JP4939996B2 - Semiconductor integrated circuit device - Google Patents

Description

  The present invention relates to a technique for generating a voltage to be supplied to a power amplifier, and more particularly to a technique effective for generating an optimum voltage according to the voltage level of a battery.

  In a cellular phone, one of the important issues is how to reduce the efficiency and current consumption and maintain or extend the battery life in response to the increase in current consumption due to multifunctionalization. As a countermeasure, for example, a power management technique is known in which a DC-DC converter is used for an RF power amplifier provided in a transmission stage, and its power supply voltage is varied according to transmission power.

  By applying this, it is known that an efficient transmission system can be realized, and there are a wide variety of step-down DC-DC converters for RF power amplifiers in CDMA and W-CDMA (Wideband Code Division Multiple Access) systems. It has been put into practical use.

  However, the present inventors have found that the voltage supply technique using the step-down DC-DC converter as described above has the following problems.

  In recent years, with the demand for longer battery life, the specification of the battery is also changing to a higher density energy charging type in the near future, and the voltage characteristics of the battery can be charged to a lower voltage than the conventional battery. It is assumed that it will be used without

  In that case, the step-down DC-DC converter cannot supply a sufficient voltage to the RF power amplifier, which may cause a communication failure.

  As a technique for overcoming the above problems, it is conceivable to use a step-up / step-down type DC-DC converter.

  For example, in the case of an RF power amplifier, a step-up / step-down power supply for supplying this voltage is provided under the condition that the withstand voltage is only about 5V and the power supply voltage applied thereto is made variable under the withstand voltage. However, the concept of the protection circuit is somewhat different.

  Under any conditions, it is necessary to avoid outputting a voltage exceeding the rating, but suddenly turning off the power during communication is a problem, so even if there is an abnormality, the power supply is not simply shut down to some extent. It is considered necessary to keep it functional.

  An object of the present invention is to establish a stable communication in a mobile communication device such as a mobile phone by supplying a voltage that maintains a voltage within a rating of a high-frequency power amplifier without being affected by a remaining battery level. It is to provide technology that can be used.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  The present invention is based on a voltage adjustment signal for adjusting an output voltage, and outputs a voltage by raising or lowering a power supply voltage supplied from a battery and supplying the voltage to a power amplifier that amplifies a transmission signal A semiconductor integrated circuit device including a generation unit, wherein the power generation unit generates a voltage that is within a rating of a power amplifier when a power supply voltage supplied from a battery falls below an arbitrary voltage level. And a voltage maintaining control unit that prevents the output voltage higher than the withstand voltage of the power amplifier from being output from the power generation unit when the voltage of the voltage adjustment signal exceeds an arbitrary voltage level. It is equipped with.

  Moreover, the outline | summary of the other invention of this application is shown briefly.

  In the present invention, the power generation unit is a step-up / step-down DC-DC converter.

  Further, according to the present invention, the voltage maintenance control unit includes a first control unit that outputs a first control signal when the power supply voltage supplied from the battery is equal to or lower than an arbitrary voltage level. A first voltage switching unit that outputs a first control voltage as a voltage adjustment voltage to an error amplifier that constitutes the DC-DC converter when receiving the first control signal output from the control unit When the voltage of the voltage adjustment signal exceeds an arbitrary voltage level, the overvoltage output prevention unit is output from the second control unit that outputs the second control signal and the second control unit. When the second control signal is received, it comprises a second voltage switching section that outputs the second control voltage as a voltage adjustment voltage to the error amplifier constituting the DC-DC converter.

  Further, according to the present invention, the first control unit includes a first comparator that compares a voltage level between the first control signal and a power supply voltage supplied from the battery, and outputs the comparison result. The first voltage switching unit switches the voltage adjustment signal or the first control signal based on the comparison result output from the first comparator and outputs the voltage adjustment voltage to the error amplifier as the voltage adjustment voltage. A switch unit, and the second control unit includes a second comparator that compares the voltage adjustment signal with the second control signal and outputs the comparison result, and the second voltage switching unit includes And a second switch unit that switches the voltage adjustment signal or the second control signal based on the comparison result output from the second comparator and outputs the voltage adjustment voltage to the error amplifier as a voltage adjustment voltage. .

