KR20140141422A - Filter device - Google Patents

Abstract

The present invention relates to a filter device, comprising: an antenna unit to receive (or transmit) a radio frequency signal; multiple matching units which are connected to the antenna unit and include inductance (L) and capacitance (C) components for respective impedance matching; multiple band amplifying units which are respectively connected to the matching units to amplify signals transmitted through the matching units by each band; a filter means which constitutes an LC resonance circuit by connecting the currently operated band amplifying units to the inductance (L) and capacitance (C) components of the matching units connected to the band amplifying units that are not currently operated among the band amplifying units according to a control signal and includes a changing unit to change the capacitance (C) components of the constituted LC resonance circuit; and a control means to output the control signal to control the filter means according to operation states of the band amplifying units and to input the control signal into the filter means.

Description

FILTER DEVICE

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter device, and more particularly, to a filter device that can simplify a system by removing undesired signals of other bands by utilizing internal elements of the RF transmission / reception system without using separate filter elements.

In general, an RF transceiver or a system on chip (SOC) refers to a system capable of transmitting and receiving a specific signal component of a baseband in the form of an RF signal of an antenna through an antenna.

All transmit and receive systems use separate elements inside or outside the chip or use circuit design techniques for impedance matching with specific antennas.

In a multi-band or multi-standard system, individual matching is required for each band or standard. In order to minimize the influence of signals of different bands on their band, A front surface acoustic wave filter (SAW filter), a duplexer, a triplexer, a band-pass filter, or a band-stop filter An additional device is connected to achieve bandpass or band rejection.

1 is a block diagram of a conventional general multi-band receiver.

1, a conventional multi-band receiver includes an antenna 1 for receiving an RF signal, an antenna 2 for eliminating other signal components from the outside and for passing only a signal of a desired band (a kind of blocker elimination A bandpass filter 2, a matching unit 3 including a plurality of inductors L1, L2 and L3 for impedance matching and a plurality of capacitors C1, C2 and C3; And low-noise amplifiers (LNAs) 4, 5 and 6 connected to the matching unit 3 via pins Pin1, Pin2 and Pin3.

As shown in block A, the low noise amplifiers 4, 5, and 6 use only NMOS transistors (A1), NMOS transistors and PMOS transistors (A2), or two types of NMOS transistors ).

As another conventional multi-band receiver, there are multi-band receivers shown in Figs. 2 and 3, respectively.

2, a plurality of antennas 7, 8.9 are connected to a plurality of SAW filters 10, 11, 12, respectively, and each SAW filter 10, 11, And the matching sections 13, 14 and 15 are connected to the A band low noise amplifier 16, the B band low noise amplifier 17 and the C band low noise amplifier 18, respectively, .

3 includes a tripler 21 connected to a single antenna 20, a plurality of matching units 22, 23, and 24 connected to a triplexer 21, and each matching unit 22, 23 and 24 are connected to the A-band low-noise amplifier 25, the B-band low-noise amplifier 26 and the C-band low-noise amplifier 27, respectively.

As described above, in the conventional RF transmission / reception system, a band-pass filter such as a SAW filter, a diplexer, or a triplexer is installed in order to remove a blocker signal at the time of constructing the input stage, And an additional area is consumed in the RF transceiver or chip.

Disclosure of Invention Technical Problem [8] The present invention has been made to solve the problems of the conventional art as described above, and it is an object of the present invention to eliminate an unwanted signal of another band by using internal elements of the RF transmission / reception system without using a separate filter element And to provide a filter device capable of simplifying the system.

A filter device according to a first aspect of the present invention includes: an antenna unit (110) for receiving (or transmitting) a radio frequency signal; A plurality of matching units 130 connected to the antenna unit 110, each matching unit 130 including an inductance L and a capacitance C for impedance matching; A plurality of band amplifiers connected respectively to the plurality of matching units 130 and amplifying signals transmitted through the matching unit 130 for each band; (L) and a capacitance (C) component of the matching unit 130 connected to the band amplifying unit that is not currently operating among the plurality of band amplifying units to the currently operating band amplifying unit according to the control signal, Filter means constituting a resonance circuit, and including a changing portion for changing a capacitance (C) component in the configured LC resonance circuit; And control means for outputting the control signal for controlling the filter means according to the operation states of the plurality of band amplifying units and inputting the control signal to the filter means.

According to the second aspect of the present invention, the filter means can be configured to have a notch filter characteristic that removes only a specific frequency component by changing the capacitance (C) component in the configured LC resonance circuit .

Further, according to the third aspect of the present invention, the changing portion may be a variable capacitor.

