KR200248235Y1 - Digital hopping filter - Google Patents

Abstract

The present invention relates to a digital hopping filter that hops according to the frequency hopping pattern of the system while maintaining a constant pass frequency band of the filter. When the frequency band of the channel used is changed, it is composed of a matching circuit and a resonance circuit. In a digital hopping filter comprising two tuning circuits which electronically pass a specific frequency every time, and a control unit which outputs an on / off control signal so that the filter is tuned to a frequency band desired by the user, three coupling capacitors are T. Connect two coupling capacitors in series so as to be interconnected in the shape of a child, and connect the other coupling capacitors in parallel therebetween, and connect one or more coupling capacitors in parallel with the parallel coupling capacitors connected in parallel, Electronic switch to each of the coupling capacitors connected in parallel Consisting of a coupling circuit for connecting the first tuning circuit and the second tuning circuit in the form of a T-shape to switch the elements of the coupling circuit that connects the tuning circuit and the tuning circuit to easily change the coupling coefficient of the coupling circuit according to the frequency. By adjusting, the characteristic deviation in the low frequency band and the high frequency band is reduced to provide a digital hopping filter with uniform characteristics and improving the productivity of the digital hopping filter.

Description

Digital hopping filter

The present invention relates to a digital filter, and more particularly, to a digital hopping filter that hops according to a frequency hopping pattern of a system while maintaining a constant pass frequency band of a center frequency of the filter.

Generally, a filter is an apparatus for removing unnecessary frequency components of a signal in a signal processing system that analyzes and selects frequency components of a signal, amplifies, demodulates, distorts, and removes noise.

In particular, the noise flow generated at the output of the transmitter during transmission of the communication device.

(Noise Floor) interferes with the reception signal band of other equipment adjacent to the transmission frequency, which reduces the reception sensitivity of other equipment located in the same place. The small transmission and reception frequencies interfere with the reception.

Therefore, as described above, in order to reduce the reception sensitivity and reception disturbance caused by the transmission and reception of the communication device, a filter which reduces the reception interruption signal by giving a steep attenuation to signals outside the magnetic band is used. The filter of FIG. 1 to FIG. 2 will be described as follows.

1 is a basic circuit diagram of a filter used in a communication device.

2A is a variable inductor resonant circuit diagram.

2B is a variable capacitor resonant circuit diagram.

2C is a voltage variable capacitance resonant circuit diagram.

2D is a pin diode switch resonant circuit diagram.

Referring to FIG. 1, a filter most commonly used in a communication device includes a coupling circuit 300 connecting two resonance circuits 130 and 230, and two matching circuits 110 and 210 to lower input / output impedance. It consists of a double tuning circuit consisting of).

The coupling circuit 300 uses a capacitor in order to simplify the circuit, and the coupling circuit 300 may be configured by using an inductor or a transformer depending on the circuit.

However, the basic circuit as described above is the basic circuit of the filter for one frequency band, and since the actual communication device is used in the wide band frequency, the center frequency of the filter must also move according to the frequency of the channel used to configure the filter. It is inevitable to change the element value of the circuit.

Therefore, the inductor or capacitor constituting the resonant circuit of the basic circuit is configured to be variable as shown in Figs. 2a to 2b, so that it is manually variable whenever the frequency band of the use channel is changed, or a voltage-variable capacitor diode as shown in Fig. 2c, A plurality of pin diode switches SW31, SW32, SW33, such as 2d, are used to electronically change the element value of the resonant circuit to move the center frequency of the filter.

However, such a filter shifts the center frequency of the filter by manually changing only the inductor or capacitor constituting the resonant circuit or electronically changing the element value of the resonant circuit, so that characteristics such as bandwidth and insertion loss are matched with the coupling circuit. Due to the frequency characteristics of the circuit, the characteristic deviation in the low frequency band and the high frequency band is inevitably large, and there is a problem that it is difficult to adjust the deviation so that the characteristic deviation can be maintained as a uniform characteristic.

In addition, the relatively narrow band (the band within 20% of the intermediate frequency range) is not a big problem, but in the band above 30%, it is adjusted by lowering the band with better characteristics to compensate for the band underperforming. However, there is a problem in that productivity is lowered because the device values of the matching circuit and the coupling circuit must be changed and adjusted several times.