  According to the present invention, the power generation unit is used in a communication system in which at least one of W-CDMA, GSM (Global System for Mobile Communications), PCS (Personal Communications Service), and DCS (Digital Cellular System) is used. A voltage is supplied to a power amplifier that amplifies the band transmission signal.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  (1) The occurrence of runaway or frequent shutdown in a mobile communication device such as a mobile phone due to the remaining battery level can be reduced.

  (2) According to the above (1), it is possible to improve the reliability of the call quality while realizing a long battery life.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

  1 is a block diagram showing a configuration example of a mobile phone according to an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration example of a DC-DC converter provided in the mobile phone of FIG. 1, and FIG. FIG. 4 is an explanatory diagram schematically showing functions of an overvoltage output prevention unit and a shutdown prevention unit provided in the DC-DC converter of FIG. 2, and FIG. 4 shows an example of input / output characteristics in the DC-DC converter of FIG. FIG. 5 and FIG. 5 are diagrams showing characteristic examples of the power supply voltage and the output voltage in the DC-DC converter of FIG.

  In the present embodiment, as shown in FIG. 1, a mobile phone 1 that is one of mobile communication devices includes an antenna switch 2, a power amplifier 3, a SAW (Surface Acoustic Wave) filter 4, an RF processing unit 5, and a DC- A DC converter 6, a baseband unit 7, an application processor 8, and a memory 9 are provided.

  The antenna switch 2 switches a signal to be transmitted / received based on a control signal from the baseband unit 7. The power amplifier 3 amplifies the W-CDMA transmission signal that is output from the RF processing unit 5 and uses, for example, the 2.1 GHz band.

  The SAW filter 4 selects a signal having a specific frequency (2.1 GHz band) from the received signal. The RF processing unit 5 demodulates the reception signal and modulates the transmission signal. The RF processing unit 5 includes a D / A (Digital / Analog) converter (DAC) 5a. The D / A converter 5 a performs D / A conversion on the control signal output from the baseband unit 7 serving as a power generation unit, and generates a signal IN for controlling the DC-DC converter 6.

  The DC-DC converter 6 generates a power supply voltage to be supplied to the power amplifier 3. This DC-DC converter 6 is a step-up / step-down type DC-DC converter, and can generate a voltage higher than the battery voltage.

  The baseband unit 7 converts transmission data into an I signal or a Q signal, outputs a control signal, and controls the RF processing unit 5. The application processor 8 executes a high-level OS (Operating System) and manages application control.

  The memory 9 includes, for example, a nonvolatile semiconductor memory exemplified by a flash memory, an SRAM (Static Random Access Memory), and an SDRAM (Synchronous Dynamic RAM).

  FIG. 2 is a block diagram illustrating a configuration example of the DC-DC converter 6.

  As shown, the DC-DC converter 6 includes a step-down driver 10, a step-up driver 11, transistors 12 to 14, a diode 15, a reference power supply generation unit 16, a step-down PWM signal generation unit 17, a step-up PWM signal generation unit 18, An error amplifier 19, an overvoltage output prevention unit 20, a shutdown prevention unit 21, an error amplifier reference voltage generation unit 22, a UVLO (UnderVoltage LockOut) 23, and the like are provided.

  For example, one connection portion of the transistor 12 formed of a P-channel MOSFET (Metal Oxide Semiconductor Field Effect Transistor: hereinafter referred to as MOS), the step-down driver 10, and the reference power generation unit 16 receive the power supply voltage VCC from the battery B. Each is connected to be supplied.

  For example, one connection portion of a transistor 13 made of an N-channel MOS is connected to the other connection portion of the transistor 12, and a reference potential VSS is connected to the other connection portion of the transistor 13. . The gates of the transistors 12 and 13 are connected so that a driving signal output from the step-down driver 10 is input thereto.

  Further, for example, one connection portion of the transistor 14 made of an N-channel MOS and the anode of the diode 15 are connected to the connection portion between the transistor 12 and the transistor 13 via an externally connected coil L. Yes.

  A reference potential VSS is connected to the other connection portion of the transistor 14, and a driving signal output from the boost driver 11 is connected to the gate of the transistor 14.

