JP4614274B2 - Mobile phone terminal - Google Patents

Description

The present invention is portable telephone terminal, in particular regarding the preferred power amplification device using its transmitting device.

  At present, mobile phone services called third generation are becoming more widespread, and services that enable higher-speed communication are being added. The issues imposed on the power amplifying apparatus used in the wireless transmission unit are increasingly being close-up, and many unprecedented performances are required.

  With the spread of new mobile phones, many application functions using high-speed communication are being commercialized. Here, transmission data from the terminal is high speed. In high-speed communication, normal code multiplexing is performed, and as a result, the peak factor increases, and adjacent distortion, that is, adjacent channel leakage power ratio (ACPR) deteriorates.

  On the other hand, high-capacity batteries are required, and alloy electrode batteries that replace conventional carbon electrode batteries are attracting attention. The difference in characteristics between the two is shown in FIG. The carbon electrode battery has a constant discharge voltage of approximately 3.5 V and is easy to use, but at present the capacity has reached the theoretical limit and is difficult to increase.

  On the other hand, in an alloy electrode battery, the capacity is expected to increase by up to 50%, which is promising, but the discharge voltage gradually decreases to about 2.7V. At present, a power amplifier (PA) used for a mobile phone terminal requires a power supply voltage of 3.5 V, so the alloy electrode battery of FIG. 5 cannot be used. When using a power amplifying device that can operate at 2.7 V, it is necessary to perform a design that satisfies the characteristics when the battery voltage is low, and the efficiency is greatly reduced when the voltage is high. Therefore, it is necessary to use a step-down DC-DC converter.

  The present invention has been made in such a background, and the object of the present invention is to achieve either a relatively high battery voltage or a relatively low battery voltage without reducing efficiency and without using a step-down DC-DC converter. Is to provide a mobile phone terminal and a power amplifying device which can be flexibly adapted.

  The present invention is a mobile phone terminal including a transmission device for transmitting a radio signal, which is operated by a battery, and a control means for controlling the operation of the transmission device, wherein the transmission device amplifies the transmission signal. The power amplifying apparatus includes an amplifier that amplifies a signal to be transmitted, and a variable impedance load circuit that switches between a first impedance and a second impedance as a load of the amplifier, and the control unit includes: The variable impedance load monitors the voltage of the battery, selects the first impedance when the battery voltage is equal to or higher than a predetermined threshold, and selects the second impedance when the battery voltage falls below the predetermined threshold. Control the circuit.

  Compared with a relatively high battery voltage without reducing efficiency and using a step-down DC-DC converter by using the variable impedance load circuit capable of switching the impedance by the control means as a load of the amplifier It is possible to flexibly cope with any low battery voltage.

  Preferably, the first impedance is an impedance that maximizes both output and efficiency at a predetermined high battery voltage level, and the second impedance is such that both output and efficiency are maximized at a predetermined low battery voltage level. Impedance.

  Even if the battery voltage is within a voltage range corresponding to the predetermined high battery voltage level, the variable impedance load circuit is switched to the second impedance when the operation mode of the transmitter is in the predetermined operation mode. May be. As a result, it is possible to change the operation condition only for a predetermined operation mode and perform a power amplification operation suitable for the operation mode.

  For example, the amplifier has a first source grounded FET that receives an input signal at the gate terminal via the first matching circuit, and a signal output to the drain terminal of the first source grounded FET in the second matching circuit. And a drain terminal of each of the first and second source grounded FETs connected to the battery via a coil or a transmission line having a predetermined length. It is.

  Another mobile phone terminal according to the present invention includes a transmitter for transmitting a radio signal selectively operating in the first operation mode and the second operation mode, and control means for controlling the operation of the transmitter. The transmission device includes a power amplification device that amplifies a transmission signal. The power amplification device includes an amplifier that amplifies a signal to be transmitted and a first impedance as a load of the amplifier. And a variable impedance load circuit for switching the second impedance, and the control means controls the variable impedance load circuit to select the first impedance or the second impedance according to the operation mode. The control means can perform a power amplification operation suitable for each operation mode by selecting the first impedance or the second impedance according to the operation mode.

  A power amplifying device according to the present invention includes an amplifier that amplifies a signal, and a variable impedance load circuit that switches a first impedance and a second impedance as a load of the amplifier, and the first impedance is at a predetermined high battery voltage level. The impedance is such that both the output and the efficiency are maximum, and the second impedance is an impedance that maximizes both the output and the efficiency at a predetermined low battery voltage level, and is variable based on a switching signal from the outside. The first and second impedances of the impedance load circuit are switched.

