Intermediate frequency filter circuit for out-of-band reflection cancellation

专利摘要:
The present invention relates to an out-of-band reflection cancellation intermediate frequency filter circuit, in which a capacitor (C1) and a coil (L1) connected in series to a node A at an input terminal, and a capacitor (C2) and a coil connected in series at an output terminal to the node A ( L2), a band pass filter part including a capacitor C3 and a coil L3 connected in parallel with the contacts at the node A; Capacitor C4 and coil L4 connected in parallel to Node B at the input terminal, Capacitor C6 and coil L6 connected in parallel to the output terminal at Node B and capacitor C5 connected in series at the node B as contacts. It is composed of a band rejection filter composed of and coil (L5) to improve the performance of the WLAN receiver by removing the reflection components generated out of band in the intermediate frequency filter used after down conversion in the WLAN receiver.
公开号:KR19980061560A
申请号:KR1019960080931
申请日:1996-12-31
公开日:1998-10-07
发明作者:김영현；양철모
申请人:이우복；사단법인 고등기술연구원연구조합；
IPC主号:

专利说明:

Intermediate frequency filter circuit for out-of-band reflection cancellation
1 is a view showing a conventional intermediate frequency filter circuit
2 is a circuit diagram according to the present invention
3 is a diagram showing signal characteristics according to the present invention.
Explanation of symbols on the main parts of the drawings
1: Band pass filter part 2: Band rejection filter part
The present invention relates to an intermediate frequency filter circuit for reflection elimination of a band, and more particularly, to an intermediate frequency filter circuit for eliminating out-of-band reflections in an intermediate frequency filter used after down-conversion in a wireless LAN receiver. It is about.
FIG. 1 is a diagram illustrating a conventional intermediate frequency filter circuit, in which a signal generated at a radio frequency and a signal generated at a local oscillator are combined at a mixer and output at an intermediate frequency through a band pass filter.
In case of the conventional receiving module, out-of-band components are totally reflected at the front of the filter among many frequency components introduced into the band pass filter for the intermediate frequency, and fed back to the mixer and the local oscillator to produce more harmonic components. It is difficult to produce a mixer or a stable local oscillator with high separation and generating performance degradation and weakening characteristics of the RF circuit receiving circuit for the wireless LAN.
An object of the present invention is to improve the performance of a wireless LAN receiver by inserting a band rejection filter between an input terminal and an output terminal to solve the above problems.
In order to achieve the above object, the present invention provides a capacitor C1 and a coil L1 connected in series with a node A at an input terminal, a capacitor C2 and a coil L2 connected in series with an output terminal at a node A, at the node A. A band pass filter unit including a capacitor C3 and a coil L3 connected in parallel with a contact; Capacitor C4 and coil L4 connected in parallel to Node B at the input terminal, Capacitor C6 and coil L6 connected in parallel to the output terminal at Node B and capacitor C5 connected in series at the node B as contacts. And a band rejection filter composed of a coil L5 to suppress harmonic components generated by total reflection of out-of-band components.
Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.
2 is a circuit diagram according to the present invention, which is composed of a band pass filter part 1 between an input end and an output end, and a band rejection filter part 2 between an input end and a band pass filter part. 1) is the capacitor C1 and coil L1 connected in series at node A at the input terminal, the capacitor C2 and coil L2 connected in series at the output terminal at node A, and the capacitor C3 connected in parallel to the contacts at node A. ) And coil L3, capacitor C1 is 16PF, coil L1 is 57nH, capacitor C2 is 218PF, coil L2 is 40nH, capacitor C3 is 33PF, coil L3 Is 259 nH. Next, the band rejection filter unit 2 has a capacitor C4 and a coil L4 connected in parallel to the node B at the input terminal, and a capacitor C6 and coil L6 connected in parallel to the output terminal at the node B, at the node B. Capacitor C5 and coil L5 connected in series with contacts, capacitor C4 is 96PF, coil L4 is 91nH, capacitor C5 is 36PF, coil L5 is 240nH, capacitor C6 Is 200 PF and the coil L6 is 43 nH. In this case, out-of-band components generate total reflection and pass in-band components among the frequency components generated after down-conversion (harmonic components including 55 MHz and 2.4 GHz). Intermediate Frequency (IF) used in the reception of WLAN is 55MHz and the band is 22MHz. Therefore, the passband is 44MHz-66MHz, and the frequency components are totally reflected back to the input. At this time, a band rejection filter is inserted between the input terminal and the band pass filter unit so that out-of-band components are matched to 50Ω without being fed back to the input terminal.
3 is a view showing the signal characteristics according to the present invention, which shows that the desired bandpass characteristics and the out-of-band total reflection components of the input stage are removed by combining the characteristics of the band pass filter and the characteristics of the band rejection filter.
The present invention can improve the performance of the WLAN receiver by removing reflection components generated out of band in the intermediate frequency filter used after down conversion in the WLAN receiver.

权利要求:
Claims (5)
[1" claim-type="Currently amended] A band pass filter unit between the input terminal and the output terminal;
And a band rejection filter between the input terminal and the grounded resistor to suppress harmonic components caused by total reflection of the out-of-band frequency.
[2" claim-type="Currently amended] The method of claim 1,
The band pass filter unit has a capacitor (C1) and a coil (L1) connected in series with the node A at the input terminal,
A capacitor (C2) and a coil (L2) connected in series with the output terminal at the node A,
And a capacitor (C3) and a coil (L3) connected in parallel to the contacts at the node A.
[3" claim-type="Currently amended] The method of claim 1,
The band rejection filter has a capacitor (C4) and a coil (L4) connected in parallel to the node B at the input terminal,
A capacitor (C6) and a coil (L6) connected in parallel to the output terminal of the node B,
And a capacitor (C5) and a coil (L5) connected in series with the contacts at the node B.
[4" claim-type="Currently amended] The method of claim 1,
An out-of-band reflection cancellation intermediate frequency filter circuit having a 22 MHz band of a 55 MHz center frequency to suppress the harmonic components.
[5" claim-type="Currently amended] The method of claim 1,
And the out-of-band frequency is totally reflected so that the signal flows through the band rejection filter to 50 Ω.

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同族专利:

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引用文献:

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公开号 | 申请日 | 公开日 | 申请人 | 专利标题

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法律状态:
1996-12-31|Application filed by 이우복, 사단법인 고등기술연구원연구조합

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1996-12-31|Priority to KR1019960080931A

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1998-10-07|Publication of KR19980061560A

优先权:

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申请号 | 申请日 | 专利标题

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KR1019960080931A|KR19980061560A|1996-12-31|1996-12-31|Intermediate frequency filter circuit for out-of-band reflection cancellation|