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Programmable/adjustable active electric resistance-capacitance wave filter and method thereof

A resistance-capacitor, active technology, applied in the direction of frequency selection two-terminal-to-network, multi-terminal-to-network, etc., can solve problems such as reduced control efficiency, integrated circuit design problems, and increased number of components

Inactive Publication Date: 2009-02-11
IND TECH RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In this way, the number of components on the circuit will increase, the control efficiency will decrease, and it will also cause problems in the design of the integrated circuit.
In addition, the cutoff frequency of this filter can only be adjusted within a fixed range, so the application range is limited

Method used

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  • Programmable/adjustable active electric resistance-capacitance wave filter and method thereof
  • Programmable/adjustable active electric resistance-capacitance wave filter and method thereof
  • Programmable/adjustable active electric resistance-capacitance wave filter and method thereof

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Embodiment Construction

[0080] The following description of the circuit of the present invention does not include the complete circuit structure of the active filter. The prior art used in the present invention is only cited here in an emphatic manner to help explain the present invention. Moreover, the drawings in the description are not drawn to scale, and their function is only to show the structural features of the present invention.

[0081] image 3 Shown is an improved active filter circuit of the present invention, which utilizes a differential amplifier D with double-ended input and double-ended output Amp , respectively with four controllable shunt devices 302, 304, 306, 308 (for example: resistance ladder circuit; Resistor Ladder; RL) and two identical capacitive elements C f The controllable shunt devices 302, 304, 306 and 308 all use the same switching element, and the voltage signal input from the filter input terminal can be converted into a current signal through the equivalent resi...

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PUM

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Abstract

The programmable and adjustable active low-pass filter has basic unit structure of resistor, capacitor and controllable current divider and is used for analog circuit. The controllable current divider is realized with resistor stairs comprising resistors. The filter has cut-off frequency determined by the time constant of the filter circuit, and the time constant is determined with the equivalent resistance and equivalent capacitance of the filter circuit, so that when the cut-off frequency produces some deviation during production process or use process, the filter may have its controllable current divider trimmed to regulate the equivalent resistance so as to maintain the constant cut-off frequency of the filter. The present invention provides also great cut-off frequency regulating method to shift the cut-off frequency to required value and to make the identical filter circuit applicable in different uses.

Description

technical field [0001] The invention relates to an analog filter circuit, in particular to fine-tuning and changing the cut-off frequency and gain of the active filter. Background technique [0002] A filter is a common and important unit in a signal processing system. Its function is to eliminate unwanted frequency band signals to retain or amplify required frequency band signals. In the advanced integrated circuit manufacturing process, it is a common trend to integrate the filter into the chip, especially in the communication market. With the continuous evolution and progress of the communication system, the signal processing circuit not only requires high-standard performance on the one hand, but also on the other hand. , it is often required to be able to switch and process signals of two systems in the same circuit at the same time; for example, the second / third generation (2nd / 3rd Generation) mobile phones in wireless communication, high-speed data / asymmetrical digita...

Claims

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Application Information

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IPC IPC(8): H03H11/04
Inventor 楼志宏陈弘易
Owner IND TECH RES INST
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