A Frequency Adaptive Variable Capacitance Circuit

Abstract

The present invention is a frequency self-adaptive variable capacitance circuit, the input signal and the reference signal are connected to the phase detector and the frequency detector, and the latter compares the two signals and outputs the signal to control the on-off of the s0 and s1 switches of the charge pump module, so as to control the Capacitor matrix charging; the output of the charge pump module is connected to the comparator and the capacitor matrix respectively; the output terminal of the comparator is connected to the control terminal of the capacitor matrix and the shift counter; the output terminal of the shift counter is connected to the mixer; the output terminal of the capacitor matrix is ​​connected through a resistor The branch circuit voltage of the generated capacitor matrix is ​​connected to the voltage-controlled oscillator and the comparator, the output terminal of the voltage-controlled oscillator is connected to the mixer, and the reference signal output by the mixer is connected to the phase and frequency detector. The charge pump module includes 3 identical N-type MOS transistors and 2 identical P-type MOS transistors. The capacitance value of the capacitance matrix of the circuit can be adaptively changed according to the frequency of the input signal; the structure is simple, the cost is low, and it can be widely used in the design of multi-mode and multi-frequency filters.

Description

technical field [0001] The invention relates to an adaptive variable capacitance circuit structure technology, in particular to a frequency self-adaptive variable capacitance circuit. Background technique [0002] In the field of multi-mode and multi-frequency communication, the capacitance in the multi-mode and multi-frequency filter structure often needs to have the characteristic of adaptively changing with frequency. Since the MOS transistor capacitor array has partially replaced the varactor diode, and has been developed rapidly. Therefore, based on the capacitance matrix of MOS transistors, constructing a circuit whose capacitance value changes with frequency has broad application prospects. [0003] The application number published in 2007 is 200580033904.3 Chinese Invention Patent Application Publication Specification, which discloses a "capacitor array switched by MOS transistors", which is an integrated variable capacitor with low loss, and proposes a topology lay...

AI Technical Summary

Problems solved by technology

The MOS transistor capacitance matrix can realize the change of capacitance value, but this scheme realizes the adaptive change of capacitance by encoding the matrix circuit through digital circuit, the structure is complex, the cost is high, and it is difficult to be widely used

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