According to a fourth aspect of the present invention, the filter unit further includes a matching unit (130) operating in accordance with a control signal from the control unit and connected to a band amplification unit not currently operating among the plurality of band amplification units, And the inductance L and the capacitance C of the matching unit 130 connected to the currently operating band amplifying unit are cut off from the signal path between the antenna unit 110 and the antenna unit 110, And a plurality of switching elements connected to the ground amplifying part and to the ground terminal on the other side.

According to a fifth aspect of the present invention, the filter unit further includes a filter unit configured to filter the inductance (L) and the capacitance (C) components of the matching unit (130) connected to the band- And can be connected to the input side of the currently operating band amplification unit.

According to a sixth aspect of the present invention, the filter unit further includes a filter unit configured to filter the inductance (L) and the capacitance (C) components of the matching unit (130) connected to the band- It can be connected to the internal circuit side of the currently operating band amplification section.

According to a seventh aspect of the present invention, the filter means further includes a filter unit that filters inductance (L) and capacitance (C) components of the matching unit (130) connected to the band- And can be connected to the output side of the currently operating band amplification section.

According to an eighth aspect of the present invention, the plurality of band amplifying units may be a low-noise amplifier ("LNA").

According to the present invention, it is possible to simplify the system by utilizing the internal elements of the RF transmission / reception system and eliminating unwanted signals in other bands without using a separate filter element.

In particular, according to another aspect of the present invention, by utilizing the elements of the input side matching unit as a notch filter to show band rejection characteristics for unwanted signals of other bands, the deterioration of the system with respect to unwanted signals of other bands . And, since the notch frequency can be changed by adjusting the capacitance (C) component of the changing part, it is easy to cope with the unwanted frequency.

1 is a block diagram of a multi-band receiver according to a first conventional example.
2 is a block diagram of a multi-band receiver according to a second conventional example.
3 is a block diagram of a multi-band receiver according to a third conventional example.
4 is a diagram for explaining the principle of the present invention.
5 is a circuit diagram showing an example of a multi-band receiver to which a filter device is applied, according to an embodiment of the present invention.
6 is a view for explaining an operation example of a multi-band receiver to which a filter device is applied, according to an embodiment of the present invention.
7 is a schematic circuit diagram of a multi-band receiver to which a filter device according to a modification of the present invention is applied.
8 is a schematic circuit configuration diagram of a multi-band receiver to which a filter device according to another modification of the present invention is applied.
9 is a graph showing a gain characteristic of a low noise amplifier of a multi-band receiver to which the filter device of the present invention is applied.
10 is a schematic view illustrating a first application example of the present invention.
FIG. 11A is a second application example of the present invention, and FIG. 11B is a schematic view illustrating a third application example of the present invention.
12 is a graph showing an example of a frequency response (gain characteristic) when a single input is merged.

The details of other embodiments are included in the detailed description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

4 is a diagram for explaining the principle of the present invention.

In Fig. 4, (a) is a schematic view of an LC series resonance circuit when the matching unit is L1 and the changing unit is C1. In FIG. 4A, when the capacitance value of the changing part C1 is changed, Vsource, that is, the impedance when viewed from the antenna end side shows characteristics of a low impedance or short at the LC resonance frequency ( 4 (b)).

In other words, when a notch filter is implemented using the matching unit and LC resonance occurs at the frequency of the block ker signal by using the LC resonance, the block ker signal component is not the receiving end that is currently receiving the wanted signal, The signal is transmitted through the resonant notch, thereby improving the blocker performance.

In one embodiment

5 is a circuit diagram showing an example of a multi-band receiver to which a filter device is applied, according to an embodiment of the present invention. 5, a multi-band receiver to which a filter device according to an embodiment of the present invention is applied includes an antenna unit 40, a plurality of matching units 50, a filter unit 60, a plurality of low noise amplifiers (LNAs) 70, 71 and 72, and control means not shown.

The antenna unit 40 receives a radio frequency signal.

The matching units 50 include an inductance L and a capacitance C for impedance matching for each band. The inductance L and the capacitance C of the matching unit 50 are divided into (1) an inductor L1 as an inductance (L) A capacitor C1 as a capacitance C component is connected in series to the low noise amplifier 70 of the first band via the pin P _IN 1 and (2) in the second band, the inductance L component The inductor L2 as a capacitor and the capacitor C2 as a capacitance component are connected in series and connected to each other in series with the low noise amplifier 71 of the second band via the pin P _IN 2, in the third band, the inductance (L) and an inductor (L3) and capacitance (C) the capacitor (C3) as the component as a component in series connection, to each other in series connection pin (P _iN 3) low-noise amplifier of a third band by a ( 72, respectively.

