JPH1188082A - Amplifier device and portable telephone system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption, to reduce an insertion loss and to prevent deterioration of a noise index without inserting a switch circuit into an input signal route against an amplifier when the gain is varied by bypassing the amplifier. SOLUTION: When a switch 57 inserted into the power supply route of a low noise amplifier(LNA) 54 is turned off, LNA 54 is not operated and a signal through a λ/4 strip line 50 is selected as output by the switch circuit 55. When the switch 57 is turned on, power is supplied to LNA 54 and LNA 54 becomes an operation state. The output side of a strip line 50 is grounded in terms of high frequency through a diode D1 and a capacitor C7 and the input impedance becomes infinite. The signal amplified by LNA 54 is selected in the switch circuit 55 as the output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an amplifying device whose gain can be varied by bypassing an amplifier, and to a portable telephone device using such an amplifying device.

[0002]

2. Description of the Related Art CDMA (code division multiple acce)
In the ss) type mobile phone device, the base station controls the output of the mobile station so as to change the intensity of radio waves according to the distance between the base station and the mobile station in each cell. That is, as the distance increases, the output of the mobile station increases. This is based on the reason that power consumption is reduced and interference with surrounding cells is not caused so that interference with the same frequency is hardly caused. In particular, in the CDMA system, power control is finer than in the TDMA (time division multiple access) system. Also,
The smaller the distance from the base station in the cell, the stronger the mobile station receives the radio wave. As a result, the transmission circuit and the reception circuit of the mobile station (specifically, the mobile phone) need to have a wide range of change in the gain of the amplifier, for example, 90 dB.

[0003] It has been difficult to realize such a wide change in gain using only an AGC amplifier provided in the IF stage.
Conventionally, as shown in FIG. 8, FET switch circuits 72 and 7 are provided on the input side and output side of an amplifier 71, respectively.
3 was provided. When the switch circuits 72 and 73 select one terminal A, the signal from the input terminal 74 is supplied to the amplifier 71 via the switch circuit 72, and the output signal of the amplifier 71 is supplied to the output terminal 7 via the switch circuit 73.
It is taken out to 5. The gain of the amplifier 71 has a range of, for example, 20 dB from the minimum to the maximum.

When switch circuits 72 and 73 select the other terminal B, amplifier 71 is bypassed. Therefore, the gain between the input terminal 74 and the output terminal 75 is 2
Decrease by 0 dB. As described above, when the range of the gain change of 90 dB is realized, 70 d after the output terminal 75.
An AGC amplifier having a B gain change range is connected.

[0005]

However, as in the conventional configuration, a switch circuit 72 is connected to the input side of the amplifier 71.
Is provided, the number of parts increases, and the switch circuit 7
2, the power consumption occurs, and the insertion loss of the switch circuit 72 causes a decrease in the receiving sensitivity. Further, switching on the input side of the amplifier 71, that is, switching at a small signal level before amplification has a problem of deteriorating NF (noise figure). The effect of the switch circuit 73 on the output side is relatively small.

Accordingly, an object of the present invention is to provide an amplifying apparatus which can omit the switch circuit on the input side when the gain is changed by bypassing the amplifier, and can avoid the above-mentioned problems caused by the switch circuit on the input side. A mobile phone device is provided.

[0007]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, there is provided an amplifying apparatus wherein the gain is variable by bypassing the amplifier by a switch means. An amplifying device not included in the input signal supply path.

According to a second aspect of the present invention, in the amplifying device wherein the gain is varied by bypassing the amplifier by the switch means, the input terminal is connected to the signal input terminal, and the output terminal is connected to the first switch means. And a second switch means is inserted between one of the power supply terminals and the power supply line. When the second switch means is turned on, power is supplied and the connection point is connected to a high frequency. An amplifier configured to be electrically grounded;
When one end is connected to the signal input terminal, the other end is connected to the connection point, and connected to the other terminal of the first switch means, and the other end is grounded at a high frequency, the input impedance increases. When the circuit means and the second switch means are turned off, the first switch means selects the signal passed through the circuit means, and when the second switch means is turned on, the first switch means selects the output of the amplifier. An amplifying device comprising: means for controlling first and second switch means so as to select a signal; and a signal output terminal from which a signal selected by the first switch means is taken out.