  The booster driver 11 is connected so that the power supply voltage is supplied via the cathode of the diode 15, and the cathode of the diode 15 becomes the output section of the DC-DC converter 6.

  A step-down PWM signal generation unit 17 is connected to the input unit of the step-down driver 10. The step-down driver 10 drives the transistors 12 and 13 based on a PWM (Pulse Width Modulation) signal generated by the step-down PWM signal generation unit 17.

  A boosting PWM signal generation unit 18 is connected to an input unit of the boosting driver 11. The step-up driver 11 drives the transistor 14 based on the PWM signal generated by the step-up PWM signal generation unit 18.

  The reference voltage generated by the error amplifier reference voltage generator 22 is input to one input portion of the error amplifier 19, and the D / A converter 5a (FIG. 1) is input to the other input portion of the error amplifier 19. Is connected so that a voltage adjusting signal output from the terminal is input.

  The error amplifier 19 compares the reference voltage generated by the error amplifier reference voltage generation unit 22 with the voltage adjustment signal output from the D / A converter 5a (FIG. 1), amplifies the error, and outputs the amplified error. . The error amplifier reference voltage generation unit 22 divides the output voltage of the DC-DC converter 6 by the resistors R1 and R2, and outputs the divided voltage as an error amplifier reference voltage.

  The step-down PWM signal generation unit 17 and the step-up PWM signal generation unit 18 each generate a PWM signal corresponding to the output signal output from the error amplifier 19.

  The overvoltage output prevention unit 20 prevents the output voltage of the DC-DC converter 6 from exceeding an arbitrary voltage level.

  When the voltage level of the power supply voltage VCC in the battery B decreases, the shutdown prevention unit 21 serving as a voltage maintenance control unit supplies a voltage corresponding to the decrease in the voltage level to the power amplifier 3 to prevent output runaway or shutdown. To prevent.

  The overvoltage output prevention unit 20 includes a comparator (second comparison unit) 20a serving as a second control unit, and a switch (second switch unit) 20b serving as a second voltage switching unit.

  The shutdown prevention unit 21 includes a comparator (first comparison unit) 21a serving as a first control unit, and a switch (first switch unit) 21b serving as a first voltage switching unit.

  One input part of the comparator 21a is connected so that the reference voltage VREF2 generated by the standard power supply generation part 16 is input. One input part of the comparator 21a is one input of the switch 21b. Connected to the department. The reference voltage VREF2 generated by the reference power supply generation unit 16 is a power supply voltage that depends on the power supply voltage VCC.

  The other input section of the comparator 21a is connected so that a voltage adjustment signal output from the D / A converter 5a is input. Further, the voltage adjustment signal of the D / A converter 5a is connected to be input to the other input section of the switch 21b.

  The other input section of the comparator 20a and the other input section of the switch 20b are connected to the output section of the switch 21b. The reference voltage VREF1 generated by the standard power supply generation unit 16 is connected to one input unit of the comparator 20a and one input unit of the switch 20b, respectively.

  The control unit of the switch 21b is connected to the output unit of the comparator 21a, and the control unit of the switch 20b is connected to the output unit of the comparator 20a. The switch 21b selects either the reference voltage VREF2 or the voltage adjustment signal output from the D / A converter 5a based on the comparison result (first control signal) of the comparator 21a, and the voltage adjustment voltage Output as a signal.

  The switch 20b is based on the comparison result (second control signal) of the comparator 20a, the reference voltage VREF1 generated by the reference power supply generator 16, or the voltage of the D / A converter 5a output via the switch 21b. One of the adjustment signals is selected and output as a voltage adjustment voltage Vadj. When the UVLO 23 receives the shutdown signal SD output from the RF processing unit 5, the UVLO 23 stops the operation of the reference power generation unit 16.

  Next, operations of the overvoltage output prevention unit 20 and the shutdown prevention unit 21 in the present embodiment will be described.

  FIG. 3 is an explanatory diagram schematically showing the functions of the overvoltage output prevention unit 20 and the shutdown prevention unit 21.