  The cellular phone terminal of the present invention switches the impedance of the load circuit so that the battery voltage is high and low in a battery such as an alloy electrode battery without using a step-down DC-DC converter. It can respond with high efficiency. As a result, it is possible to extend the time during which the power amplifying device can be used by charging the battery once without increasing the device cost.

  Further, when in a predetermined operation mode, even if the battery voltage is within the voltage range corresponding to the high battery voltage level, the variable impedance load circuit is switched to the second impedance for the low voltage level, for example, HSDPA A power amplification operation suitable for the operation mode can be performed.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  FIG. 1 is a diagram showing a schematic configuration of a power amplifying apparatus according to the present invention together with its control unit. The power amplifying apparatus 100 normally includes an amplifier 102 connected to an input terminal IN connected to a modulation processing unit (not shown), and an impedance variable load circuit 130 that receives the output of the amplifier 102. The impedance variable load circuit 130 Is the output terminal OUT. The output terminal OUT is usually connected to an antenna duplexer (not shown). A voltage Vdd from the battery 108 is applied to the amplifier 102. The impedance variable load circuit 130 is switched between the first impedance and the second impedance according to the switching control signal 112a from the control unit 112. The control unit 112 outputs to the output of the voltage monitoring unit 112a that determines the threshold value of the voltage Vdd of the battery 108, the mode determination unit 112b that determines the operation mode of the transmission device such as the communication mode, and the voltage monitoring unit 112a and the mode determination unit 112b. In response, a switching signal generator 112c that generates a switching signal 112d having a predetermined level is included. In the present embodiment, mode determination unit 112b determines whether or not the communication mode selected in accordance with the operation of the operation unit by the user is HSDPA (High Speed Downlink Packet Access). Specific operation of the control unit 112 will be described later.

  FIG. 2 shows a first configuration example of the power amplifying apparatus 100 of FIG. Components similar to those shown in FIG. 1 are given the same reference numerals.

  First, the configuration will be described. The amplifier 102 includes a matching circuit 101 that receives an input signal from an input terminal IN, a first-source FET 103 that receives the output of the matching circuit 101 at a gate terminal, and a matching circuit 104 that has one end connected to the drain terminal of the FET 103. The other ends of the matching circuit 104 are connected to the gate terminal of the second source grounded FET 105, the drain terminals of the first and second FETs 103 and 105, and the coils 106 and 107 connected to the battery 108, respectively. Consists of. A transmission line having a predetermined length (1/4 wavelength of the signal) may be used instead of the coil.

  The variable impedance load circuit 130 includes a first load circuit 109 (ML11) having one end connected to the drain terminal of the second FET 105, and a second load circuit connected to the other end of the first load circuit 109. 110 (ML12), a connection point between both load circuits, and a two-input one-output switch circuit 111 having input terminals 111a and 111b connected to the other end of the second load circuit 110, respectively. The output terminal 111c becomes the output terminal OUT of the amplification device 100.

  FIG. 3 shows a specific circuit configuration example of the variable impedance load circuit 130. In this example, the load circuit 109 is composed of an LC circuit including a coil 109a having one end connected to the input terminal of the variable impedance load circuit 130, and a capacitor 109b having one end connected to the other end and the other end grounded. The Similarly, the load circuit 110 is composed of an LC circuit including a coil 110a and a capacitor 110b.

This power amplifying device is divided into two types according to the switch circuit 111, when the load impedance of the second FET 105 is the first impedance (ML11) and when the load impedance is the second impedance (ML11 + ML12). For both cases, the impedance seen from the drain end of the second FET 105 is shown on the Smith chart of FIG.

Preferable numerical examples of the first impedance (ML11) and the second impedance (ML11 + ML12) are as follows, respectively.
ML11: (13 ± 5) + j (11 ± 4)
ML11 + ML12: (5 ± 2) + j (2 ± 2)

With respect to these two types of loads, the following three states are defined by considering the case where the battery voltage Vdd = 2.7V and Vdd = 3.5V.
State A: Load ML11 + ML12, Vdd = 2.7V
State B: Load ML11, Vdd = 3.5V
State C: Load ML11 + ML12, Vdd = 3.5V

  Each of these states exhibits the following characteristics. The state A is the optimum state in which both the output and efficiency at Vdd = 2.7V are maximized, that is, Vdd = 2.7V.

  The state B is the optimum state in which both the output and the efficiency become maximum when Vdd = 3.5V, that is, Vdd = 3.5V.

