The Transactions of The Korean Institute of Electrical Engineers (전기학회논문지)

The Korean Institute of Electrical Engineers (대한전기학회)
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Filter Calibration using Self Oscillation of Biquad RC Filter

바이쿼드 RC 필터의 자가 발진을 이용한 필터 교정

  • 안덕기 (강원대 전기전자공학) ;
  • 황인철 (강원대 IT특성화학부 전기전자)
  • Received : 2010.02.19
  • Accepted : 2010.03.16
  • Published : 2010.05.01
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Abstract

This paper presents a digitally-controlled filter calibration technique for biquad RC filter using self oscillation. The biquad RC filter is converted to a fully-differential ring oscillator by changing its resistor connections, where the oscillation frequency reflects the cut-off frequency. The proposed calibration circuit measures the oscillation frequency by counting with a fixed higher-frequency clock and then tunes it to a desired frequency with a digital frequency-locked loop including a PI controller. Because the proposed circuit directly measures the cut-off frequency of the filter itself and calibrates it with the small area digital circuits, the area and the power consumption are much small compared with conventional works. When it is implemented in a 65nm CMOS process, the calibration circuit except the filter consumes the area of 80um X 50um and power consumption is 443uA at 1.2 V supply voltage.

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References

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