According to a seventh aspect of the present invention, there is provided a portable telephone apparatus provided with an amplifying device in which a gain is varied by bypassing an amplifier in a receiving unit and / or a transmitting unit by a switch unit, wherein the switch unit is provided for the amplifier. A mobile phone device not being included in an input signal supply path.

According to the present invention, the second power supply path of the amplifier
Switch means, the operation / non-operation of the amplifier is controlled by the second switch means, and the input impedance of the circuit means is switched at the same time. Therefore, there is no switching means in the input signal path of the amplifier, and the problems of power consumption, insertion loss, and noise figure deterioration due to the switching means do not occur. When the amplifier is disabled, no current flows through the second switch means, and power consumption can be reduced.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. In FIG. 1 showing the entire circuit configuration of the mobile phone device, reference numeral 1 denotes an antenna. The signal received by the antenna 1 is supplied to the receiving unit 2 via the antenna sharing device 11. The receiving unit 2 includes a mixer, an IF amplifier, and the like, as described later. The local oscillation signal from the local oscillator 3 is supplied to the receiving unit 2. The reception IF signal from the reception unit 2 is supplied to the modulation / demodulation and baseband processing unit 4, and processing such as demodulation and filtering is performed on the reception IF signal. The carrier signal from the receiving carrier oscillator 5 is used for demodulation. The audio signal received from the modulation / demodulation and baseband processing unit 4 is supplied to the audio processing unit 6, subjected to processing such as frequency characteristic correction and amplification, and supplied to the speaker 7.

The output of the microphone 8 is supplied to the modulation / demodulation and baseband processing unit 4 via the audio processing unit 6.
A carrier signal from the transmission carrier oscillator 9 is used for modulation. The modulation output is supplied to the transmission unit 10. The transmission unit 10 includes a mixer, an amplifier, and the like, and a local oscillation signal from the local oscillator 3 is supplied to the transmission unit 10 as described later. A transmission signal from the transmission unit 10 is supplied to the antenna 1 via the antenna sharing device 11.

Further, an operation unit 12 and a control unit 13 are provided. The operation unit 12 includes a push button, a rotary knob, and the like. The control unit 13 is usually composed of a microcomputer, and controls the operation of the entire mobile phone device.
Generates various control signals. Also, the detection level of the received RF signal, that is, data indicating the electric field strength of the received signal is supplied from the receiving unit 2 to the control unit 13 as shown by a broken line. The control unit 13 controls the gain of the AGC amplifier and the switch circuit by checking the electric field strength of the received signal.

FIG. 2A shows an example of the receiving section 2. A reception signal is supplied to the input terminal 21 from the antenna sharing device 11. The received signal is supplied to one terminal a of the switch circuit 22 composed of an FET and the RF amplifier 23, and the output signal of the RF amplifier 23 is supplied to the other terminal b of the switch circuit 22.
Supplied to The switch circuit 22 is controlled by a control signal from the control unit 13. When the received electric field strength is relatively strong, the switch circuit 22 selects the terminal a. Therefore, the amplifier 23 is bypassed. On the other hand, when the received electric field strength is relatively weak, the switch circuit 22 selects the terminal b. Therefore, the received signal is supplied to the RF filter 24 via the amplifier 23.