  State C is an optimum state with Vdd = 2.7V and Vdd = 3.5V.

  FIG. 6 shows input / output characteristics representing the relationship between input power and output power in these three states. States A and B show almost the same characteristics. Although not shown, the efficiency of both is the same. This indicates that Vdd = 3.5V and Vdd = 2.7V make it possible to reduce the power supply voltage while maintaining efficiency. In the state C, the optimum load at Vdd = 2.7V is maintained and the operation is performed at Vdd = 3.5V. Naturally, the efficiency is deteriorated, but the saturated output is increased.

  Depending on the conditions of the mobile phone terminal to be used, the control unit 112 can select the above three states so that the power amplifying apparatus 100 can be appropriately operated.

  More specifically, first consider the case of a HSDPA compatible terminal in a so-called FOMA terminal. Use a battery with a final voltage of 3.5V to supply power. For operations other than normal HSDPA, state B is used. This is to save current consumption by operating at maximum efficiency at Vdd = 3.5V. When transmitting in the HSDPA mode, the switch circuit 111 is switched to the state C. This is because HSDPA has a large peak factor, and is operated in a state of high saturation output in order to satisfy the distortion specification. Note that Vdd = 2.7V operation in HSDPA is not considered here.

  Next, consider the case of using a long-life battery. As described above, when the alloy electrode battery as shown in FIG. 5 is used, the end voltage decreases to about 2.7 V as a price for the increase in capacity. In such applications, the power amplifying device also needs to operate at Vdd = 2.7V. In the alloy electrode battery of FIG. 5, since the initial charge is as high as Vdd = 4.2 V, the battery is operated in the state B here. When the battery voltage decreases and Vdd <3.5 V, the switch circuit 111 is switched to state A, and the output and efficiency are set to be optimal conditions at a low voltage.

  Table 1 shows measured values of adjacent distortion when CDMA2000 and W-CDMA (FOMA) HSDPA modulation signals are applied to the above operation. Both satisfy the standard value.

  Next, FIG. 7 shows a second configuration example of the power amplifying apparatus 100 of FIG. Constituent elements similar to those shown in FIG. 2 are given the same reference numerals, and redundant descriptions are omitted. The difference from FIG. 2 is the internal configuration of the load circuit. Although the load circuit 130a in FIG. 7 is similar to the load circuit 130 in FIG. 2, another switch circuit 114 is added to the input terminal 111b of the switch circuit 111. One end 114a of the switch circuit 114 is connected to the input terminal 111b of the switch circuit 111, and the other end 114b is grounded. The switch circuit 111 and the switch circuit 114 are switched in conjunction with each other in accordance with a switching control signal 112d from the control unit 112. In this example, when the movable contact of the switch circuit 111 is connected to the input terminal 111a, the switch circuit 114 is controlled to be turned on (conductive) so as to ground the output terminal of the second load circuit 110. . This prevents the impedance of the load circuit 130a from becoming unstable when one terminal of the load circuit 110 is opened. State A and state B are the same as in FIG.

  FIG. 8 shows a third configuration example of the power amplifying apparatus 100 of FIG. Constituent elements similar to those shown in FIG. 7 are given the same reference numerals, and redundant descriptions are omitted. The difference from FIG. 7 is the internal configuration of the load circuit. Although the load circuit 130b of FIG. 8 is similar to the load circuit 130a of FIG. 7, the output terminal of the second load circuit 110 is directly used as the output terminal OUT of the amplifier 100, and the first load circuit (ML31). The connection point of the second load circuit 110 (ML32) is connected to one end 114a of the switch circuit 114, and the other end 114b of the switch circuit 114 is grounded via the third load circuit 115 (ML33). State A and state B are realized by switching the switch circuit 114. In the third configuration example, the switch circuit is not directly inserted between the second FET 105 and the output terminal OUT as compared with the first and second configuration examples, so that the signal loss is small. The effect is obtained.

  FIG. 9 is a block diagram showing an outline of a hardware configuration of a mobile phone terminal 900 that can use the power amplifying apparatus of the present invention. This mobile phone terminal 900 includes an antenna 901, an antenna duplexer 902, a transmission / reception processing unit 903, a modulation / demodulation processing unit 905, a data processing unit 907, a voice input / output processing unit 909, a speaker 910, and the like. A microphone 912 is provided. The cellular phone terminal 900 also includes a control unit 925 (corresponding to the control unit 112 in FIG. 1) that includes a CPU, a ROM, and the like that control these elements, and is used as a work area and a temporary storage area for data by the control unit 925 A display unit 920 functioning as a user interface, and an operation unit 923 corresponding to the various operation keys. The power amplifying apparatus 100 of the present invention is located in the transmission / reception processing unit 903.