The filter means 60 is operated in accordance with the control signal inverted through the inverter IV1 and the inverter IV1 for inverting the control signal from the control means so that the inductance between the inductor L1 and the antenna 40 And a second switching element SW2 which is operated in accordance with a control signal from the control means to connect or disconnect between the inductor L1 and the antenna 40. The first switching element SW1 connects / .

The filter means 60 is connected to the capacitor C1 through the capacitor C1 and a second variable capacitor C5 connected between the low-noise amplifier 70 of the first band and the fourth switching element SW4, A first variable capacitor C4 connected to the ground terminal through an intermediary thereof, a second variable capacitor C4 connected to the ground terminal between the first variable capacitor C4 and a fourth switching element SW4 described later, And a third switching element SW3 for blocking the second switching element SW2.

The filter means 60 is operated in accordance with the control signal inverted through the inverter IV1 so as to connect or disconnect the first variable capacitor C4 and the second variable capacitor C5, A second variable capacitor C5 having one end commonly connected to the fourth switching element SW4 and one end of the capacitor C2 and the second band low noise amplifier 71 and the other end connected to the ground terminal, And a third variable capacitor C6 whose one end is commonly connected to the capacitor C3 via the pin P _IN 3 and the low noise amplifier 72 for the third band and whose other end is connected to the ground terminal.

Now, an operation example of a multi-band receiver to which the filter device is applied according to an embodiment of the present invention will be described with reference to FIG.

A radio frequency signal is received from the outside through the antenna unit 40. The received radio frequency signal is impedance matched through a plurality of matching units 50 and transmitted to the low noise amplifiers 70 to 72 of the first to third bands And amplified for each band.

The control means monitors the operation state of each of the low noise amplifiers 70 to 72. If the low noise amplifier 70 of the first band is not operating and the low noise amplifier 71 of the second band is operating, And outputs a band ON signal.

The first band ON signal outputted from the control means is applied to the second and third switching elements SW2 and SW3 and inverted through the inverter Iv1 so that the first and fourth switching elements SW1 , SW4.

The second and third switching devices SW2 and SW3 are turned off to cut off the path between the antenna 40 and the first band inductor L1 and the capacitor C1 of the matching unit 60, The connection between the one variable capacitor C4 and the fourth switching element SW4 and the ground terminal is cut off.

The first and fourth switching devices SW1 and SW4 are turned on to connect one end of the first band inductor L1 of the matching unit 60 to the ground terminal and connect the first variable capacitor C4 to the antenna 40) and the low-noise amplifier 71 for the second band.

Thereby, an LC series resonant circuit composed of the inductor L1 for the first band, the capacitor C1 and the first variable capacitor C4 is formed between the antenna 40 and the low-noise amplifier 71 for the second band , And the LC series resonance circuit thus configured exhibits a notch filter characteristic that removes only a specific frequency component as described in the principle of the present invention by LC series resonance.

Here, the notch filter can be tuned by adjusting the capacitance value of the first variable capacitor C4 so that the frequency becomes a specific frequency (or the frequency at which the blocker signal exists), and the target predetermined frequency component can be tuned to the notch filter Can be removed.

The capacitance value of the first variable capacitor C4 may preferably be adjusted by a control signal of the manual adjustment or control means.

The circuits inside the low-noise amplifier in the band operating as the notch filter are all open (input impedance is high) (for example, by control of the control means) .

That is, by configuring the notch filter by utilizing the inductance (L) component and the capacitance (C) component of the matching section of the band not currently operating, a bandpass filter is no longer needed for the input signal from the antenna section 40 So that each band-specific input is directly merged to simplify the configuration of the multi-band receiver.

In the embodiment illustrated in FIGS. 5 and 6, the filter means 60 can use the inductance (L) component and the capacitance (C) component of the matching portion of the first band as a notch filter. It will be apparent to those skilled in the art that a configuration capable of using the inductance (L) component and the capacitance (C) component of the second band and the third band as a notch filter can be easily conceived with reference to this example, It will be understood that they fall within the scope of the invention.

5 and 6, the filter device of the present invention is applied to a multi-band receiver. However, those skilled in the art will appreciate that the filter device of the present invention can be applied to a multi- Band transceiver and that it is within the scope of the present invention.

Variation example

7 is a schematic circuit diagram of a multi-band receiver to which a filter device according to a modification of the present invention is applied. 7, the configuration of FIGS. 5 and 6 is different from the configuration of FIG. 5 except that the other end of the fourth switch SW4 of the filter means 60-1 is connected to the output terminal of the second band low-noise amplifier 71, Do.

