JPH10215128A - Transmission circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a circuit scale. SOLUTION: This circuit is provided with plural, two for instance, signal input terminals 11 and 12 and adjusts the voltage of respective signals RFin1 and RFin2. In this case, attenuators 13 and 14 are provided for the respective input routes of the respective signals RFin1 and RFin2 and the signals RFin1 and RFin2 are selected by the signal changeover switch 15 of the post stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission circuit having a plurality of signal input terminals, for adjusting the power of a signal input from each of these signal input terminals, and transmitting the adjusted signal to a next circuit. Telephone, PHS (Personal Handy-phon)
e.) and a transmission circuit suitable for use in processing a plurality of mobile communication signals such as a wireless LAN (Local Area Network) to select a desired signal and adjust the gain.

[0002]

2. Description of the Related Art In recent years, the development of mobile communication has been remarkable,
In Japan alone, a plurality of communication systems such as cellular telephones and PHS have been commercialized. Further, even the same cellular telephone handles a plurality of frequencies such as the 800 MHz band and the 1.5 GHz band. In addition, wireless LA
N and next-generation mobile communication systems are planned, and overseas GSM (Global System for Mobile Communications),
When PCS (Personal Commu-nications Services) and the like are combined, the number of mobile communication systems and frequencies used increase considerably.

[0003] Against this background, portable terminals called multifunction devices capable of simultaneously handling different communication systems are being developed. Various types of MFPs are conceivable. For example, in Japan, there are terminals that can use vacant lines in the 800 MHz band and 1.5 GHz band with one cellular phone, or terminals that can use the cellular while moving by car or the like and use it as a PHS while stopping. Conceivable. In addition, a terminal that can relay data communication via a PHS and a wireless LAN in addition to a voice signal is also conceivable. Overseas, for example, in the United States, PCS operators vary from state to state, but mobile terminals that can be used anywhere. In addition, it is possible to develop mobile devices that can be used in most countries.

A hardware bottleneck in these plans is that the RF block must use a different one depending on the communication system and frequency. This is because a different impedance matching circuit must be used for each frequency in order to process an RF signal. On the other hand, since the RF block uses a considerable amount of power and volume among portable terminals, how to design the RF block with low power consumption is the key to the development of a composite portable terminal. Above all, to the antenna R
A transmission circuit that performs signal amplification for transmitting the F signal determines most of the power consumption.

[0005]

By the way, when a transmission circuit with a power adjusting function for selectively amplifying, for example, two RF signals is designed using the prior art, the result is as shown in FIG. That is, in FIG. 7, two signal input terminals 10
1, 102, RF signal amplifier circuits 103, 104 connected to each of these signal input terminals 101, 102, and a power supply switch for selectively supplying a power supply voltage Vdd to these RF signal amplifier circuits 103, 104 105
And a signal changeover switch 107 for selectively supplying each output signal of the RF signal amplification circuits 103 and 104 to the antenna 106.

[0006] The RF signal amplifying circuit 103 includes an impedance matching circuit 111, an attenuator 112, an impedance matching circuit 113, and a power amplifier (medium power) 114. The RF signal amplification circuit 104 includes an impedance matching circuit 121, an attenuator 122, an impedance matching circuit 123, a power amplifier (medium power) 12
4. It comprises an impedance matching circuit 125 and a power amplifier (high power) 126.

As described above, in the case of a transmission circuit having two independent RF signal amplifier circuits 103 and 104, two circuits having substantially the same configuration are provided.
Simple but large circuit size. The power supply voltage V supplied to the two RF signal amplifier circuits 103 and 104
In order to suppress power consumption by switching dd, the power supply switch 105 is required, and the circuit scale is further increased.

[0008] If the integration of the transmission circuit is advanced, it can be said that there are great advantages in terms of cost and mounting area of the composite portable terminal. However, the transmission circuit having the circuit configuration of FIG. 7 has a large circuit scale for the above-described reason, and a large-sized element must be used as the power supply switch 105 to reduce the loss. Is difficult.

Therefore, in order to advance the integration, as shown in FIG. 8, it is conceivable to use a common amplifier and reduce the circuit scale. That is, in FIG. 8, two signal input terminals 201 and 202 and these signal input terminals 20
And a signal changeover switch 203 for switching each signal from the output signals 202 and 202 and the attenuator 20 with a 50Ω matching circuit.
4, an impedance matching circuit 205, a power amplifier (medium power) 206, a signal changeover switch 207 for distributing an output signal of the power amplifier 206 to two signal paths 208 and 209, and one signal path 208 is directly connected. An impedance matching circuit 211 and a power amplifier (high power) 212 are connected between the antenna 210 and the other signal path 209.

As described above, the attenuator 204, the impedance matching circuit 205, and the power amplifier 206 are shared, and each signal is directly transmitted to the signal changeover switches 203, 20.
In the transmission circuit configured to switch at 7, the attenuator 20
No. 4 needs to perform an operation independent of frequency (matching of 50Ω). For this purpose, a large-sized FET (field-effect transistor) or a capacitor, which is a circuit element constituting the attenuator 204, must be used.
As a result, it is difficult to proceed with chip integration.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a transmission circuit capable of reducing the circuit scale.