  The preferred embodiments of the present invention have been described above, but various modifications and changes other than those mentioned above can be made.

It is the figure which showed schematic structure of the power amplifier by this invention with the control part. It is a figure which shows the 1st structural example of the power amplification apparatus of FIG. It is a figure which shows the specific circuit structural example of the impedance variable load circuit shown in FIG. 1, FIG. It is a Smith chart which shows the impedance characteristic of the load circuit shown in FIG. It is a graph showing the difference in the characteristic of a carbon electrode system battery and an alloy electrode battery. It is a graph which shows the input-output characteristic showing the relationship between the input power and output power in three states in embodiment of this invention. It is a figure which shows the 2nd structural example of the power amplification apparatus of FIG. It is a figure which shows the 3rd structural example of the power amplification apparatus of FIG. It is a block diagram which shows the outline of the hardware constitutions of the mobile telephone terminal which can use the power amplifier of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Power amplifier 101 ... Matching circuit 102 ... Amplifier 103 ... Common source FET 104 ... Matching circuit 106, 107 ... Coil 108 ... Battery 109 ... Load circuit 110 ... Load circuit 111 ... Switch circuit 112 ... Control unit, 112a ... Voltage monitoring unit, 112b ... Mode determination unit, 112c ... Switching signal generation unit, 112d ... Switching control signal, 114 ... Switch circuit, 115 ... Load circuit, 130 ... Impedance variable load circuit, 130a, 130b ... load circuit, 900 ... mobile phone terminal

Claims (6)

It works with battery, and transmitting apparatus for transmitting a radio signal operating at low speed communication mode than selectively HSDPA communication mode and HSDPA communication mode as the operation mode, and control means for controlling the operation of the transmission device A mobile phone terminal provided,
The transmitting device includes a power amplifier, the power amplifier includes an amplifier for amplifying a signal to be transmitted, first impedance output and efficiency at a predetermined height battery voltage level as the load of the amplifier is maximized both And a variable impedance load circuit that switches a second impedance that maximizes both output and efficiency at a predetermined low battery voltage level ,
The control means selects a first impedance when the battery voltage is equal to or higher than a predetermined threshold, and a second state where the second impedance is selected when the battery voltage drops below a predetermined threshold. And a third state for selecting the second impedance when the battery voltage is equal to or higher than a predetermined threshold, and
The control means includes a voltage monitoring unit that monitors the voltage of the battery and a mode determination unit that determines an operation mode of the transmission device. When the operation mode is a communication mode slower than the HSDPA communication mode, the battery voltage is The first state is selected when the threshold is equal to or higher than a predetermined threshold, the second state is selected when the threshold is lower than the predetermined threshold, and the third state is selected when the operation mode is the HSDPA communication mode. A mobile phone terminal. Said variable impedance load circuit, a first load circuit having one end connected to an output terminal of the amplifier, a second load circuit connected to the other end of said first load circuit, the first and second and a switch circuit having two inputs and one output which is switched controlled by the connection point of the second load circuit and the other end of said second load circuit and second input said control means, said power from the output terminal of the switching circuit 2. The mobile phone terminal according to claim 1, wherein an output of the amplifying device is obtained. The variable impedance load circuit includes a second switch circuit that grounds the other end of the second load circuit when the switch circuit selects a connection point of the first and second load circuits. The mobile phone terminal according to claim 2 . Said variable impedance load circuit, a first load circuit having one end connected to an output terminal of the amplifier, a second load circuit connected to the other end of said first load circuit, the first and second A switch circuit connected to the connection point of the second load circuit and grounded via the third load circuit by the control means, and obtaining the output of the front power amplifier from the other end of the second load circuit. The mobile phone terminal according to claim 1, wherein Said amplifier via a first source-grounded FET receiving a gate terminal of the input signal via a first matching circuit, the second matching circuit a signal output to the drain terminal of the first source-grounded FET And a drain terminal of each of the first and second source grounded FETs is connected to the battery via a coil or a transmission line of a predetermined length. mobile phone terminal according to claim 1,.   First impedance = (13 ± 5) + j (11 ± 4)
  Second impedance = (5 ± 2) + j (2 ± 2)
The mobile phone terminal according to claim 1, wherein:

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