7, the LC series resonance circuit is constructed by connecting the output side of the low-noise amplifier 71 to the inductance (L) component and the capacitance (C) component of the matching section for the first band, The notch filter is implemented on the output side.

8 is a schematic circuit configuration diagram of a multi-band receiver to which a filter device according to another modification of the present invention is applied. In Fig. 8, the configuration of Figs. 5 and 6 differs from that of Figs. 5 and 6 in that the other end of the fourth switch SW4 of the filter means 60-2 is connected to the internal circuit of the second band low-noise amplifier 71, same.

8, the LC series resonance circuit is constructed by connecting the internal circuit of the low-noise amplifier 71 with the inductance (L) component and the capacitance (C) component of the matching section for the first band, And a notch filter connected to the internal circuit of FIG.

9 is a graph showing a gain characteristic of a low noise amplifier of a multi-band receiver to which the filter device of the present invention is applied.

9, the difference between the gain characteristics of the low noise amplifier when the filter means 60 to 60-2 of the filter device of the present invention is operated to implement the notch filter and when the notch filter is not implemented have.

That is, it can be seen that the notch filtering effect is exhibited at the specific frequency by the action of the notch filter, and the target specific frequency component can be removed.

Application example

10 is a schematic view illustrating a first application example of the present invention, and is an application configuration in which the filter device of the present invention is applied to a general common-source low noise amplifier (LNA) 8 to 8).

FIG. 11A is a schematic view illustrating a third application example of the present invention, wherein FIG. 11A is a schematic view illustrating the filter device of the present invention in two bands FIG. 11B shows an example in which notch filters of two bands having LC resonance values of 70 to 110 MHz and 170 to 250 MHz are configured for a single input, and FIG. (The internal configuration of the specific filter device is the configuration of Figs. 5 to 8).

In this case, an example of the frequency response (gain characteristic) when a single input is merged is as shown in FIG. 12. As can be seen from FIG. 12, the frequency component of the 200 MHz band is amplified to obtain a high gain And the blocker component of the 100 MHz band is rejected by the notch filter to have a low gain.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is to be understood, therefore, that the embodiments described above are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than the foregoing description, and the meaning and scope of the claims and their equivalents It is to be understood that all changes and modifications that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims (8)

An antenna unit for receiving (or transmitting) a radio frequency signal;
A plurality of matching units connected to the antenna unit, each matching unit including an inductance (L) and a capacitance (C) component for impedance matching;
A plurality of band amplifiers connected respectively to the plurality of matching units and amplifying the signals transmitted through the matching units for respective bands;
(L) and a capacitance (C) component of a matching unit connected to a band amplification unit that is not currently operating among the plurality of band amplification units, to a currently operating band amplification unit according to a control signal to constitute an LC resonance circuit And a changing section for changing a capacitance (C) component in the configured LC resonant circuit; And
And control means for outputting the control signal for controlling the filter means according to the operation states of the plurality of band amplification units and inputting the control signal to the filter means. The method according to claim 1,
Wherein the filter means comprises:
(C) component in the LC resonant circuit configured as described above, and notch filter characteristic that removes only a specific frequency component by changing the capacitance (C) component in the configured LC resonant circuit. The method according to claim 1 or 2,
Wherein the changing portion is a variable capacitor. The method according to claim 1 or 2,
Wherein the filter means comprises:
And a control unit that operates in accordance with a control signal from the control unit to cut off a signal path between a matching unit connected to a band amplification unit that is not currently operating among the plurality of band amplification units and the antenna unit, And a plurality of switching elements for connecting the inductance (L) and the capacitance (C) components of the matching part connected to the amplifying part to the currently operating band amplifying part and connecting the other end to the grounding part, Filter device. The method according to claim 1 or 2,
Wherein the filter means connects an inductance (L) and a capacitance (C) component of a matching unit connected to a band amplifier unit that is not currently operating among the plurality of band amplifier units to an input side of a currently operating band amplifier unit. The method according to claim 1 or 2,
Wherein the filter means is a filter that connects the inductance (L) and the capacitance (C) components of the matching unit connected to the band amplifying unit that is not currently operating among the plurality of band amplifying units to the internal circuit side of the currently operating band amplifying unit Device. The method according to claim 1 or 2,
Wherein the filter means connects an inductance (L) and a capacitance (C) component of a matching unit connected to a band amplifier unit that is not currently operating among the plurality of band amplifier units to an output side of a currently operating band amplifier unit. The method according to claim 1 or 2,
Wherein the plurality of band amplifiers comprise:
And a low-noise amplifier ("LNA").

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