KR100621831B1 - Hybrid tunable filter device - Google Patents

Abstract

The present invention relates to a hybrid variable filter device, and more particularly, by implementing an integrated VHF band pass filter and a UHF band pass filter as much as possible by using an active element, thereby reducing the number of assembly parts to reduce production labor and cost burden The present invention relates to a hybrid variable filter device capable of simplifying a manufacturing process and improving productivity. A mixed variable filter device according to an embodiment of the present invention includes a passive-LC band pass filter including a plurality of inductors, capacitors, and resistors, and a UHF band signal among RF signals induced in the antenna according to a tuning voltage; First and second active band pass filters for passing signals of the first and second VHF bands of the RF signals induced by the antenna according to the tuning voltage, and first to third input switching elements; A plurality of capacitors and resistors, the first and second active band pass filters, the first to third input switching elements, the first to third output switching elements, the capacitors and resistors constituting the passive-LC band pass filter. The first to third output switching devices may be integrated on-chip.

Tuner, Mixed Variable Filter, Band Pass

Description

Hybrid tunable filter device

1 is a block diagram schematically illustrating a tuner including a conventional filter device.

2 is a schematic view showing a mixed variable filter device according to an embodiment of the present invention.

3A is a diagram illustrating in detail a first active band pass filter according to an embodiment of the present invention.

3B is a diagram illustrating in detail a second active band pass filter according to an embodiment of the present invention.

4 is a detailed block diagram illustrating a passive-LC band pass filter according to an embodiment of the present invention.

***** Explanation of symbols for the main parts of the drawing *****

100: mixed variable filter device

110: first active band pass filter

120: second active band pass filter

130: Passive-LC Band Pass Filter

The present invention relates to a hybrid variable filter device, and more particularly, by implementing an integrated VHF band pass filter and a UHF band pass filter as much as possible by using an active element, thereby reducing the number of assembly parts to reduce production labor and cost burden The present invention relates to a hybrid variable filter device capable of simplifying a manufacturing process and improving productivity.

In general, a tuner is a device that receives a radio frequency (RF) signal through an antenna, converts it into an intermediate frequency (IF) signal, detects it, and separates the video signal into an audio signal. Such a tuner is equipped with a varactor diode that changes the oscillation frequency according to the voltage change by using the property that the capacitance of the diode changes when the voltage is applied in the reverse direction, and selects a TV channel according to the change of the oscillation frequency. Done. At this time, in order to avoid the phenomenon that the capacity ratio of the varactor diode is insufficient due to the wide TV reception band (about 50 to 900 ㎒), the tuner is divided into a VHF (Very High Frequency) band and a UHF (Ultra High Frequency) band. Doing.

A tuner including a conventional filter device will be described with reference to FIG. 1. 1 is a block diagram schematically illustrating a tuner including a conventional filter device.

As the RF signal induced by the antenna 10 passes through the input filter 11, the filter device 20, and the tuner IC 30, only one broadcast frequency is selected, and the selected RF signal is selected from the tuner IC ( 30) In the mixer provided therein, the local oscillator 35 in the form of a voltage controlled oscillator is mixed with the oscillation frequency to output an IF signal. The tuner IC 30 is a voltage controlled oscillator having a reference signal generated from the crystal oscillator 31 and a signal generated by a phase locked loop 36 as a control signal passing only a low frequency through the loop filter 34. The voltage at 35 is controlled to produce a predetermined oscillation frequency. In general, the tuner IC 30 uses 5V and 33V as driving voltages, and transfers data through an I2C inter-bus (BUS) in order to set a phase locked loop at a desired frequency. In addition, an IF filter 33 and a SAW filter 32 for receiving only a channel received in response to the selected TV channel and filtering adjacent channels are removed.