[0012]

A transmission circuit according to the present invention has a plurality of signal input terminals and a plurality of signal paths connected to each of the signal input terminals. A transmission circuit that performs power adjustment of an input signal and transmits the signal to a next-stage circuit, and includes a plurality of power adjustment circuits provided for a plurality of signal paths and formed on the same substrate. Has become.

In the transmission circuit having the above configuration, the power adjustment circuit provided for each signal path does not need to operate independently of frequency, but may be adjusted to a single frequency. Therefore, the size of the circuit elements constituting each of the power adjustment circuits can be small. As a result, the circuit scale can be reduced.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. In FIG. 1, input terminals of attenuators 13 and 14 as power control circuits are connected to, for example, two signal input terminals 11 and 12. The attenuators 13 and 14 have an impedance matching circuit as described later. At the output terminals of the attenuators 13 and 14,
Two input terminals of the two-input / one-output signal changeover switch 15 are connected to each other. Signal switch 1
5 is connected to the input terminal of the impedance matching circuit 16. The output terminal of the impedance matching circuit 16 is connected to the input terminal of a power amplifier (medium power) 17.

An output terminal of the power amplifier 17 is connected to an input terminal of a one-input / two-output signal changeover switch 18. Of the two output terminals of the signal changeover switch 18,
One output terminal is directly connected to the input terminal of the antenna 19, and the other output terminal is connected to the input terminal of the impedance matching circuit 20. An output terminal of the impedance matching circuit 20 is connected to an input terminal of a power amplifier (high power) 21. The output terminal of the power amplifier 21 has an antenna 1
Nine input terminals are connected.

FIG. 2 shows an example of a specific circuit configuration of the attenuators 13 and 14. In FIG. 2, the signal input terminal 3
1 is connected to one end of a capacitor 32. The other end of the capacitor 32 is connected to one end of the resistor 33, one end of the capacitor 34, and the drain of the FET 35, respectively. The other end of the resistor 33 is connected to the control input 36. The control input terminal 36 has a control signal Vre
f is applied.

One end of a resistor 37 is connected to the gate of the FET 35, and the other end of the resistor 37 is connected to a control input terminal 38. The control input terminal 38 has a control signal Vag
c is applied. One end of the resistor 39 and one end of the capacitor 40 are connected to the source of the FET 35. Resistance 3
The other end of 9 is connected to a control input end 36. The other end of the capacitor 40 is connected to a signal output terminal 41.

The other end of the capacitor 34 is connected to the drain of the FET 42. One end of a capacitor 43 is connected to the source of the FET 42, and the other end of the capacitor 43 is grounded. One end of a resistor 44 is connected to the gate of the FET 42, and the other end of the resistor 44 is connected to the control input terminal 36. One end of each of the resistors 46 and 47 is connected to the drain and the source of the FET 42, and the other ends of the resistors 46 and 47 are connected to the control input end 38.

In the attenuators 13 and 14 having the above-described structures, gallium arsenide FETs having excellent high-frequency characteristics are used as the FETs 35 and 42. The FET 35 controls the control signal Vref and the control signal Vagc.
Functions as a variable resistor that attenuates a signal in accordance with the potential difference between the two. Further, the FET 42 forms a shunt path for flowing a signal to the ground according to the potential difference. Capacitor 3
Reference numerals 2 and 40 function as a DC cutoff and also function as an impedance matching circuit.

Since the current consumption of the attenuators 13 and 14 is about several tens of μA, the total power consumption can be suppressed even if the attenuators 13 and 14 are simultaneously operated regardless of the presence or absence of a signal. And FIG.
In the above, selection of the signals RFin1 and RFin2 is performed by a signal changeover switch 15 provided at a stage subsequent to the attenuators 13 and 14.

The two attenuators 13, 1 in FIG.
FIG. 3 shows a configuration in which the components from No. 4 to the power amplifier 17 are integrated. 3, the same components as those in FIG. 1 are denoted by the same reference numerals, and two attenuators 13 and 14, a signal switch 15, and a semiconductor substrate 51 such as gallium arsenide are provided on the same substrate. An impedance matching circuit 16 and a power amplifier 17 are created. Gallium arsenide semiconductor substrates have excellent high frequency characteristics.

On the semiconductor substrate 51, a signal output terminal 52, two control terminals 53 and 54, and two switch switching terminals 55 and 56 are further formed. The output terminal of the power amplifier 17 is connected to the signal output terminal 52. Two control input terminals of the attenuators 13 and 14, that is, two control input terminals 36 and 38 in FIG. 2 are connected to the control terminals 53 and 54. Two control input terminals of the signal changeover switch 15 are connected to the switch changeover terminals 55 and 56.

The signals RFin1 and RFin2 are input to the signal input terminals 11 and 12, respectively, and the signal RFout is output from the signal output terminal 51. Also, 2
Control signals Vref and Vagc are applied to the two control terminals 23 and 24, respectively. Switch switching signals CTL1 and CTL2 are applied to the two switch switching terminals 55 and 56, respectively.

