceptable tuning linearity from RF frequency of 32-40 GHz and LO frequency of 18-22 GHz. It also provides OP1dB of –5.12 dBm output power at RF frequency of 38GHz and IF frequency of 3.6 GHz under 9 dBm LO pumping power. Two 18-50 GHz IQ modulators with tunable mechanism in 180-nm CMOS process are additionally proposed. To achieve high image rejection ratio (IRR), two different active tuning circuits are proposed in this thesis, which is different from the previous passive only tuning mechanism. The measurement results of modulator1 show the average conversion gain -17±2 dB from 15 GHz to 50 GHz and especially in -7±2 dB from 17 GHz to 25 GHz. The output power of OP1dB is -8.16 dBm at 21 GHz and -9.03 dBm at 23 GHz. The measured image rejection from 15 GHz to 50 GHz is -30 dBc at 23GHz. Especially, Modulator2 provides better performances, measured conversion gain -17±2 dB from 15 GHz to 50 GHz and especially in -7±2 dB from 17 GHz to 25 GHz. The output power of OP1dB is -6.51 dBm at 21 GHz. The measured image rejection from 15 GHz to 50 GHz is -42 dBc at 29 GHz.
Subjects
sub-harmonic mixer
satellite communications
image rejection ratio (IRR)
tunable
Type
thesis
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