As shown in FIG. 1, the conventional filter device 20 is connected to an input filter 11 for removing a signal other than the TV band from the RF signal induced by the antenna 10 and a signal other than the TV band. A UHF band pass filter 21 for passing a signal in the UHF band among the removed RF signals, and a VHF band pass filter 22 for passing a signal in the VHF band. Here, the VHF band pass filter 22 is composed of two filters each passing a second VHF band signal of a frequency higher than the first VHF band and the first VHF band. Varactor diodes are connected to the input and output terminals of each of the UHF band pass filter 21 and the two VHF band pass filters 22. Since the varactor diodes have a capacitance region adjusted according to the tuning voltage output from the tuning IC 30 and are connected to the UHF band pass filter 21 and the two VHF band pass filters 22 to be used for different frequency bands. , Each has a different capacitance area. That is, the varactor diode used in the lower frequency band has a relatively large capacitance, while the diode required in the upper frequency band has a relatively small capacitance.

The conventional filter device 20 is connected to one end of the tuner IC 30, and passes through the RF signal of the required band by the tuning voltage to be output to the tuner IC (30).

However, since the local voltage controlled oscillator 35 and the filter device 20 control the same with the signal from the loop filter 34, the inductor and varactor used for the local voltage controlled oscillator 35 and the filter device 20 are controlled. The diode must be tuned to have the same characteristics. As a result, there is a problem that the manpower and cost burden increases in the production process. In addition, as shown in the figure, a high voltage of 33 V is required to control the varactor diode, which requires a separate high voltage generator. In addition, the use of a large number of external passive components, the inductor and the varactor diode, increases the overall cost and increases the mounting area.

Therefore, the technical problem of the present invention is to integrate the VHF band pass filter and the UHF band pass filter to the IC as much as possible by using the active element, thereby reducing the number of assembly parts, reducing the production manpower and cost burden, and tuning the external passive elements. It is to provide a hybrid variable filter device that eliminates the need to simplify the manufacturing process to increase productivity and reduce the mounting area.

The technical problem to be achieved by the present invention is not limited to the technical problem mentioned above, other technical problems that are not mentioned will be clearly understood by those skilled in the art from the following description. Could be.

Mixed variable filter device according to an embodiment of the present invention for achieving the above technical problem is composed of a plurality of inductors, capacitors, resistors, and the UHF band of the RF signal is induced in the antenna according to the tuning voltage A passive-LC band pass filter for passing through, a first active band pass filter for passing a signal in a first VHF band of the RF signal induced in the antenna according to the tuning voltage, and a pass in the antenna according to the tuning voltage A second active band pass filter for passing a signal of a second VHF band having a frequency higher than the first VHF band among the incoming RF signals, and the passive-LC band pass filter and the first and second active band pass filters. First to third input switching elements connected and switched to an input terminal, the passive-LC band pass filter, and the first and second active bands. A plurality of capacitors and resistors, the first and second active band pass filters constituting the passive-LC band pass filter, the first to third output switching elements being connected to and switched at an output of the pass filter. The first to third input switching devices and the first to third output switching devices may be integrated on-chip.

In the mixed variable filter device according to an embodiment of the present invention, the first VHF band is preferably 48 to 160 MHz, and the second VHF band is preferably 160 to 450 MHz.

In the hybrid variable filter device according to an embodiment of the present invention, the first and second active band pass filters are preferably composed of a plurality of operational amplifiers, capacitors, and resistors.

In the hybrid variable filter device according to an embodiment of the present invention, the -3dB bandwidth of the first active band pass filter is preferably 18 MHz to 30 MHz.

In the hybrid variable filter device according to an embodiment of the present invention, the -3dB bandwidth of the second active band pass filter is preferably 18 MHz to 30 MHz.

In the mixed variable filter device according to the embodiment of the present invention, the -3dB bandwidth of the passive-LC band pass filter is preferably 18 MHz to 30 MHz.

