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Frequency calibration circuit of active RC (Resistor-Capacitor) filter

A technology of frequency calibration and filter, which is applied in the field of frequency calibration circuit of active RC filter, can solve the problem of active RC filter cut-off frequency drift, etc., and achieve the effect of preventing the influence of the circuit

Active Publication Date: 2012-01-18
CHINA KEY SYST & INTEGRATED CIRCUIT
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  • Summary
  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

[0002] In the existing active RC filter, the cut-off frequency of the active RC filter will drift due to the change of the on-chip capacitance with the process, temperature, etc., so it is necessary to calibrate the cut-off frequency of the active RC filter. to get the desired cutoff frequency

Method used

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  • Frequency calibration circuit of active RC (Resistor-Capacitor) filter
  • Frequency calibration circuit of active RC (Resistor-Capacitor) filter
  • Frequency calibration circuit of active RC (Resistor-Capacitor) filter

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Embodiment Construction

[0015] Such as figure 1 Shown is a schematic structural diagram of the frequency calibration circuit of the active RC filter of the present invention. Its structure includes a capacitor array charging and discharging circuit module 1 of the analog part, a voltage window comparison circuit module 2 and a capacitor array control signal feedback circuit module 3 of the digital part.

[0016] The capacitor array charging and discharging circuit module 1 includes a capacitor array 11, a transmission gate 12, an NMOS switch tube M113, an NMOS switch tube M214, and a tail current source It15, wherein the positive terminal of the capacitor array 11 is connected to a power line, and has a capacitance control word S, S, S, S; the negative end of the tail current source It15 is grounded; the sources of the NMOS switch M113 and the NMOS switch M214 are connected, and connected to the positive end of the tail current source It15 The gate of the NMOS switch M113 is connected to the reverse...

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Abstract

The invention discloses a frequency calibration circuit of an active RC (Resistor-Capacitor) filter, comprising a capacitor array charging-discharging circuit module of an analog part, a voltage window comparison circuit module and a capacitor array control signal feedback circuit module of a digital part, wherein a capacitor array in the capacitor array charging-discharging circuit module completely copies a capacitor array in the active RC filter, a voltage obtained through the copying is compared with an expected voltage in the voltage window comparison circuit module, then a signal obtained through voltage comparison is output to the capacitor array control signal feedback circuit module and is processed by the capacitor array control signal feedback circuit module to form feedback with the analog part, so that a control signal of the capacitor array is obtained, and furthermore, the capacitance of the capacitor array in the active RC filter is adjusted to realize the adjustment for frequency response of a main circuit of the active RC filter. The invention has the advantage of overcoming the defect of frequency response of the active RC filter due to influences from a process, a power voltage, a temperature and the like.

Description

technical field [0001] The invention relates to a frequency calibration circuit, in particular to a frequency calibration circuit of an active RC filter. Background technique [0002] In the existing active RC filter, the cut-off frequency of the active RC filter will drift due to the change of the on-chip capacitance with the process, temperature, etc., so it is necessary to calibrate the cut-off frequency of the active RC filter. to get the desired cutoff frequency. Contents of the invention [0003] The purpose of the present invention is to realize a frequency automatic calibration circuit applicable to active RC filters. [0004] In order to realize the purpose of the invention of the present invention, realize by adopting following technical scheme: [0005] A frequency calibration circuit for an active RC filter, comprising a capacitor array charge and discharge circuit module of the analog part, a voltage window comparison circuit module and a capacitor array con...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03L1/00
Inventor 尹莉
Owner CHINA KEY SYST & INTEGRATED CIRCUIT
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