  As shown in the figure, the error amplifier 19 includes transistors Q1 to Q7, a capacitance element C, and a resistor R. One of connection portions of the transistors Q1 and Q6 is connected so that the power supply voltage VCC of the battery B is supplied. The transistors Q2 and Q3 and the transistors Q4 and Q5 connected in series are connected between the other connection portion of the transistor Q1 and the reference potential VSS, thereby forming a differential amplifier.

  A reference voltage generated by the error amplifier reference voltage generation unit 22 is connected to the gate of the transistor Q2, and an overvoltage output prevention unit 20 and a shutdown prevention unit 21 are connected to the gate of the transistor Q4. The voltage adjustment voltage Vadj that is output via the connection is input.

  The gates of the transistors Q1 and Q6 are connected so that the reference voltage VREF2 generated by the standard power supply generation unit 16 is input thereto. The other connection portion of the transistor Q2 is connected to the gate of the transistor Q3, and the other connection portion of the transistor Q4 is connected to the gate of the transistor Q5.

  Further, one connection portion of the transistor Q7 is connected to the other connection portion of the transistor Q6, and the reference potential VSS is connected to the other connection portion of the transistor Q7.

  A capacitance element C and a resistor R connected in series are connected between one connection portion of the transistor Q7 and the gate, and a connection portion between the transistor Q6 and the transistor Q7 is an output portion of the error amplifier 19. It becomes.

  As described above, the switch 21b that performs switching based on the output signal of the comparator 21a is output to one input unit (FIG. 3, terminal B2) via, for example, the transistor Qv of the reference power generation unit 16. The reference voltage VREF2 is connected to be supplied. The other input part (FIG. 3, terminal A2) of the switch 21b is connected so that the voltage adjustment signal output from the D / A converter 5a is input.

  Further, as described above, the switch 20b that performs switching based on the output signal of the comparator 20a has, for example, a reference voltage generated from the reference power supply generation unit 16 at one input unit (FIG. 3, terminal B1). VREF1 is connected so as to be supplied, and the other input part (FIG. 3, terminal A1) of the switch 20b is connected so that a signal output from the switch 21b is input. The signal output from the switch 20b is supplied to the gate of the transistor Q4 as the voltage adjustment voltage Vadj.

  Here, it is assumed that the operating voltage range of the battery B is, for example, about 2.3V to about 4.7V. Reference voltage VREF1 is about 1.57 V, for example, and reference voltage VREF2 is about (power supply voltage VCC−threshold voltage Vth (transistor Qv)) V. Further, the DC-DC converter 6 outputs, for example, a voltage about three times the voltage adjustment voltage Vadj.

  First, the comparator 21a compares the voltage level of the voltage adjustment signal output from the D / A converter 5a with the reference voltage VREF2, and if the voltage level of the voltage adjustment signal is lower than the reference voltage VREF2. Since it is within the operating voltage range of the battery B, a control signal is output so that the switch 21b is connected to the terminal A2.

  Subsequently, the comparator 20a compares the voltage level of the voltage adjustment signal output via the switch 21b with the reference voltage VREF1, and if the voltage level of the voltage adjustment signal is lower than the reference voltage VREF1, it is within the rating. It is determined that the voltage is input, and a control signal is output so that the switch 20b is connected to the terminal A1 side. As a result, the voltage adjustment signal output from the D / A converter 5a is input to the error amplifier 19 as the voltage adjustment voltage Vadj.

  Further, when the voltage level of the voltage adjustment signal becomes equal to or higher than the reference voltage VREF2 due to the decrease in the voltage level of the power supply voltage VCC, the comparator 21a controls the control signal so that the switch 21b is connected to the terminal B2 side. And the reference voltage VREF2 is input to the error amplifier 19 as the voltage adjustment voltage Vadj.

  In this case, if the power supply voltage VCC of the battery B is about 2.4V, for example, the reference voltage VREF2 is about (2.4V−0.9V) = 1.5V, and about 1.5V is the voltage. The adjustment voltage Vadj is input to the error amplifier 19.

  As described above, since the DC-DC converter 6 outputs a voltage about three times the voltage adjustment voltage Vadj, the output voltage of the DC-DC converter 6 is about 4.5V. As a result, the error amplifier 19 can be clamped at the upper limit of the operating voltage, and the mobile phone 1 can be prevented from being shut down or runaway.