Mixed variable filter device according to another embodiment of the present invention for achieving the above-described technical problem is composed of a plurality of bonding wire inductor, capacitor, resistor, and the UHF band of the RF signal is induced in the antenna according to the tuning voltage A passive-LC band pass filter for passing a signal, a first active band pass filter for passing a signal of a first VHF band among RF signals induced in the antenna according to the tuning voltage, and the antenna according to the tuning voltage A second active band pass filter for passing a signal of a second VHF band having a frequency higher than the first VHF band among the RF signals that are induced in the first pass, the passive-LC band pass filter, and the first and second active band pass First to third input switching elements connected and switched to an input of the filter, the passive-LC band pass filter, the first and It is characterized in that the integrated on-chip (In-Chip) including the first to third output switching device is connected to the output terminal of the second active band pass filter is switched.

In the mixed variable filter device according to another embodiment of the present invention, the first VHF band is preferably 48 to 160 MHz, and the second VHF band is preferably 160 to 450 MHz.

In the mixed variable filter device according to another embodiment of the present invention, the first and second active band pass filters are preferably composed of a plurality of operational amplifiers, capacitors, and resistors.

In the mixed variable filter device according to another embodiment of the present invention, the -3dB bandwidth of the first active band pass filter is preferably 18 MHz to 30 MHz.

In the hybrid variable filter device according to another embodiment of the present invention, the -3dB bandwidth of the second active band pass filter is preferably 18 MHz to 30 MHz.

In the hybrid variable filter device according to another embodiment of the present invention, the -3 dB bandwidth of the passive-LC band pass filter is preferably 18 MHz to 30 MHz.

Specific details of other embodiments are included in the detailed description and the drawings. Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. Like reference numerals refer to like elements throughout.

A mixed variable filter device according to an embodiment of the present invention will be described with reference to FIG. 2. 2 is a schematic view showing a mixed variable filter device according to an embodiment of the present invention.

As shown in FIG. 2, the hybrid variable filter device 100 according to an embodiment of the present invention receives an RF input signal and outputs an RF output signal having a predetermined frequency band. 110, a second active band pass filter 120, and a passive-LC band pass filter 130.

The first active band pass filter 110 passes a signal of the first VHF band among the RF signals induced by the antenna according to the tuning voltage, and the second active band pass filter 120 is induced into the antenna according to the tuning voltage. Passes a signal in a second VHF band of a frequency higher than the first VHF band of the incoming RF signal. Passive-LC band pass filter 130 is composed of a plurality of passive elements, inductors, capacitors, resistors, and passes the UHF band of the RF signal is induced in the antenna according to the tuning voltage.

First to third input switching devices 140, 141, and 142 are connected and switched to input terminals of the first and second active band pass filters 110 and 120 and the passive-LC band pass filter 130, respectively. The first to third output switching devices 150, 151, and 152 are connected and switched to the output terminal, respectively.

Here, the inductor constituting the passive-LC band pass filter 130 is a passive element, which is difficult to integrate on-chip because device characteristics may change or act as a coupling generating factor depending on the configuration. Accordingly, the hybrid variable filter device 100 of the present invention is an embodiment in which all components except the inductor constituting the passive-LC band pass filter 130 are integrated on-chip and the passive-LC band. The inductor constituting the pass filter 130 is included as an on-chip as a bonding wire inductor and implemented in two of the other embodiments integrating the inductor to increase user selectivity.

Thus, according to another embodiment of the invention, the passive-LC band pass filter 130, the first and second active band pass filters 110, 120, and the first to third input switching elements 140, 141, 142. ), A mixed variable filter device 100 integrated on-chip including first to third output switching elements 150, 151, and 152 is provided. Here, the passive-LC band pass filter 130 is composed of a plurality of bonding wire inductors, capacitors, and resistors, and is designed to pass a signal in the UHF band among RF signals induced by the antenna according to the tuning voltage.

In addition, the first and second active band pass filters 110 and 120 of the present invention are active filters including an active element, an active-RC filter composed of a passive element capacitor and a resistor and an op amp with an amplifying action, MOSFET And a MOSFET-C filter composed of a capacitor, a transconductor that outputs a current multiplied by a Gm value, and a Gm-C filter composed of a capacitor and a passband frequency of the filter determined by the Gm / C value. And, most preferably, consists of an active-RC band pass filter combining a plurality of capacitors, resistors, and op amps.

