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Design and Implementation of X Band CMOS Vector Modulator

Arjmandpour, Sina | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48856 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Medi, Ali; Kavehvash, Zahra
  7. Abstract:
  8. In this thesis, an X band vector modulator chip in CMOS .18 um technology is designed, implemented and measured. The receiver with two RF signal path includes differential amplifier, hybrid, attenuaters, variable gain amplifiers (VGA) and power combiner blocks respectively. Capability of gain and phase control is provided by 14 digital bit. 6 bits are used to control gain of each RF path, so that changing the phase and gain of the output signal in a trigonometric quarter shall be possible. The trigonometric quarter is selected by two single pole double throw switch. Cascode structure is utilized in amplifiers stages for its stability and isolation feature. Furthermore, in order to to enhance noise figure of system, in each amplifier, degeneration inductance is used in source of input stages. With this technique, reciever noise figure becomes 9 dB. Due to operational frequency of circuit and relative long wavelength, implemention of Distributed microwave circuits such as hybrid and combiner, occupy a large space in the chip. Therefore equivalent lumped model is being used in this receiver. Final circuit achieves 10.5dB gain and 3dBm P1dB referenced to input in the lowest attenuation at 9-9.6GHz bandwidth. Total power supply current sourced to the chip is 500mA so some layout techniques is used to improve chip reliability and life time
  9. Keywords:
  10. Variable Gain Amplifier ; Phased Array ; Complementary Metal Oxide Semiconductor Technology (CMOS) ; X Band

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