  On the other hand, when the voltage adjustment signal output through the switch 21b becomes an unrated voltage level, the voltage level of the voltage adjustment signal becomes equal to or higher than the reference voltage VREF1, and the comparator 20a has the switch 20b connected to the terminal. A control signal is output so as to be connected to the B1 side.

  As a result, the reference voltage VREF1 is input to the error amplifier 19 as the voltage adjustment voltage Vadj. In this case, if the reference voltage VREF1 is about 1.57V as described above, the output voltage of the DC-DC converter 6 is about 4.7V, and even if the voltage level of the voltage adjustment signal is significantly increased. An increase in the output voltage of the DC-DC converter 6 can be suppressed, and the mobile phone 1 can be prevented from runaway or element destruction.

  FIG. 4 is a graph showing an example of input / output characteristics of the DC-DC converter 6, and FIG. 5 is a graph showing an example of characteristics of the power supply voltage and the output voltage in the DC-DC converter 6.

  In FIG. 4, the horizontal axis indicates the voltage level of the voltage Vc of the voltage adjustment signal output from the D / A converter 5a, and the vertical axis indicates the output voltage of the DC-DC converter 6. In FIG. 5, the horizontal axis indicates the voltage level of the power supply voltage VCC supplied by the battery B, and the vertical axis indicates the output voltage of the DC-DC converter 6.

  As shown in these drawings, by providing the overvoltage output prevention unit 20, the output voltage of the DC-DC converter 6 becomes higher than the power supply voltage VCC (voltage higher than the element withstand voltage of the power amplifier 3) to prevent overvoltage. can do.

  Further, by providing the shutdown prevention unit 21, even if the power supply voltage VCC of the battery B is lowered to the power amplifier 3, it is possible to supply a voltage that depends on (depends on) the power supply voltage VCC. Even when the voltage VCC is lower than about 2.5 V, shutdown or the like can be eliminated, and the operating voltage range of the battery B can be increased.

  Thereby, according to this Embodiment, the battery life in the mobile telephone 1 at the time of a telephone call can be lengthened, improving the reliability of the mobile telephone 1. FIG.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say.

  In the above-described embodiment, the configuration in which the power amplifier for amplifying the W-CDMA transmission signal using the 2.1 GHz band is provided. However, as shown in FIG. 6, the signal for the W-CDMA system is amplified. In addition to the power amplifier 3 to be provided, for example, a plurality of power amplifiers such as a power amplifier 3a for amplifying a GSM signal using the 900 MHz band are provided, and the output voltage of the DC-DC converter 6 is supplied to the power amplifiers 3 and 3a, respectively. It may be configured to supply.

  In the above-described embodiment, the cellular phone has the antenna switch 2 (FIG. 1) and the power amplifier 3 (FIG. 1) as separate modules. For example, as shown in FIG. The switch 2 and the power amplifier 3 may be configured as one high frequency power amplification module Md.

  Furthermore, not only the antenna switch 2 and the power amplifier 3, but also one high frequency power amplification module including a DC-DC converter 6 to which the present invention for supplying a voltage to the power amplifier 3 is applied as shown in FIG. You may make it comprise as Md.

  INDUSTRIAL APPLICABILITY The present invention is suitable for technology for extending the battery life and improving communication performance in mobile phones.

It is a block diagram which shows the structural example of the mobile telephone by one embodiment of this invention. It is a block diagram which shows the structural example of the DC-DC converter provided in the mobile telephone of FIG. It is explanatory drawing which showed typically the function of the overvoltage output prevention part provided in the DC-DC converter of FIG. 2, and a shutdown prevention part. It is a figure which shows the input-output characteristic example in the DC-DC converter of FIG. It is a figure which shows the example of a characteristic of the power supply voltage and output voltage in the DC-DC converter of FIG. It is a block diagram which shows the structural example of the mobile telephone by other embodiment of this invention. It is a block diagram which shows an example of a structure in the mobile telephone by other embodiment of this invention. It is a block diagram which shows the other example of the structure in the mobile telephone by other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cellular phone 2 Antenna switch 3 Power amplifier 3a Power amplifier 4 SAW filter 5 RF processing part 5a D / A converter 6 DC-DC converter 7 Baseband part 8 Application processor 9 Memory 10 Buck driver 11 Boost driver 12-14 Transistor 15 Diode 16 Reference power supply generation unit 17 Step-down PWM signal generation unit 18 Step-up PWM signal generation unit 19 Error amplifier 20 Overvoltage output prevention unit 20a Comparator 20b Switch 21 Shutdown prevention unit 21a Comparator 21b Switch 22 Error amplifier reference voltage generation unit 23 UVLO
B Battery Q1-Q7 Transistor Qv Transistor C Capacitance element R Resistance Md High frequency power amplification module