In particular, in order to change the device value of the coupling circuit, since the device value is changed by manually changing the device value or by changing the tap value of the matching circuit, it is difficult to adjust the filter of uniform characteristics.

The present invention has been made in view of the above problems, and its object is to switch the elements of the coupling circuit connecting the tuning circuit and the tuning circuit so that the coupling coefficient of the coupling circuit can be easily adjusted according to the frequency, and thus the low frequency band. To reduce the characteristic deviation in the high frequency band and to provide a digital hopping filter of uniform characteristics, and to improve the productivity of the digital hopping filter.

1 is a basic circuit diagram of a filter used in a communication device.

2A is a variable inductor resonant circuit diagram.

2b is a variable capacitor resonant circuit diagram.

2C is a voltage variable capacitance resonant circuit diagram.

2D is a pin diode switch resonant circuit diagram.

3 is a detailed circuit diagram illustrating a digital hopping filter of the present invention.

FIG. 4 is a circuit diagram of the coupling circuit of FIG. 3 converted from a T letter to a Π letter.

FIG. 5 is a circuit diagram illustrating the coupling circuit of FIG. 3 by connecting a field-effect transistor (FET) switch in parallel.

FIG. 6 is a circuit diagram illustrating the coupling circuit of FIG. 3 by connecting a transistor switch in parallel.

FIG. 7 is a circuit diagram illustrating the coupling circuit of FIG. 3 by connecting FET switches in parallel and in series.

* Description of the symbols for the main parts of the drawings *

10: first tuning circuit 20: second tuning circuit

30: coupling circuit 40: control unit

11: first matching circuit 21: second matching circuit

Configuration of the present invention for achieving the above object is made as follows.

It consists of a matching circuit and a resonant circuit. Two tuning circuits that electronically pass a specific frequency whenever the frequency band of the used channel is changed. In the digital hopping filter,

Two coupling capacitors are connected in series so that three coupling capacitors are interconnected in a T-shape, and another coupling capacitor is connected in parallel between them, and another coupling capacitor is connected to the parallel coupling capacitor connected in parallel. It is characterized in that the coupling circuit for connecting the first tuning circuit and the second tuning circuit in a T-shape by connecting an electronic switch to each of the coupling capacitors connected in parallel and connected in parallel.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the present invention will be described in detail.

3 is a detailed circuit diagram illustrating a digital hopping filter of the present invention.

FIG. 4 is a circuit diagram of the coupling circuit of FIG. 3 converted from a T letter to a Π letter.

FIG. 5 is a circuit diagram illustrating the coupling circuit of FIG. 3 by connecting a field-effect transistor (FET) switch in parallel.

FIG. 6 is a circuit diagram illustrating the coupling circuit of FIG. 3 by connecting a transistor switch in parallel.

FIG. 7 is a circuit diagram illustrating the coupling circuit of FIG. 3 by connecting FET switches in parallel and in series.

Referring to FIG. 3, the digital hopping filter of the present invention includes two first tuning circuits 10 and a second tuning circuit 20, a coupling circuit 30, and a controller 40 having the same structure. consist of.

The first tuning circuit 10 includes the first matching circuit 11 and the first resonant circuit 13 to resonate electronically with a specific frequency whenever the frequency band of the use channel is changed.

The first resonant circuit 13 includes a plurality of resonant capacitors C1 and C2... C10 and a plurality of pin diode switches SW1 and SW2... The plurality of resonant capacitors C1, C2... C10 are connected in parallel, and then the pin diode switch is connected to each of the plurality of resonant capacitors to turn on / off the pin diode switch. The resonance coefficient is changed according to the off state.

The pin diode switches SW1 and SW2... SW10 connect two pin diodes, that is, the first and second pin diodes D1 and D2 in series, and the two pins First and second resistors R1 and R2 are respectively connected in parallel to both ends of the diodes D1 and D2, and one side of the third resistor R3 is connected to the anode side of the first pin diode D1. One side of the fourth resistor R4 is connected to the cathode side of the second pin diode D2, and the 28th capacitor C28 and the 29th capacitor (C28) are connected to one side of the first and second resistors R1 and R2. One side of C29 is connected, the other side of the 28th capacitor C28 and the 29th capacitor C29 is grounded, the other side of the third resistor R3 is connected to a reference voltage, and the fourth resistor R4 The other side of the) is connected to the control unit 40 is turned on / off according to the electrical signal applied from the control unit 40.

