Variable bandwidth filter circuit for RFID read-write equipment |
Title： |
| Variable bandwidth filter circuit for RFID read-write equipment |
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Application Number： |
200710176858 |
Application Date： |
2007/11/06 |
Announcement Date： |
2008/03/19 |
Pub. Date： |
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Publication Number： |
101145207 |
Announcement Number： |
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Grant Date： |
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Granted Pub. Date： |
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ApplicationType： |
Invention |
State/Country： |
11[China|beijing] |
IPC： |
G06K 17/00 |
Applicant(s)： |
Tsinghua University |
Inventor(s)： |
Wang Ziqiang, Gao Tianbao, Zhang Chun, Wang Zhihua |
Key Words： |
Variable bandwidth, filter circuit, RFID, read-write equipment |
Abstract： |
The present invention discloses a variable bandwidth filter circuit, which belongs to the design field of analog integrated circuits, in particular relates to a coupling filter circuit in the radio frequency receiver of a RFID reader, and the present invention can be used in RFID readers. A high-pass filter consisting of a capacitor C and a resistor R is connected between a lower-frequency-conversion mixer which converts frequency directly and an intermediate-frequency amplifier; two ends of the resistor R are connected in parallel with controllable MOS-tube switches to form a high-speed filter circuit with variable bandwidth; used in the RFID reader integrated circuits, the high-pass filter circuit can flit out DC and low frequency components led by directly converting frequency; under specific input signal, the bandwidth of the high-pass filter circuit can change with the signal by connecting in parallel controllable switches on two ends of the resistance in the filter circuit to have quickly respond, thereby improving the speed of the reader. |
Claim： |
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Priority： |
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PCT： |
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