KR100344620B1 - Dual mode diode switch - Google Patents

Abstract

The dual mode diode switch of the present invention prevents interference between signals at both ends by one bias circuit connected to the GSM stage and the DCS1800 stage, and forms at least one notch in the bias circuit or has a bandwidth of about 900 to 1800 MHz. Phosphor blocking filter is formed.

Description

Dual Mode Diode Switch {DUAL MODE DIODE SWITCH}

The present invention relates to a dual-mode diode switch used in a communication system such as a dual-band mobile phone that can transmit and receive signals through two different bands, and in particular, by forming a bias circuit of the two communication terminals as a single circuit configuration and driving logic The present invention relates to a dual mode diode switch that can reduce manufacturing costs by simplifying the operation.

Recently, with the development of wireless communication technology, mobile communication equipment is rapidly spreading. However, such mobile communication equipment (ie, mobile phones) is composed of different communication methods according to regions. For example, the Global System for Mobil Communication (GSM) method is mainly used in Europe, and the DCM 1800 (Digital Communication System) method is mainly used in North America or Asia. GSM is generally used in the 900MHz frequency band and DCM1800 is used in the 1800MHz frequency band. Therefore, although a different communication system must be used in a different communication method, a multi-communication system that can be commonly used even in a different call method has been developed.

In order to use such a multi-communication system, a dual mode diode switch in which two diode switches are formed to pass only a frequency band of a signal received or transmitted in each communication method (ie, a frequency band) is required.

1 is a view showing a conventional dual mode diode switch. As shown in the figure, the general dual-mode diode switch DCS1800 to realize the DCS1800 communication with the GSM terminal diode switching unit (3) for realizing GSM communication based on the diplexer (1) connected to the antenna terminal However, the diode switching unit 10 is provided. The diode switching unit 3 of the GSM stage is connected to a first λ / 4 transmission line 7 corresponding to a quarter length of the GSM communication wavelength to a receiving terminal Rx, and a first low pass filter to the transmitting terminal Tx. (5) is connected. In addition, a first diode 8 is provided in the first low pass filter 5 and the first λ / 4 transmission line 7, and between the receiving end Rx and the first λ / 4 transmission line 7. Two diodes 9 are installed and connected to earth. One end of the diplexer 1 is connected between the first diode 8 and the first? / 4 transmission line 7. In addition, a first bias voltage is applied between the first low pass filter 5 and the first diode 8 to control the GSM stage diode switching unit 3.

The DCS1800 stage diode switching unit 10 also has the same configuration as the GSM stage diode switch 3. That is, a second λ / 4 transmission line 14 corresponding to a quarter length of the DCS1800 communication band wavelength is connected to the receiving terminal Rx, and a second low pass filter 12 is connected to the transmitting terminal Tx. . In addition, a third diode 15 is provided between the second low pass filter 12 and the second λ / 4 transmission line 14, and between the second λ / 4 transmission line 14 and the receiving end Rx. The fourth diode 16 is installed in it is connected to the ground. The third diode 15 and the second λ / 4 transmission line 14 are connected to the other select terminal of the diplexer 1 and between the second low pass filter 12 and the third diode 15. The second bias voltage is applied to the DCS1800 stage diode switching unit 10 to control the DCS1800 stage.

The first bias voltage and the second bias voltage are respectively applied by a bias circuit external to the diode switching unit, and such a bias circuit is illustrated in FIG. 2. In the figure, reference numeral R denotes the amount of current supplied to the circuit as a resistor, and L denotes an RF choke coil that passes only a direct current and blocks a signal. In addition, C is a bypass capacitance, which allows the RF signal to pass to ground without transmitting to the bypass circuit. In other words, resistor R determines the DC bias and L and C do not allow the bias circuit to affect the RF signal of the circuit. Normally, the C value is seen as a short with respect to the operating frequency of the circuit and the L value is seen as an open.

When the bias circuit of the above configuration is applied to the dual mode diode switch, a bias voltage is applied through each bias circuit to control the GSM stage diode switching unit 3 and the DCS1800 stage diode switching unit 10 as shown in Table 1. do.

First bias circuit Second bias circuit GSM Tx on off Rx off off DCS1800 Tx off on Rx off off

In this case, On represents a state in which a voltage of about 2 to 3 V is applied, and Off represents a voltage of approximately 0 V.

As shown in Table 1, when the first bias voltage of the GSM stage diode switching unit 3 is applied (that is, when the first bias voltage is turned on or off), the DCS1800 stage diode switching unit 10 is always turned off. On the contrary, when the second bias voltage of the DCS1800 stage diode switching unit 10 is applied, the first bias voltage of the GSM stage diode switching unit 3 is always in the OFF state. Therefore, when the dual mode diode switch is used in a mobile phone or the like, the second bias voltage of the DCS1800 stage diode switching unit 10 is always in the OFF state in the region where the GSM communication method is applied, and in the region where the DCS1800 conventional method is applied. The GSM stage diode switching unit 3 is always in an off state, so that it is always possible to maintain a call state even while moving to another area of a communication method.