For example, the first pin diode switch SW1 has a voltage sufficiently lower than the reference voltage Vbb to the pin diodes D1 and D2 connected in series with the first resonant capacitor C1. When applied to the current in the forward direction is applied 'on', when a voltage higher than the reference voltage Vbb is applied to the first pin diode switch (SW1) the reverse bias is applied to the 'off' state.

The matching circuit 11 consists of connecting another inductor L2 to the tap of the first inductor L1 to increase the selectivity of the filter circuit.

The second tuning circuit 20 has a second matching circuit 21 and a second configuration having the same configuration as the first matching circuit 11 and the first resonant circuit 13 of the first tuning circuit 10. The resonant circuit 23 is electrically resonated at a specific frequency whenever the frequency band of the use channel is changed.

The coupling circuit 30 connects the first tuning circuit 10 and the second tuning circuit 20 to electronic devices, and connects an electronic switch for selecting the electronic devices, Change the coupling coefficient.

The coupling circuit 30 connects the twenty-first coupling capacitor C21 and the twenty-second coupling capacitor C22 in series, and connects the twenty-third coupling capacitor C23 between the three coupling capacitors C21, C22, and the like. C23 is interconnected in a T-shape, the other side of the twenty-first coupling capacitor C21 is connected to the first matching circuit 11 of the first tuning circuit 10, and the twenty-second coupling capacitor C22 The other side of) is connected to the second matching circuit 21 of the second tuning circuit 20, and finally two coupling capacitors, i.e., 24 and 25 couplings, in parallel to the 23rd coupling capacitor C23. Connect capacitors C24 and C25.

In this case, an electronic switch, that is, a pin diode switch of the first resonant circuit 13, is connected to the 23rd, 24th and 25th coupling capacitors C23, C24, and C25 connected in parallel. Connect (SW21, SW22, SW23) respectively.

In addition, three coupling capacitors having a T-shape may be substituted with a Π-shape as shown in FIG. 4.

Referring to FIG. 4, three coupling capacitors connected to each other in the T-shape, that is, the 21st, 22nd and 23rd coupling capacitors C21, C22, and C23 according to a conversion formula derived from Kirchhoff's law, are used. The other two coupling capacitors (C22`, C23`) are connected in parallel to the coupling capacitor (C21`) in the form of Π, and one in the two coupling capacitors (C22`, C23`) connected in parallel. The other coupling capacitors C32 and C33 may be connected in parallel, and an electronic switch may be connected to each of the coupling capacitors.

Accordingly, the coupling circuit converts the coupling capacitor of the T-shape to connect the first tuning circuit 10 and the second tuning circuit 20 to the coupling capacitor of the? -Shape.

In addition, the pin diode switch of the coupling circuit 30 may be configured as a FET switch as shown in FIG.

Referring to FIG. 5, three capacitors 23 connected in parallel to the twenty-third coupling capacitor C23 and the twenty-third coupling capacitor C23, that is, the twenty-fourth and twenty-fifth coupling capacitors C24 and C25 are connected. Instead of the four pin diode switches SW21, SW22, and SW23, three FET switches having the same structure, that is, the 24th, 25th, and 26th FET switches SW24, SW25, and SW26 are respectively connected.

The twenty-fifth switch SW25 connects the drain D side of the FET to one side of the twenty-fourth coupling capacitor C24 and connects a fifth resistor R5 connected in series to the third inductor L3 to the FET. A sixth resistor R6 connected in series with the fourth inductor L4 to the drain D side of the FET, and the source S side of the FET grounded; The thirty-third capacitor C30 and the thirty-first capacitor C31 connected in series between the fifth resistor R5 and the sixth resistor R6 are connected, and the reference voltage Vbb is connected to one side of the fourth inductor L4. And the one side of the third inductor (L3) is connected to the control unit 40 is turned on / off according to the electrical signal applied from the control unit (40).

For example, if the gate applied voltage is 'high' while the Vbb voltage is supplied to the drain terminal of the FET, current is applied from the drain to the source to 'on', and if the gate applied voltage is 'low', the current is blocked. It becomes 'off'.

In addition, the FET switch may be configured using a transistor instead of the FET as shown in FIG.

