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Design and Implementation of Ku-Band Variable Gain Amplifier in 0.18μm CMOS Technology

Barzgari, Mohammad | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48652 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Medi, Ali
  7. Abstract:
  8. In this thesis, a Ku-band (16.3-17.3) Variable Gain Amplifier (VGA) for realizing a phase array T/R module is designed, implemented and measured in CMOS 0.18μm technology. In order to achieve a maximum gain of 15dB and NF of 4.3dB and with the idea of improving the 1-dB compression point, two gain-stages and a novel inter-stage is proposed according to pre-distortion method. Applying this linearizing technique, makes it possible to get output P-1dB higher than 18dBm. Current steering technique is used for gain control mechanism. Gain tunabality range of 31.5dB is needed and this forces 6-bit operation with 0.5dB gain-step for the VGA. Because of loading effect of higher bits on the lower bits, 16dB and 8dB bits are implemented with attenuator architecture. Other linearization ideas like Near-Threshold-Biasing of output transistors is also considered in order to reduce the dc current consumption. But, because of circuit sensitivity, it is not used in the final design of this project. The dc bias current of stages is tunable and its maximum is about 170mA. So, due to high current operation, the reliability of transistors is increased in the Layout. The final chip includes two RX and one TX path and the designed VGA is used in each of them besides the phase-shifter and LNA blocks. The RMS gain error of 64 states of the measured chip is better than 0.25dB over the desired band width
  9. Keywords:
  10. Variable Gain Amplifier ; Predistortion ; Complementary Metal Oxide Semiconductor Technology (CMOS) ; Current Steering Structure

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