KR20080094218A - Filter circuit - Google Patents

Abstract

A filter circuit is provided to improve filtering performance of the filter circuit by primarily blocking unnecessary signal components close to a pass band and then passing a desired signal using a BPF. A filter circuit includes a band rejection filter(11) and a BPF(Band Pass Filter)(12). The band rejection filter is arranged between a signal input side and a signal receiver side. The band rejection filters are formed on different paths outputting different signals. The BPF is connected to an output terminal of the respective band rejection filters. The signal input side is a tuner circuit, which selects a specific signal from received signals. The signal receiver side is a demodulator circuit, which converts a modulated signal to an original signal.

Description

Filter Circuits {FILTER CIRCUIT}

1 is a block diagram schematically showing a configuration according to an embodiment of the present invention.

Figure 2 is a block diagram showing in more detail the configuration according to an embodiment of the present invention.

3 is a circuit diagram according to an embodiment of the present invention.

<Description of Signs of Major Parts of Drawings>

10: oiling cap opening and closing control device

1: battery

5a: L terminal

11: opening and closing means 1

12: oil cap switch

13: opening and closing means 2

The present invention relates to a filter circuit.

In general, the filter circuit is a circuit that constitutes a device for passing the vibration current of a specific signal. The filter circuit may be applied to various fields, but may be applied to a broadcasting system such as a television receiver or a radio receiver.

In such a terrestrial digital broadcasting system, a large amount of video, audio, and data is modulated by 8-VSB (Vestial Side Band) and transmitted through a 6 MHz channel such as NTSC. In addition, digital terrestrial broadcasting transmits about 19 Mbps of data on a 6 MHz channel, and digital cable broadcasting transmits about 38 Mbps of data. The signal transmitted in this manner is received through the antenna of the receiver, and is tuned through an input filter, an amplifier circuit, and a tuning circuit.

As described above, the signal received through the receiver is filtered with the desired band according to the bandwidth of the filter disposed in the progress path. However, in the case of the conventional filter, a signal corresponding to an adjacent channel other than the desired signal is included without filtering. There is a problem going on.

In particular, conventionally, a capacitor and a resistor are arranged in series between the tuning circuit and the demodulation circuit to remove the signal DC component that proceeds. Then, the signal components transferred from the actual tuning circuit to the demodulation circuit include adjacent unnecessary signals in addition to the original signals to be obtained, which affects the original signals.

The present invention can improve the blocking performance of unnecessary signal components.

According to an aspect of the present invention, there is provided a band cut filter provided between a signal input side and a signal input side and provided in different paths through which different signals are output; And a band pass filter at an output terminal of each band cut filter.

Here, the signal input side receives a myriad of signals floating in the free space through an antenna, selects a specific signal of the received signal through a tuner circuit, and then converts it into a desired original signal through a demodulation circuit, the tuner Circuits, in particular tuning ICs.

The signal input side may be a demodulation circuit, and in particular, may be a VSB-IC. In this case, the VSB means a residual side band.

For reference, when the VSB amplitude-modulates a voice or other signal wave, the amplitude-modulated signal spectrum is preserved as a side wave on both sides of the original signal wave with respect to the carrier signal. Transmission of this as it is is the two-side band (DSB) transmission, the transmission of only one of the upper band or the lower band is a single-side band (SSB) transmission, and removes most of one side band and the remaining part and the other Transmitting the sideband is a residual sideband transmission. The VSB-IC demodulates the modulated signal transmitted through this transmission scheme.

The bandpass filter may be an inductor and a capacitor arranged in parallel on each signal path. In this case, the band cut filters may be provided on signal propagation paths having different phases, and capacitors and resistors may be disposed in parallel between the input terminal and the signal input side of each band cut filter to remove direct current components. Can be.

On the other hand, the band pass filter may be arranged in parallel between the capacitor and the interduct between the signal input side is connected to the output terminal of the band-pass filter.

The bandpass filter is a circuit for passing a signal present in a specific range of signals at a receiver and removing a signal outside this range.

PF BPF1: Selected signal to be received from amplified signal is composed by using inductor and condenser, but surface acoustic wave (SAW) filter may be used. SAW filters include ultra narrowband filters and wideband filters, which are selected according to the characteristics of the radio call receiver or the region of use.