Referring to FIG. 6, the collector C side of the transistor is connected to one side of the 24th coupling capacitor C24, and the fifth resistor R5 connected in series to the third inductor L3 is connected to the base of the transistor ( The sixth resistor R6 connected in series with the fourth inductor L4 to the collector C side of the transistor, and the emitter E side of the transistor is grounded. A thirty-second capacitor C30 and a thirty-first capacitor C31 connected in series between the fifth resistor R5 and the sixth resistor R6 are connected, and a reference voltage Vbb is connected to one side of the fourth inductor L4. And one side of the third inductor L3 is connected to the controller 40 so as to be turned on / off according to an electrical signal applied from the controller 40.

In addition, the coupling circuit 30 may be configured by connecting the coupling capacitor in series and parallel, as shown in FIG.

Referring to FIG. 7, the three coupling capacitors C21, C22, and C23 are connected by connecting the twenty-first coupling capacitor C21 and the twenty-second coupling capacitor C22 in series, and connecting the twenty-third coupling capacitor C23 therebetween. ) Are interconnected in a T-shape, and two coupling capacitors, that is, the 24th and 25th coupling capacitors C24 and C25, are connected in parallel to the 23rd coupling capacitor C23.

In addition, after the 26th coupling capacitor C26 and the 27th coupling capacitor C27 are connected in series, two coupling capacitors connected in series, that is, the 21st coupling capacitor C21 and the 22nd coupling capacitor C22 ) In parallel.

Subsequently, the plurality of coupling capacitors, that is, the 21st coupling capacitors C21 to 27th coupling capacitor C27 connected to each other in series and in parallel, are configured to connect the FET switch as shown in FIG. 7 to the controller 40. The switch is turned on or off in accordance with the electrical signal applied from).

For example, the coupling coefficient of a filter using a broadband of two or more octaves is insufficient due to the adjustment of the 23rd, 24th, and 25th coupling capacitors C23, C24, and C25 connected in parallel to each other. The coupling coefficient of the filter is more precisely adjusted by allowing the twenty-first and twenty-second coupling capacitors C21 and C22 and the twenty-sixth and twenty-seventh coupling capacitors C26 and C27 to be adjusted by switching.

An electronic switch, that is, a pin diode switch or a FET switch, connected in series and parallel to the coupling circuit is not limited as shown in FIGS. 3, 4, and 5 and may be added or subtracted according to the characteristics of the digital hopping filter. .

The controller 40 compares / analyzes the filter tuning data input by the user using an input means (not shown), and outputs an on / off control signal to the first and second tuning signals to tune the filter to a desired frequency band. Output to the furnace (10, 20) and the coupling circuit (30).

Referring to the operation of the digital hopping filter of the present invention made as described above are as follows.

First, since the actual communication device uses a wide band frequency, the user inputs the filter tuning data using the input means to move the center frequency of the filter when the frequency of the channel is changed.

At this time, the control unit 40 compares / analyzes the input filter tuning data with data stored in a storage device (not shown) and transmits an electrical signal for moving the center frequency of the filter to the first and second tuning circuits 10. , 20).

The first and second tuning circuits 10 and 20 transmit electrical signals output from the controller 40 to the first and second resonant circuits 13 of the first and second tuning circuits 10 and 20. , And the first and second resonant circuits 13 and 23 turn on / off the pin diode switches configured therein according to an electrical signal applied from the controller 40.

For example, as shown in FIG. 3, if ten pin diode switches are configured in the first and second resonant circuits 13 and 23, respectively, the electrical signals output from the controller 40 may be connected to the combination of the pin diode switches. This results in a number of 1,024 cases.

In this case, when the pin diode switch is turned on according to an electrical signal applied from the controller 40, the resonant capacitor connected to the pin diode switch is resonated at a specific frequency corresponding thereto, and when the pin diode switch is turned off, the resonance capacitor is turned off. Is open and resonates at different frequencies.

For example, when two or more pin diode switches are turned on, a resonant capacitor 'on' of the pin diode switches of the first resonant circuit 13 and the second resonant circuit 23, the electrical element of the coupling circuit, and the first Resonance at a specific frequency is caused by the combined impedance of the matching circuit 11 and the second matching circuit 21.

Therefore, the digital hopping filter of the present invention can relatively shift the center frequency by combining the resonant capacitors by turning on / off the pin diode by an electrical signal applied to the controller 40.

