An active rc complex bandpass filter

A complex band-pass and low-pass filter technology, which is applied in the field of satellite navigation, can solve the problems of complex band-pass filter passband ripple increase, large power consumption, phase lag, etc., and achieve image interference suppression, simple structure, The effect of guaranteed linearity

Active Publication Date: 2022-07-05
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the active RC complex bandpass filter, due to the limited gain-bandwidth product (GBW) of the op amp, additional phase lag will be generated when the low-pass filter is shifted to the spectrum, resulting in an increase in the passband ripple of the complex bandpass filter
On the other hand, increasing the gain-bandwidth product of the op amp will lead to greater power consumption. Therefore, the market needs a method that can eliminate additional phase lag and reduce passband ripple under the condition that the gain-bandwidth product of the op amp is limited. complex bandpass filter for

Method used

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  • An active rc complex bandpass filter
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  • An active rc complex bandpass filter

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] An active RC complex bandpass filter such as figure 1 As shown, it includes a first low-pass filter, a second low-pass filter, and a connecting unit. The connecting unit is coupled between the first low-pass filter and the second low-pass filter. The first low-pass filter and the second low-pass filter The second low-pass filter is a fifth-order Chebyshev low-pass filter. The connection unit includes 5 groups of connection modules, each group of connection modules includes 4 coupling modules, and each coupling module includes a coupling resistor and a compensation capacitor in parallel with the coupling resistor. .

[0037] The first low-pass filter, the second low-pass filter and the connection unit jointly complete the filtering of the input signal. The value of the coupling resistor can be from several K to several tens of K, and the compensation capacitor can be several tens to hundreds of f F. If the coupling resistor is too large, the coupling capacitor cannot be...

Embodiment 2

[0047] An active RC complex bandpass filter according to Embodiment 1, the difference is:

[0048] The calculation and reasoning process of the compensation capacitor is as follows:

[0049] (1) Calculate the gain-bandwidth product GBW of the op amp in the first low-pass filter or the second low-pass filter, and the calculation formula is shown in formula (I):

[0050] GBW=A 0 ω 0 (I)

[0051] In formula (I), A 0 is the DC gain of the op amp, ω 0 refers to the bandwidth of the op amp;

[0052] Due to the limited gain-bandwidth product of the op amp, using the single-pole model of the op amp, the transfer function H(s) of the integrator is:

[0053]

[0054] Under the condition that the gain-bandwidth product of the op amp is limited, the existence of sτ will cause additional phase lag;

[0055] (2) In the present invention, in order to reduce the influence of the limited gain bandwidth product of the (sτ) op amp, a compensation capacitor is connected in parallel wit...

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PUM

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Abstract

The present invention relates to an active RC complex band-pass filter, comprising a first low-pass filter, a second low-pass filter, and a connection unit, wherein the connection unit is coupled to the first low-pass filter and the Between the second low-pass filters, the connection unit includes a coupling resistor and a compensation capacitor connected in parallel with the coupling resistor. The invention reduces the extra phase lag when the spectrum of the low-pass filter is shifted, and reduces the dependence on the gain-bandwidth product of the operational amplifier.

Description

technical field [0001] The invention relates to an active RC complex band-pass filter, belonging to the field of communication and satellite navigation. Background technique [0002] The main task of the wireless receiver is to receive the signal superimposed on the high-frequency carrier locally and convert it into a relatively easy-to-handle mid-low frequency baseband signal. Generally speaking, wireless receivers can be divided into super-heterodyne structure, zero-IF structure, low-IF structure and so on. Compared with the other two structures, the low-IF structure has the advantages of simple structure, high integration, low power consumption, low DC offset and low flicker noise. In the low-IF receiver, in order to remove the interference of the image signal, a complex band-pass filter can be used. The complex band-pass filter is a one-way spectrum shift of the passband of the low-pass filter, and only a single-side passband filter is obtained. Interference suppressi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03H11/04H04B1/16
CPCH03H11/04H04B1/16
Inventor 王永李亚萍周冉冉孙娟娟王志南
Owner SHANDONG UNIV
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