The output signal of the RF filter 24 is a mixer 25
Supplied to A local oscillation signal is supplied from the local oscillator 3 to the mixer 25, and an IF signal is output from the mixer 25. The IF signal is supplied to the AGC amplifier 27 via the IF filter 26. The AGC amplifier 27 controls the control unit 13
The gain is controlled by a gain control signal from the controller.
That is, when the received electric field intensity is relatively weak, the gain is increased, and when the received electric field intensity is relatively strong, the gain is decreased. An output signal of the AGC amplifier 27 is taken out to an output terminal 28. When a gain larger than the maximum value of the gain of the AGC amplifier 27 is required, the switch circuit 22 is controlled so as to select the terminal b, and the preceding amplifier 23 is inserted into the reception signal path.

FIG. 2B shows an example of the transmission unit 10. Signals I and Q are supplied to input terminals 31 and 32, respectively, and are modulated by an I / Q modulator 33. Modulation output is I
The signal is supplied to the mixer 35 via the AGC amplifier 34 of the F stage. A gain control signal is supplied from the control unit 13 to the AGC amplifier 34. Gain control is performed according to an instruction from the base station. Instead of the instruction, the AGC amplifier 34 may be controlled using the received electric field strength. Mixer 3
5 is supplied with a local oscillation signal from the local oscillator 3. The RF signal from the mixer 35 is supplied to the RF filter 36.

The output signal of the RF filter 36 is supplied to one terminal c of the switch circuit 37 and the amplifier 38, and the output signal of the amplifier 38 is supplied to the other terminal d of the switch circuit 37.
Supplied to The output signal of the switch circuit 37 is taken out to the output terminal 41 via the RF filter 39 and the power amplifier 40. The switch circuit 37 is controlled by the control unit 13. That is, in the range from the minimum gain of the AGC amplifier 34 to its maximum gain, the terminal c is selected to bypass the amplifier 38, and when a gain larger than the maximum gain is required, the terminal d is selected to transmit. An amplifier 38 is included in the signal path.

As can be seen from the configurations of the receiving section 2 of FIG. 2A and the transmitting section 10 of FIG. 2B, the switch circuit 22 for bypassing the amplifier 23 and the switch circuit 37 for bypassing the amplifier 38 , 38 are connected to respective outputs. Therefore, it is possible to avoid the problems of a decrease in receiving sensitivity and a deterioration in NF (noise figure) caused by connecting a switch circuit to the input side as in the related art.

The above-described amplifier 23 and switch circuit 2
2, and the amplifier 38 and the switch circuit 37 are each configured as an amplifier. Hereinafter, such an amplifying device will be described in more detail. First, an embodiment of an amplifying device using a λ / 4 strip line will be described. FIG. 3 is a diagram for explaining that the impedance viewed from the input side can be made infinite by opening or shorting the end of the λ / 4 strip line 50.

The λ / 4 strip line 50 is connected between an input terminal 51 and an output terminal 52. The power supply voltage Vcc is supplied to the input terminal 51 via the coil L, and a capacitor C is inserted between one end of the coil L and the ground. The output terminal 52 is grounded via a switching PIN diode D1. Generally, the impedance Z seen from the input side of the λ / 4 strip line 50
_in is represented by the following equation, where the characteristic impedance is Z ₀ .

Z _in = Z ₀ ((Z + jZ ₀ tan β lε)
/ (Z ₀ + jZtan β lε)) where β = 2π / λ (phase constant) and lε = λ / 4 length of the strip line.

The diode D1 is turned on, and the output terminal of the λ / 4 strip line 50 is short-circuited. That is, when (Z = 0) is substituted into the above equation, the impedance Zin becomes infinite as represented by the following equation. Utilizing this, the switch circuit on the input side is omitted by the λ / 4 strip line 50.

[0023] _{Z in = jZ 0 tan π /} 2 lε = j∞ Figure 4 illustrates one embodiment of the amplification system using a lambda / 4 stock lip line 50. 54 is LNA (low noise amp)
lifier). The LNA 54 is connected to the amplifier 23 (FIG. 2A).
Or 38 (FIG. 2B). The input terminal of the LNA 54 is connected to the input terminal 51, and the output terminal is connected to one terminal f of the switch circuit 55. Switch circuit 5
5 corresponds to the switch circuit 22 (FIG. 2A) or the switch circuit 37 (FIG. 2B).

