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Design of Radio Frequency CMOS Power Amplifier for Cellular Telephony

Ahmadian, Ali | 2008

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49387 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Haj Sadeghi, Khosrow
  7. Abstract:
  8. A Radio Frequency Power Amplifier was designed for IS-95 standard in 0.18μm / 1.8V CMOS technology. In order to increase output voltage swing and protect gate oxide of devices, pseudo-differential cascode topology was exploited. Bondwire inductors with exact modeling were used to tune out parasitic capacitances. A low-pass, L match impedance transformation network, realized using bondwire inductors, was used at output of power amplifier. An impedance transformation network design process was developed which considers the quality factor of inductors, from the first step. Also having examined the nonlinearity phenomena in power amplifiers, a fast simulation or measurement method was proposed that gives an estimate of the best bias point that minimizes ACPR up to peak output power. The power amplifier reaches the power gain of 22.5dB in PCS band, 1.885 – 1.910GHz, and power-added-efficiency is 46.3% at peak output power while ACPR is below the corresponding limit all over the output power range. The maximum output power of IS-95 standard is 250mW (24dBm), but the amplifier can deliver 500mW to compensate power dissipation in the following circuits. Then, having surveyed the power amplifier enhancement techniques, the average efficiency of amplifier was increased using adaptive bias technique. To apply the technique, two sets of bias points were examined. The first set of bias point results in more increase in average efficiency but the other set holds the power gain more constant over the output power range. The average efficiency of power amplifier is 1.18% which increase by 2.5x and 1.8x, using the first and second sets of bias points, respectively
  9. Keywords:
  10. Radio Frequency Power Amplifier ; Nonlinearity ; Complementary Metal Oxide Semiconductor Technology (CMOS) ; IS-95 Standard ; Adaptive Bias

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