Filter design is carried out using a transfer function or a loss function. Looking at the process of realizing an active filter having a desired frequency characteristic, the designer outlines the steps of obtaining a transfer function that satisfies the desired frequency characteristic. Factoring and dividing into first and second terms, designing a filter that realizes its characteristics according to the active filter design method for each factored first or second rational equation, and cascading each of these blocks Therefore, it can be divided into designing a desired filter and performing scaling on frequency shift and impedance shift.

In this case, various types of passband characteristics may be implemented according to the type of transfer function used. The most representative ones are Butterworth type, Chebyshev type, and Bessel type. Butterworth type filters have a flat passband but poor skirt characteristics. Although the Bessel type filter can realize group flatness characteristics as flat as possible in the frequency domain, it is difficult to realize a sudden attenuation characteristic in the attenuation band because the skirt characteristic is not as good as in the Butterworth type filter. Chebyshev type filters, on the other hand, have very good skirting characteristics.

A first and second active band pass filter according to an embodiment of the present invention will be described with reference to FIGS. 3A and 3B. 3A is a detailed block diagram illustrating a first active band pass filter according to an embodiment of the present invention, and FIG. 3B is a detailed block diagram illustrating a second active band pass filter according to an embodiment of the present invention.

The first active band pass filter 110 according to an embodiment of the present invention is a type II Chebyshev type having three low one high orders, as shown in FIG. 3A, and includes a high pass filter (HPF) and a low pass filter. (LPF), op amps OP1 to OP6 for amplifying signals, variable resistors R1 and R2 and parallel capacitors C1 to C4 connected in parallel to the op amps OP1, OP3, OP4, and OP6. ) And resistors R3 to R14.

In addition, the second active band pass filter 120 according to an embodiment of the present invention is a type II Chebyshev type having a 3 low 1 high order, as shown in FIG. 3B, and has a high pass filter (HPF ′). A low pass filter (LPF '), the op amps (OP1' to OP6 ') for amplifying the signal, and the variable resistor (R1) connected in parallel to the op amps (OP1', OP3 ', OP4', OP6 ') ', R2'), variable capacitors C1 'to C4', and resistors R3 'to R14'.

Variable resistors R1, R2, R1 ', and R2' and variable capacitors C1 to C4, C1 'to C4' included in the high pass filters HPF and HPF 'and the low pass filters LPF and LPF', respectively. By adjusting, the center frequency (fo), the quality factor (Q), and the pass bandwidth can be optimized.

In addition, -3 so that the center frequency of each of the first and second active band pass filters 110 and 120 varies in a range of approximately 48 to 160 MHz in the first VHF band and approximately 160 to 450 MHz in the second VHF band. It is desirable that the bandwidth be designed to be between 18 MHz and 30 MHz. More preferably, the -3Hz bandwidth is designed to be at a level of about 20 MHz.

In general, since the reception band per TV channel is 6 MHz, by securing a -3 dB bandwidth of 18 MHz to 30 MHz, the three-channel signal can be passed while the bandwidth is variable within the range of 48 to 160 MHz and 160 to 450 MHz. have.

A passive-LC band pass filter of the present invention will be described with reference to FIG. 4 is a detailed block diagram illustrating a passive-LC band pass filter according to an embodiment of the present invention.

Passive-LC band pass filter 130 according to an embodiment of the present invention is a filter of the secondary vessel type, as shown in Figure 4, the inductor (L1, L2, L3) and the variable capacitor (C1, C2, C3) It is composed of

The variable capacitors C1, C2, and C3 can be adjusted to optimize the center frequency (fo), quality factor (Q), and passband.

In addition, the UHF band, which is the pass band of the passive-LC band pass filter 130, is preferably designed such that the -3 kHz bandwidth is 18 MHz to 30 MHz so that the center frequency is varied in the range of approximately 450 to 860 MHz. Do. More preferably, the -3Hz bandwidth is designed to be at a level of about 20 MHz.