Claims (7)

Based on the voltage adjustment signal for adjusting the output voltage, boosting the power supply voltage supplied from a battery, or down to output a voltage, the voltage, the power generation unit supplies to the power amplifier for amplifying a transmission signal Have
The power generation unit
A reference power generation unit;
A first comparator for comparing the first reference voltage supplied from the reference power generation unit and the voltage adjustment signal; and a first switch circuit to which the first reference voltage and the voltage adjustment signal are connected. And the first switch circuit selects either the first reference voltage or the voltage adjustment signal based on the comparison result of the first comparator, and outputs the voltage adjustment signal as a voltage adjustment signal. When,
A second comparator for comparing the second reference voltage supplied from the reference power generation unit and the voltage adjustment signal; a second switch circuit to which the second reference voltage and the voltage adjustment signal are connected; And the second switch circuit selects either the second reference voltage or the voltage adjustment signal based on the comparison result of the second comparator and outputs it as a voltage adjustment signal. When,
A reference voltage generation unit that divides the output voltage of the power supply generation unit by resistance and generates a reference voltage for an error amplifier;
An error amplifier that inputs the voltage adjustment signal supplied via the first switch circuit and the second switch circuit and the reference voltage, amplifies the error, and outputs the error.
When the first comparator detects that the voltage level of the voltage adjustment signal is equal to or higher than the first reference voltage, the first switch circuit sets the first reference voltage to the voltage maintenance control unit. Output as a voltage adjustment signal,
When the second comparator detects that the voltage level of the voltage adjustment signal from the voltage maintenance control unit is equal to or higher than the second reference voltage, the overvoltage output prevention unit detects the second switch circuit Outputting a second reference voltage to the error amplifier as the voltage adjustment signal;
The power generation unit, the semi-conductor integrated circuit device for outputting a voltage based on the output of the error amplifier. The semiconductor integrated circuit device according to claim 1.
The power generation unit
Buck-boost DC-DC converter ing from semiconductors integrated circuit device. The semiconductor integrated circuit device according to claim 2.
The power generation unit further includes:
A PWM circuit supplied with the output of the error amplifier;
A driver circuit supplied with an output signal of the PWM circuit,
The driver circuit is a semiconductor integrated circuit device that generates a voltage by driving a transistor in accordance with an output signal of the PWM circuit. The semiconductor integrated circuit device according to claim 3.
When the first comparator detects that the voltage level of the voltage adjustment signal is lower than the first reference voltage, the first switch circuit selects the voltage adjustment signal. Semiconductor integrated circuit device that outputs The semiconductor integrated circuit device according to claim 4.
When the second comparator detects that the voltage level of the voltage adjustment signal from the voltage maintenance control unit is lower than the second reference voltage, the overvoltage output prevention unit detects the second switch circuit A semiconductor integrated circuit device for selecting a voltage adjustment signal from a voltage maintenance control unit and outputting the selected signal to the error amplifier. The semiconductor integrated circuit device according to claim 5.
The first reference voltage is a voltage obtained by subtracting a threshold voltage of a transistor from the power supply voltage,
The semiconductor integrated circuit device, wherein the second reference voltage is lower than the first reference voltage. The semiconductor integrated circuit device according to any one of claims 1 to 6 ,
The power generation unit
W-CDMA, GSM, PCS or semi conductor integrated circuit device you voltage supplied to said power amplifier for amplifying a transmission signal of a frequency band used for at least one of the communication methods of DCS,.

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