R & D Of Ultra-low Power Configurable Baseband Filter For UHF RFID Receiver

With the development and progress of wireless communication technology, 900MHz Radio Frequency Identification (RFID) systems have been applied in different mobile communication terminals because of its optimal communication distance and fast date rate.Mobile terminal general use batteries as its power supply, so one of the most important performances in mobile terminal is Service life. However the limited battery power restricted the promotion of RFID systems applied in mobile terminal, In order to prolong working time of terminals, low power technologies must be used to reduce the power consumption of the chip.As one of the most important blocks, analog baseband filter consumes a large proportion of power consumption in the RFID receiver. It is worthwhile to research on low power design of baseband filter.It can reduce the power consumption of the whole receiver chip and promote the application of RFID in mobile terminal.This thesis presents a low power baseband filter solution based on novel ultra-low-power low-gain high-bandwidth opamps. Digital calibration is applied to DC offset.Main works of this thesis are as following:1. Active-RC filter is introduced in detail; analysis the impact of filter in the receiver system; Tow-Thomas structure has gradually become the mainstream because it is easy to achieve gain configured and cutoff frequency configured.2. Giving the analysis of the conventional high gain low bandwidth opamp and low gain wide bandwidth opamp effects on the closed loop. Analyzed the ultra-low power filter scheme used low gain wide bandwidth opamp, realized an ultra-low power consumption low gain wide bandwidth adaptive biasing push-pull buffer opamp.3. Using Tow-Thomas differential biquadratic structure designed a gain and cutoff frequency adjustable 4 order Bessel filter. The stability of the structure of biquadratic linearity and noise are derived. And impact caused from non-ideal opamp is also derived. It can be looked as a guidance in filter design flow.4. Digital assisted circuit is applied to DC offset. It saved area effectively, reduced the setting time, and reduced the power consumption of the whole filter, further improve the energy efficiency.