However, in the dual-mode diode switch of the above-described configuration, in order to apply the bias voltages for controlling the GSM stage diode switching unit 3 and the DCS1800 stage diode switching unit 10, two bias circuits must be formed. This has become complicated, so there has been an increase in the number of logics that operate.

The present invention is to solve the above problems, to provide a dual-mode diode switch that can prevent the signal interference between both ends by forming a bias circuit formed with a low pass filter between the GSM stage and the DCS1800 stage. For the purpose of

In order to achieve the above object, the dual mode diode switch of the present invention is a dual mode diode switch for selectively transmitting and receiving signals of different first and second bands, the first transmission line connected to the receiving terminal, connected to the transmitting terminal A first band pass filter configured to filter a signal and a first diode disposed between the first transmission line and the first band pass filter to transmit and receive a signal of a first band; A second transmission line connected to the receiving terminal, a second band pass filter connected to the transmission terminal for filtering the signal, and a second diode provided between the second transmission line and the second band pass filter to transmit and receive the signal of the second band A second communication area; A diplexer for selectively transmitting and receiving signals of a first band or a second band by selectively connecting an antenna terminal to the first communication area and the second communication area, a first diode of the first communication area and the second communication; A bias having a low pass filter which simultaneously applies a bias voltage for on / off switching control to the second diode of the region and forms at least one notch to prevent signal interference between the first and second communication regions. It consists of a circuit.

The bias circuit is composed of a low pass filter composed of capacitance and inductance. When one resonator composed of capacitance and inductance is formed, the bias circuit forms a notch at a frequency of about 1800 MHz and includes a plurality of series resonators and parallel resonators. A stopband is formed between about 900Mz and about 1800MHz.

1 is a view showing a conventional dual mode diode switch.

FIG. 2 is a diagram illustrating a bias circuit of the dual mode diode switch shown in FIG. 1. FIG.

3 illustrates a dual mode diode switch according to an embodiment of the present invention.

4 illustrates a bias circuit of a dual mode diode switch according to another embodiment of the present invention.

5 is a graph showing the frequency response characteristics in each mode of the bias circuit of the dual mode diode switch according to the present invention.

-Brief description of the symbols for the main parts of the drawing.

101: diplexer 103: GSM stage 110: DCS1800 stage 125: bias circuit

Hereinafter, a dual mode diode switch according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a diagram illustrating a dual mode diode switch according to an embodiment of the present invention. In the dual mode diode switch of the present invention, a bias voltage is commonly applied by using one bias circuit to prevent a GSM stage diode switch and a DCS1800 stage diode. Control all switches.

As shown in the figure, the GSM stage diode switching unit 103 includes a first λ / 4 transmission line 107 connected to the receiving end Rx and a first low pass filtering the signal connected to the transmitting end Tx. A first diode 108 provided between the pass filter 105, the first? / 4 transmission line 107 and the first low pass filter 105, and the first? / 4 transmission line 107; The second diode 109 is installed between the receiving terminals Rx and connected to the ground.

In addition, the DCM1800 stage diode switching unit 110 also has the same configuration as the GSM stage diode switching unit 103 described above. That is, the DCM1800 stage diode switching unit 110 is a second λ / 4 transmission line 114 connected to the receiving end (Rx), and the second low pass filter 112 for filtering a signal connected to the transmitting end (Tx) and transmitted. ), A second diode 115 provided between the second λ / 4 transmission line 114 and the second low pass filter 112, the second λ / 4 transmission line 114 and the receiving end Rx. It is composed of a fourth diode 116 installed between and connected to the ground.

Further, the first low pass filter 105 and the first diode 108 of the GSM stage diode switching unit 103 and the second low pass filter 112 and the third diode of the DCM1800 stage diode switching unit 110. A bias circuit 125 for applying a bias voltage is connected between the 115 lines.

The operating mode of the dual mode diode switch of the above configuration is shown in Table 2.

Bias voltage mode On GSM-Tx, DCS1800-Tx off GSM-Rx, DCS1800-Rx

As shown in the above table, when the bias voltage is turned on, both the GSM stage diode switching unit 103 and the DCS1800 stage diode switching unit 110 are in a transmission mode, and when turned off, the GSM stage diode switching unit 103 is turned off. ) And the DCS1800 stage diode switching unit 110 are both in the reception mode. That is, as the bias voltage is turned on and off, the GSM stage diode switching unit 103 and the DCS1800 stage diode switching unit 110 operate simultaneously.

In general, the GSM stage diode switching unit 103 operates at a signal of 900MHz and the DCS1800 stage diode switching unit 110 operates at 1800MHz. In the reception mode, the GSM stage diode switching unit 103 and the DCS1800 stage diode switching unit 110 operate in different frequency bands, but no problem occurs, but a problem may occur in the transmission mode. In the transmission mode of the GSM stage diode switching unit 103, the operating frequency f0 is 900M, but the actual signal is generated not only at the operating frequency f0 but also at the first harmonic 2f0 and the second harmonic 3f0. The signal having a frequency of 1800 MHz causes interference with the DCS1800 stage diode switching unit 110.