BPF2: Removes unwanted signals from the signal components output from the intermediate frequency amplifier and passes the desired signals (primary intermediate signals).

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings, in the accompanying drawings, Figure 1 is a block diagram showing a brief configuration according to an embodiment of the present invention, Figure 2 FIG. 3 is a block diagram illustrating a configuration according to an embodiment of the present invention in detail. FIG. 3 is a circuit diagram according to an embodiment of the present invention, and reference numeral 10 denotes a filter circuit of the present invention.

1 to 3, the present invention provides a band-block for blocking only unnecessary signals in different paths through which signals having different phases provided between the signal input side 1 and the signal input side 2 travel. Each filter 11 is provided, but a band pass filter 12 for passing only a desired signal to the output terminal of each band cut filter 11 may be provided in parallel.

Here, the signal input side 1 receives a myriad of signals floating in free space through an antenna, selects a specific signal among the received signals through a tuner circuit, and converts it into a desired original signal through a demodulation circuit. The tuner circuit in the path, in particular the tuning IC.

On the other hand, the signal input side 2 is a demodulation circuit, in particular, VSB-IC. For reference, the VSB refers to a residual side band, and the VSB-IC is an IC chip for performing 8-step VSB demodulation.

On the other hand, the band cut filter 11 includes an inductor 1 (L1) and a capacitor 1 (C1) arranged in parallel on each signal path. In this case, the band cut filter 11 is disposed on a signal propagation path having different phases.

In this way, inductor 1 (L1) passes a low signal, capacitor 1 (C1) inversely passes a high signal. That is, inductor 1 (L1) and capacitor 1 (C1) show the opposite signal characteristics due to the instantaneous electromagnetic energy accumulation and emission characteristics.

In the present invention, since the inductor 1 (L1) and the capacitor 1 (C1) are arranged in parallel with the traveling signal, the inductor 1 (L1) on the same signal is not allowed to pass, so that the capacitor 1 (C1) to pass through Thus, the pass characteristic is determined to be the stronger of the two characteristics. In this way, since the signal of the specific region is blocked, the adjacent signal region can be blocked in addition to the desired signal.

In addition, a capacitor C and a resistor R for removing a DC component from a traveling signal are disposed in parallel between the input terminal of each band cut filter 11 and the signal input side 1. In this case, the direct current component can be removed from the signal component provided from the signal input side 1, thereby reducing the noise.

On the other hand, in the band pass filter 12, the capacitor C2 and the interleat L2 are disposed in parallel between the signal input side 2 to which the output terminals of the band cut filter 11 are connected.

In this case, too, the inductor 2 (L2) passes the low signal and the capacitor 2 (C2) passes the high signal on the contrary, so that the pass characteristic is determined to be the stronger of the two characteristics. In this way, since only a signal of a specific region is passed, only a desired signal can be provided to the signal input side 2.

While the invention has been described and illustrated in connection with a preferred embodiment for illustrating the principles of the invention, the invention is not limited to the configuration and operation as such is shown and described. Rather, those skilled in the art will appreciate that many changes and modifications to the present invention are possible without departing from the spirit and scope of the appended claims. Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

According to the present invention, the unnecessary signal portion adjacent to the desired signal (frequency) is first blocked through the band pass filter, and then only the desired signal is passed through the band pass filter, thereby improving the performance of the filter.

Claims (6)

A band cut filter provided between the signal input side and the signal input side and provided in different paths through which different signals are output; And And a band pass filter provided at an output end of each band cut filter. The method of claim 1, wherein the signal input side A filter circuit, characterized in that the tuner circuit for selecting a specific signal of the received signal. The method of claim 1, wherein the signal input side is A demodulation circuit for converting a modulated signal into an original signal. The filter of claim 1, wherein the band pass filter A filter circuit comprising an inductor and a capacitor arranged in parallel on each signal path. The method of claim 1, wherein the band pass filter And a capacitor and an interstack arranged in parallel between the signal input side to which the output terminal of the band cut filter is connected. The method of claim 1, And said other signals are adjacent signals different in signal.

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