In general, since the reception band per TV channel is 6 MHz, by securing a -3 dB bandwidth of 18 MHz to 30 MHz, it is possible to pass three channels of signals while the bandwidth is variable within the range of 450 to 860 MHz.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. I can understand that. Therefore, since the embodiments described above are provided to fully inform the scope of the invention to those skilled in the art, it should be understood that they are exemplary in all respects and not limited. The invention is only defined by the scope of the claims.

The hybrid variable filter device according to an embodiment of the present invention made as described above implements the VHF band pass filter and the UHF band pass filter to the IC as much as possible by using an active element, thereby reducing the number of assembly parts and producing a workforce. And it can reduce the cost burden, simplify the manufacturing process to improve productivity and minimize the mounting area.

Claims (12)

A passive-LC band pass filter comprising a plurality of inductors, capacitors, and resistors, and passing a signal in a UHF band among RF signals induced by the antenna according to a tuning voltage; A first active band pass filter for passing a signal of a first VHF band among RF signals induced by the antenna according to the tuning voltage; A second active band pass filter configured to pass a signal of a second VHF band having a frequency higher than the first VHF band among the RF signals induced by the antenna according to the tuning voltage; First to third input switching elements connected and switched to input terminals of the passive-LC band pass filter and the first and second active band pass filters; And A first to third output switching element connected and switched to output terminals of the passive-LC band pass filter and the first and second active band pass filters, The plurality of capacitors and resistors constituting the passive-LC band pass filter, the first and second active band pass filters, the first to third input switching elements, and the first to third output switching elements are on chips. Hybrid variable filter device, characterized in that integrated into the (Chip). The method of claim 1, The first VHF band is 48 ~ 160 MHz, the second VHF band is a mixed variable filter device, characterized in that 160 ~ 450 MHz. The method of claim 1, And the first and second active band pass filters comprise a plurality of operational amplifiers, capacitors and resistors. The method of claim 1, -3 dB bandwidth of the first active band pass filter is a hybrid variable filter device, characterized in that 18 MHz ~ 30 MHz. The method of claim 1, -3 dB bandwidth of the second active band pass filter is a hybrid variable filter device, characterized in that 18 MHz ~ 30 MHz. The method of claim 1, -3 dB bandwidth of the passive-LC band pass filter is a hybrid variable filter device, characterized in that 18 MHz to 30 MHz. A passive-LC band pass filter composed of a plurality of bonding wire inductors, capacitors, and resistors, and passing a signal in a UHF band among RF signals induced by the antenna according to a tuning voltage; A first active band pass filter for passing a signal of a first VHF band among RF signals induced by the antenna according to the tuning voltage; A second active band pass filter configured to pass a signal of a second VHF band having a frequency higher than the first VHF band among the RF signals induced by the antenna according to the tuning voltage; First to third input switching elements connected and switched to input terminals of the passive-LC band pass filter and the first and second active band pass filters; And A hybrid type comprising on-chip including first to third output switching elements connected to and switched from the passive-LC band pass filter and the output terminals of the first and second active band pass filters Variable filter device. The method of claim 4, wherein The first VHF band is 48 ~ 160 MHz, the second VHF band is a mixed variable filter device, characterized in that 160 ~ 450 MHz. The method of claim 4, wherein And the first and second active band pass filters comprise a plurality of operational amplifiers, capacitors and resistors. The method of claim 1, -3 dB bandwidth of the first active band pass filter is a hybrid variable filter device, characterized in that 18 MHz ~ 30 MHz. The method of claim 1, -3 dB bandwidth of the second active band pass filter is a hybrid variable filter device, characterized in that 18 MHz ~ 30 MHz. The method of claim 1, -3 dB bandwidth of the passive-LC band pass filter is a hybrid variable filter device, characterized in that 18 MHz to 30 MHz.

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