However, when only the resonant capacitor is selected and the center frequency of the filter is moved, the characteristic deviation in the low frequency band and the high frequency band becomes large due to the change in the coupling coefficient according to the frequency change. In order to uniformly adjust characteristics such as 3dB bandwidth and insertion loss within the frequency range of use, the corresponding electrical signal is output to the coupling circuit 30.

In this case, the coupling circuit 30 turns on / off the plurality of pin diode switches SW21, SW22, and SW23 configured therein according to the signal applied from the controller 40 to change the coupling coefficient.

For example, when three pin diode switches are configured in the coupling circuit 30, the electrical signals output from the control unit 40 are eight cases by the combination of the pin diode switches SW21, SW22, and SW23. Will occur.

Therefore, since the coupling coefficient of the coupling circuit 30 can be varied by the combination of the pin diode switches, characteristics such as bandwidth and insertion loss can be uniformly adjusted according to the shift of the center frequency of the filter.

As described above, the present invention reduces the characteristic deviation in the low frequency band and the high frequency band by switching the elements of the coupling circuit and the coupling circuit connecting the tuning circuit so that the coupling coefficient of the coupling circuit can be easily adjusted according to the frequency. It provides a digital hopping filter with uniform characteristics and improves the productivity of the digital hopping filter.

Claims (6)

It consists of a matching circuit and a resonant circuit. Two tuning circuits that electronically pass a specific frequency whenever the frequency band of the used channel is changed. In the digital hopping filter, Two coupling capacitors are connected in series so that three coupling capacitors are interconnected in a T-shape, and another coupling capacitor is connected in parallel between them, and another coupling capacitor is connected to the parallel coupling capacitor connected in parallel. The digital hopping is characterized in that the coupling circuit for connecting the first tuning circuit and the second tuning circuit in a T-shape by connecting an electronic switch to each of the coupling capacitors connected in parallel and connected in parallel. filter. The electronic switch of claim 1, wherein the electronic switch of the coupling circuit connects the first pin diode and the second pin diode in series with each other, and connects the first resistor and the second resistor in parallel across the two pin diodes, respectively. One side of the third resistor is connected to the anode side of the first pin diode, one side of the fourth resistor is connected to the cathode side of the second pin diode, and the 28th capacitor and the first side of the first and second resistor are connected. A pin configured to connect one side of a 29 capacitor, the other side of the 28th capacitor and the 29th capacitor to ground, the other side of the third resistor to a reference voltage, and the other side of the fourth resistor to the controller Digital hopping filter consisting of a diode switch. The electronic switch of claim 1, wherein the electronic switch of the coupling circuit is connected to a fifth resistor having a drain of the FET connected to one side of the coupling capacitor, and a gate of the FET connected to a fifth resistor connected in series with the third inductor. The connected sixth resistor is connected to the drain side of the FET, the source side of the FET is grounded, and the thirty capacitor and the thirty first capacitor connected in series with each other are connected between the fifth resistor and the sixth resistor, A reference voltage is connected to one side of the third inductor, and one side of the fourth inductor is a digital hopping filter comprising a FET switch configured to be connected to the control unit. The electronic switch of claim 1, wherein the electronic switch of the coupling circuit is connected to a fifth resistor having a collector of a transistor connected to one side of the coupling capacitor, and a base of the transistor connected to a third inductor in series, and in series with a fourth inductor. The sixth resistor connected is connected to the collector side of the transistor, the emitter side of the transistor is grounded, and the thirty capacitor and the thirty first capacitor connected in series with each other are connected between the fifth resistor and the sixth resistor. And a reference voltage is connected to one side of the third inductor, and one side of the fourth inductor is connected to the control unit. The coupling circuit of claim 1, wherein one or more other coupling capacitors are connected in series and parallel to both ends of the coupling capacitors connecting the first air conditioning circuit and the second air conditioning circuit in series in a coupling circuit in which a plurality of coupling capacitors are connected in series. And a digital hopping filter comprising connecting an electronic switch to each of the coupling capacitors connected in series and parallel. The method of claim 1, wherein the three coupling capacitors interconnected in a T-shape are converted into a? -Shape for connecting two coupling capacitors in parallel to one coupling capacitor, and connected in parallel. One or more other coupling capacitors are respectively connected in parallel to two coupling capacitors, and each of the coupling capacitors comprises a coupling circuit converting the T-shaped coupling capacitors into a Π-shape so as to connect an electronic switch to each of the coupling capacitors. Digital hopping filter.