One of the power terminals of the LNA 54 is grounded,
A series circuit of a switch 57 as a second switch, a first coil L2, a diode D1, and a second coil L4 is inserted between the other end and the power supply line 56. The connection point between the cathode of the diode D1 and the coil L4 is grounded at a high frequency via a capacitor C7. An input terminal 51 is connected to a connection point between the coil L2 and the anode of the diode D1 via the λ / 4 strip line 50 and the capacitor C3. This connection point is connected to the terminal e of the switch circuit 55 as the first switch means.

In the configuration shown in FIG.
This is for switching the operation / non-operation of the NA 54. The switch circuits 55 and 57 are controlled by a control signal from the control unit 13 in the case of a mobile phone device.
When the switch 57 is turned on, the switch 57, the coil L2, the diode D1, the coil L4, the LN
A current flows to the ground through A54. Thereby, the diode D1 turns on. That is, the output terminal of the λ / 4 strip line 50 is grounded (short-circuited) at high frequency.
Is done. As a result, as described with reference to FIG.
The impedance seen from the input side of the / 4 strip line 50 becomes infinite. Therefore, all input signals are LNA
It flows to the input side of 54.

When the switch 57 is turned off, power is not supplied to the LNA 54, and the LNA 54 enters an inoperative state. Further, the diode D1 is turned off. In this state,
The impedance as viewed from the input side of the LNA 54 increases, and the input signal all flows to the λ / 4 strip line 50 side.

In conjunction with the switch 57, the switch circuit 5
5 is controlled. That is, when the switch 57 is on, the terminal f is selected so as to select the output signal of the LNA 54, and when the switch 57 is off, the terminal f is selected so that the signal via the λ / 4 strip line 50 is selected. e
Is selected. In this way, by controlling the switch 57 inserted in the power supply system and the switch circuit 55 connected to the output side by the control signal from the control unit without connecting the switch circuit to the input signal path of the LNA 54,
The LNA 54 can be appropriately bypassed.

Λ is a value defined corresponding to the carrier frequency used in the mobile phone. For example, in the case of 800 MHz, λ is about 360 mm.
mm. Even if the wavelength shortening rate determined by the thickness of the substrate, its material and the like is about 0.6, the length becomes 54 mm. It is not easy to secure such a length on the substrate. Therefore, in another embodiment of the present invention, an LC circuit shown in FIG. 5 is used instead of the λ / 4 strip line 50.

In FIG. 5, the input terminal 61 and the output terminal 6
A coil L1 is inserted between the two, and capacitors C1 and C2 are inserted between both ends of the coil L1 and the ground, respectively.
A load 63 (for example, Z = 50Ω) is connected to the output terminal 62. A switching element 64 composed of a diode is inserted between the output terminal 62 and the ground.

When the switching element 64 is off,
When the capacitor C2 has a predetermined value, the impedance Z of the load 62 can be seen as it is from the input side. Further, when the switching element 64 is turned on and the capacitor C2 is short-circuited, the impedance seen from the input side becomes infinite due to the phase around the capacitor C1 and the coil L1. Such an operation is performed by appropriately selecting the value of each circuit element for a predetermined signal frequency.

FIG. 6 shows a circuit configuration of another embodiment of the present invention using an LC circuit. The LNA is constituted by a common-emitter type NPN transistor Q2. The base of the transistor Q2 is connected to the input terminal 5 via the capacitor C6.
Connected to 1. A PNP transistor Q1 as a switching element is inserted between the collector of the transistor Q2 and the power supply line 56. The emitter of the transistor Q1 is connected to the power supply line 56, and a control signal for switching on / off of the LNA is supplied to a terminal 58 derived from the base.

