Radio frequency band-pass filter circuit

Abstract

The invention discloses a radio frequency band-pass filter circuit which comprises a first resonance module and a second resonance unit, wherein the first resonance module is used for receiving ratio frequency signals, suppressing ratio frequency signals with a first preset resonance frequency in the ratio frequency signals, carrying out frequency selection on ratio frequency signals with a second preset resonance frequency and suppressing other ratio frequency signals beyond the ratio frequency signals with the second preset resonance frequency; and the second resonance unit is used for receiving the ratio frequency signals output by the first resonance module and suppressing ratio frequency signals with a third preset resonance frequency in the radio frequency signals. The circuit has good filter effect and also can guarantee the receiving interference resistance and the receiving sensitivity of ratio receiving equipment.

Description

technical field [0001] The invention relates to filter technology, in particular to a radio frequency band-pass filter circuit. Background technique [0002] Receiving immunity and receiving sensitivity are very important for wireless receiving equipment such as receivers, and these requirements are directly related to the radio frequency bandpass filter of wireless receiving equipment. [0003] The existing radio frequency bandpass filter basically adopts the circuit structure of strong capacitive coupling or parallel connection of inductance and capacitance with fixed zero point coupling, as follows figure 1 In the shown RF bandpass filter circuit, the capacitance values ​​of the varactors D9014 and D9015 are tuned by the controller TUNE TV to obtain different resonant frequency points, thereby realizing the selectivity of different frequencies. [0004] However, in this RF bandpass filter circuit, because of the strong capacitive coupling form between stages, the bandwid...

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Problems solved by technology

[0004] However, in this RF bandpass filter circuit, because of the strong capacitive coupling form between stages, the bandwidth will become larger as the frequency rises, and this circuit has only one zero point, and the zero point is on the left side of the waveform, so it cannot Ensure that the spurious signals on the right side of the near end of the radio frequency signal are effectively suppressed, and the filtering effect is poor, resulting in poor reception immunity of the wireless receiving device; and if you want to suppress spurious signals, improve the receiving immunity of the wireless receiving device interference, it is necessary to reduce the bandwidth of the RF bandpass filter circuit, which will increase the loss of the filter circuit and reduce the receiving sensitivity of the wireless receiving device

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