Biography
Enrollment Date: 2005
Graduation Date：2009
Degree：M.S.
Defense Date：2009.06.02
Advisors：Chun Zhang Ziqiang Wang
Department：Institute of Microelectronics，Tsinghua University
Title of Dissertation/Thesis：Intermediate Frequency Circuits in Radio Frequency Identification
Abstract:
A series of typical intermediate frequency circuit used in radio frequency identification system is studied in this thesis. The intermediate frequency circuits include an Auto Gain-Control circuit, a Programmable Gain Amplifier with DC Offset Cancellation, and a intermediate frequency Low-pass Filter with programmable bandwidth. Primarily, an auto gain-control loop is present in this paper. A Gilbert structure is adopted as the forward amplifier with variable gain; a passive peek detector and a DC amplifier is adopted to produce the gain-control voltage and complete this auto gain-control loop. Secondly, an open-loop Programmable Gain Amplifier with source degeneration structure and a closed-loop Programmable Gain Amplifier with MOS current division structure are introduced. This paper presents a novel DC offset cancellation method for Programmable Gain Amplifier for Radio Frequency Identification receiver. The open-loop PGA with source degeneration structure exhibits -10 dB~20 dB gain range per stage with 2 dB step and 0.3 dB gain error. The DC offset is observed as 2% and 39.4 nV/sqrt(Hz) input referred noise at 40 kHz is achieved at the same time by inserting a filter in the DCOC loop. Then a closed-loop PGA with MOS current division structure are introduced; a OTA with two DCOC loops is adopted in this closed PGA. With -0.5~0.5V DC offset input, the DC offset input is less than 20mV. This thesis also presents an improved low-pass filter with programmable bandwidth used in radio frequency identification system. With resistance array instead of MOSFET variable resistance, the distortion of the low-pass filter is decreased.