A series circuit including a coil L2, a PIN diode D1, and coils L4 and L5 is inserted between the collector of the transistor Q1 and the collector of the transistor Q2. A parallel circuit of a resistor R1 and a capacitor C4 is inserted between the collector of the transistor Q1 and the connection point between the coil L2 and ground. The connection point between the diode D1 and the coil L4 is grounded at a high frequency via a capacitor C7. The connection point between the coils L4 and L5 is grounded via the capacitor C8.

The input terminal 51 is connected to an LC circuit composed of the capacitors C1 and C2 and the coil L1, and to a connection point between the capacitor L2 and the diode D1 via the capacitor C3, as in the configuration shown in FIG. Further, the input terminal 51 is connected to the base of the transistor Q2 via the capacitor C6. A coil L3 and a resistor R4 are inserted between a connection point of the base of the transistor Q2 and the coils L4 and L5, and a connection point of the coil L3 and the resistor R4 is a capacitor C.
5 is grounded. Capacitor C6 and coil L
Numeral 3 is for impedance matching.

The connection point between the anode of the coil L2 and the diode D1 is connected to the switch circuit 55 via the capacitor C9.
Terminal e. The collector of transistor Q2 is connected to terminal f of switch circuit 55 via capacitor C10. The switch circuit 55 is controlled by a control signal similar to that supplied to the terminal 58. The output terminal of the switch circuit 55 is led out as the output terminal 52 via the capacitor C11.

The operation of the amplifying device having the configuration shown in FIG. 6 will be described below. First, the transistor Q1 is turned on by the low-level control signal, and the L
The operation when the NA is in the operating state will be described. In this state, the terminal f of the switch circuit 55 is selected. When the transistor Q1 turns on, the power supply voltage is supplied to the collector of the transistor Q2. At the same time diode D
Since a current flows through the capacitor 1, one end of the coil L1 is grounded (that is, short-circuited) via the capacitor C3, the diode D1, and the capacitor C7. Thereby, the LC circuit side including the capacitor C1 as viewed from the input terminal 51 has a high impedance. Therefore, an input signal (for example, a signal of 800 MHz) is applied to L
The signal is amplified by the NA and taken out to the output terminal 52 via the capacitor C10 and the terminal f of the switch circuit 55.

When the control signal goes high and the transistor Q1 is off, power is not supplied to the transistor Q2. Therefore, since no current flows through the diode D1, one end of the coil L1 is not short-circuited.
In this case, since the transistor Q2 is turned off, the input impedance on the LNA side becomes high, and the input signal becomes the LC circuit, the capacitor C3, the capacitor C9, and the switch circuit 5.
Output terminal 5 via the terminal e of terminal 5 and the capacitor C11.
It is taken out to 2. That is, the LNA is bypassed.

According to the circuit configuration shown in FIG. 6, the amplifier (LNA) can be bypassed without providing a switch circuit on the input side. Further, since the diode D1 is inserted in the power supply path to the collector of the transistor Q2, there is an advantage that wasteful power consumption does not occur when the LNA is in a non-operating state.

FIG. 7 shows still another embodiment of the amplifying device according to the present invention. Circuit elements corresponding to those in FIG. 6 are denoted by the same reference numerals. In the configuration of FIG.
A transistor Q1 for performing a switching operation is provided, and the terminal of the LC circuit is short-circuited by a diode D1. On the other hand, in the configuration of FIG. 7, the functions of the transistor Q1 and the diode D1 are realized by one FET Q3.

In FIG. 7, the drain of FET Q3 is connected to power supply line 56 via coil L2, and its source is connected to the collector of transistor Q2 via coils L4 and L5. A control signal for controlling ON / OFF of the LNA is supplied to a terminal 58 derived from the gate of the FET Q3. When the FET Q3 is on, power is supplied to the transistor Q2 and the LNA
Is in the operating state, and the termination of the LC circuit is the FET Q3.
And short circuit via the configuration C7, and the input impedance of the LC circuit becomes high. Therefore, the signal amplified by the LNA is output via the terminal f of the switch circuit 55. On the other hand, when the FET Q3 is off, the LNA becomes inactive, and the terminal e of the LC circuit and the switch circuit 55 is turned off.
The signal passed through is output, and the LNA is bypassed. The circuit configuration of FIG. 7 can reduce the number of circuit elements more than that of FIG.