Therefore, in order to prevent interference between the GSM stage diode switching unit 103 and the DCS1800 stage diode switching unit 110, a bias circuit 125 as shown in the drawing is connected to the first harmonic signal of the GSM transmission signal or DCS1800. It blocks the transmission signal of and separates between the two modes. As shown in the figure, the bias circuit 125 is composed of L1, L2, R and C. C and L1 correspond to the RF choke coil and bypass capacitance in the conventional bias circuit, respectively, and function as a low pass filter. Therefore, by setting the values of C and L1 and acting as a low pass filter, it is possible to attenuate the signal of the frequency to be blocked. However, since C and L1 alone cannot satisfy these stopping characteristics, L2 is added and resonated with C to form a notch at 1.8 Gz corresponding to the DCM1800 communication signal. The frequency response characteristic curve of the bias circuit of the above structure is shown in Fig. 5A.

4 (a) to 4 (d) are diagrams illustrating other embodiments of the dual mode diode switch according to the present invention. In the figure, the configuration of each GSM stage diode switch and the DCS1800 stage diode switch are the same, and only the configuration of the bias circuit is different, so the description of the configuration of the diode switch is omitted.

First, in the bias circuit of the dual mode diode switch shown in FIG. In the bias circuit shown in FIG. 3, the first harmonic f0 at the transmitter of the GSM stage and the signal at the transmitter of the DCS1800 stage can be prevented from interfering with each other. f0) is included in the passband of the low pass filter of the bias circuit to affect the DCS1800 stage through the bias line.

In the embodiment shown in Figure 4 (a) as described above, in order to prevent the operating frequency of the GSM-level transmission signal affects the DCS1800 stage, a series resonator is connected through a shunt. Accordingly, by properly adjusting the values of C1, C2, L1, and L2, not only the 1800 MHz frequency of the GSM stage but also the 900 MHz frequency can be blocked, thereby preventing the GSM stage and the DCS1800 stage from interfering with each other.

In the embodiment shown in FIG. 4 (b), C1 and L1 form a series resonator connected in series, and C2 and L2 form a parallel resonator connected in parallel. In this embodiment, similarly to the embodiment of FIG. 4 (a), the serial resonance unit and the parallel resonance unit not only interfere with the operating frequency of the GSM stage (that is, f0 of 900 MHz) but also the first harmonic of the GSM stage and the frequency of the DCS1800 stage. To prevent it.

The bias circuits shown in FIGS. 4 (a) and 4 (b) have a low pass filter structure to prevent interference between the GSM stage and the DCS1800 stage. In other words, as shown in FIG. 5 (b), the bias circuit is formed of a band stop filter in which two notches are formed at 900 MHz and 1800 MHz to prevent interference between each end of the dual mode diode switch. At this time, since it is determined by Equation 1 below, the stop band can be determined by appropriately adjusting the C and L values.

4 (c) and 4 (d) show a bias circuit in which three or more resonators are formed in FIGS. 4 (a) and 5 (b), respectively. That is, the bias circuit of FIG. 4 (c) represents a bias circuit in which three or more series resonators are formed, and the bias circuit of FIG. 4 (d) represents a bias circuit in which a plurality of series resonance units and parallel resonance units are formed. By forming three or more series resonators and a plurality of parallel resonators and series resonators, a stop band of 900 MHz to 1800 MHz is formed as shown in Fig. 5 (c), so that the operation signal of the GSM stage affects the DCS1800 stage. It can be prevented from affecting.

As described above, the present invention can form a bias circuit in which at least one notch is formed in the dual mode diode switch, thereby preventing interference between signals between the stages. In addition to the simplicity of logic, dual-mode diode switches can be manufactured that simplify the design and reduce the manufacturing cost.

Claims (7)

In the dual mode diode switch for selectively transmitting and receiving signals of different first and second bands, A first band signal comprising a first transmission line connected to a reception terminal, a first band pass filter connected to a transmission terminal to filter a signal, and a first diode provided between the first transmission line and the first band pass filter A first communication area for transmitting and receiving; A second transmission line connected to the receiving terminal, a second band pass filter connected to the transmission terminal to filter the signal, and a diode installed between the second transmission line and the second band pass filter to transmit and receive the signal of the second band A second communication area; A diplexer for selectively transmitting and receiving signals of first and second bands by selectively connecting an antenna terminal, the first communication region, and a second communication region; And At least one notch connected to a first diode of the first communication area and a second diode of the second communication area to simultaneously apply a bias voltage, and to prevent signal interference between the genital first communication area and the second communication area. Dual-mode diode switch consisting of a bias circuit having a low pass filter forming a. The dual mode diode switch of claim 1, wherein the first communication area is a GSM terminal and the second communication area is a DCS1800 terminal. delete The dual mode diode switch of claim 1, wherein the stop filter is formed of capacitance and inductance. The dual mode diode switch of claim 4, further comprising an inductance formed between the capacitance and the inductance. The dual mode diode switch of claim 1, wherein the low pass filter comprises a plurality of series resonators having a capacitor and an inductance connected in series. The dual mode diode switch of claim 6, wherein the low pass filter comprises at least one series resonator having a capacitance and an inductance connected in series, and at least one parallel resonator having a capacitance and an inductance connected in parallel.