[0040]

According to the present invention, when the gain is varied by bypassing the amplifier, a switch circuit is not required on the input side of the amplifier. Therefore, it is possible to achieve a reduction in the number of components, a reduction in power consumption, prevention of loss due to insertion of the switch circuit, and prevention of deterioration of NF (noise figure) due to insertion of the switch circuit. In addition, by applying the amplifying device according to the present invention to a transmitting or receiving circuit of a mobile phone device,
Similar effects can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a mobile phone device to which the present invention can be applied.

FIG. 2 is a block diagram illustrating a configuration of an example of a receiving unit and a transmitting unit of the mobile phone device.

FIG. 3 is a connection diagram for explaining a λ / 4 strip line used in an embodiment of the present invention;

FIG. 4 is a connection diagram of one embodiment of the present invention.

FIG. 5 is a connection diagram used for describing an LC circuit instead of a λ / 4 strip line used in another embodiment of the present invention.

FIG. 6 is a connection diagram of another embodiment of the present invention.

FIG. 7 is a connection diagram of still another embodiment of the present invention.

FIG. 8 is a connection diagram for explaining a conventional technique.

[Explanation of symbols]

2 ... receiving unit, 10 ... transmitting unit, 27, 34 ...
AGC amplifier, 50 ... λ / 4 strip line,
51 ... input terminal, 52 ... output terminal, 54 ...
LNA, 55 ... switch circuit

Claims (7)

[Claims] 1. An amplifying apparatus in which a gain is varied by bypassing an amplifier by a switch means, wherein the switch means is not included in an input signal supply path for the amplifier. 2. An amplifying device in which the gain is varied by bypassing an amplifier by a switch means, wherein an input terminal is connected to a signal input terminal, and an output terminal is connected to one terminal of the first switch means. A second switch is inserted between one of the power supply terminals and the power supply line, and power is supplied when the second switch is turned on, and the connection point is grounded at a high frequency. And one end thereof is connected to the signal input terminal, the other end is connected to the connection point, and the other end of the first switch means is connected, and the other end is connected to the high frequency Circuit means for increasing the input impedance when being electrically grounded; and, when the second switch means is turned off, a signal transmitted through the circuit means is supplied to the first switch. When the switch means selects and the second switch means is turned on, the first switch means selects the output signal of the amplifier.
An amplifying apparatus comprising: means for controlling the first and second switch means; and a signal output terminal from which a signal selected by the first switch means is extracted. 3. The amplifying apparatus according to claim 2, wherein said circuit means is a λ / 4 strip line. 4. The amplifying device according to claim 2, wherein said circuit means is an LC circuit comprising a coil and capacitors inserted between both ends of said coil and ground. 5. The switching device according to claim 2, wherein a switching element, a first coil, a diode, and a second coil are inserted between one of power supply terminals of the amplifier and a power supply line. The other end of the circuit means is connected to a connection point of the anode of the diode, and when the switching element is turned on, power is supplied to the amplifier, the diode is turned on, and the diode and the second coil are turned on. An amplifying device characterized in that a connection point is grounded at a high frequency. 6. The switching device according to claim 2, wherein a first coil, a switching element, and a second coil are inserted between one of power supply terminals of the amplifier and a power supply line, and the first coil and the switching coil are connected to each other. The other end of the circuit means is connected to a connection point of one terminal of the element, power is supplied to the amplifier when the switching element is turned on, and the other terminal of the switching element is connected to the second coil. Wherein the connection point is grounded in a high frequency manner. 7. A portable telephone device comprising an amplifying device in a receiving unit and / or a transmitting unit, the gain of which is changed by bypassing an amplifier by a switch means, wherein the switch means supplies an input signal to the amplifier. A mobile phone device not included in a road.