As described above, a plurality (two in this example)
Signal input terminals 11 and 12, and each signal RFin1,
In the transmission circuit for adjusting the power of RFin2, by providing the attenuators 13 and 14 for each input path of each signal RFin1 and RFin2, these attenuators 13 and 14 are provided.
14 is a single frequency (for example, 900 MHz, 1.9 G
Hz), the circuit elements (FIG. 2
Of the capacitor 32 and the FET 35) can be small.

As a result, since the circuit scale can be reduced, the chip area can be reduced and the integration with other circuits can be achieved. In addition, since each of the attenuators 13 and 14 has an impedance matching circuit (the capacitor 32 in this example), external components can be reduced.

In the circuit example of FIG. 2, the capacitor 32 is incorporated as an impedance matching circuit. However, if necessary, for example, a coil or a capacitor connected between the input terminal of the capacitor 32 and the ground may be incorporated. It is possible.

Further, in the present embodiment, the case where the present invention is applied to a transmission circuit having two signal input terminals has been described. However, the present invention is not limited to this, and n (n is an integer of 3 or more) signal transmission terminals are not limited thereto. The present invention is similarly applicable to a transmission circuit having an input terminal. In this case, the signal changeover switch 15
Can be handled by using a switch with n inputs and one output.

FIG. 4 is a block diagram showing another embodiment of the present invention. In FIG. 4, for example, input terminals of attenuators 63 and 64 are connected to two signal input terminals 61 and 62, respectively. As the attenuators 63 and 64,
For example, the one having the circuit configuration shown in FIG. 2 is used. The output terminals of the attenuators 63 and 64 are commonly connected to the input terminals of the impedance matching circuit 65. A power amplifier (medium power) 6 is connected to the output terminal of the impedance matching circuit 65.
6 input terminals are connected.

The output terminal of the power amplifier 66 is connected to the input terminal of a one-input / two-output signal changeover switch 67. Of the two output terminals of the signal switch 67,
One output terminal is directly connected to the input terminal of the antenna 68, and the other output terminal is connected to the input terminal of the impedance matching circuit 69. The output terminal of the impedance matching circuit 69 is connected to the input terminal of a power amplifier (high power) 70. The output terminal of the power amplifier 70 has an antenna 6
8 input terminals are connected.

That is, in the case of the first embodiment, for example, a signal changeover switch 15 is provided for two input paths, and the signal changeover switch 15 controls the signal RF.
In this embodiment, the signal changeover switch 15 is omitted and the two attenuators 63 and 64 are selectively operated, while the signal RFin1 and RFin2 are selectively operated.
It is configured to switch in2.

In order to switch between the signals RFin1 and RFin2 in the two attenuators 63 and 64, for example, when adjusting and amplifying the power of the signal RFin1 from the signal input terminal 61, only the attenuator 63 on the signal path used is used. Is operated so that the attenuation of the attenuator 64 on the unused signal path side is maximized. As a result, since the unused signal path has the maximum attenuation, the output signal of the attenuator 63 does not flow into the other attenuators 64, and is all transmitted to the power amplifier 66 via the impedance matching circuit 65.

The two attenuators 63 and 6 in FIG.
FIG. 5 shows a configuration in the case where the components from No. 4 to the power amplifier 66 are integrated. In FIG. 5, the same components as those in FIG. 4 are denoted by the same reference numerals, and are provided on the same substrate, for example, a semiconductor substrate 71 such as gallium arsenide excellent in high frequency characteristics.
Two attenuators 63 and 64, an impedance matching circuit 65, and a power amplifier 66 are created.

On the semiconductor substrate 71, a signal output terminal 72 and three control terminals 73, 74,
75 are formed. The output terminal of the power amplifier 66 is connected to the signal output terminal 72. Control terminal 7
The control input terminals 3 and 74 are connected to one control input terminal of each of the attenuators 63 and 64, that is, the control input terminal 36 in FIG. The control terminal 75 has an attenuator 6
The other control input terminals 3 and 64, that is, the control input terminal 38 in FIG. 2 are commonly connected.

The signals RFin1 and RFin2 are input to the signal input terminals 61 and 62, respectively, and the signal RFout is output from the signal output terminal 72. A control signal Vref1 for controlling the attenuation of the attenuator 63 is applied to the control terminal 73, and a control signal Vref2 for controlling the attenuation of the attenuator 64 is applied to the control terminal 74. In addition, the control terminal 75
A control signal Vagc for controlling the attenuation of the attenuators 63 and 64 is applied.

Signal RFi generated by attenuators 63 and 64
In selecting n1 and RFin2, two control signals Vref and Va are used in the circuit configuration shown in FIG.
It is performed by opening and closing a signal path with a potential difference of gc. Specifically, the potential of the control signal Vref of the unused attenuator is set to the control signal Vag.
By setting the potential sufficiently higher than the potential of c, the attenuation of the attenuator is maximized, and the signal path is equivalently cut off.

As an example, when the control signal Vagc is set to about 1 to 2.5 V, the control signal Vagc
Ref can be realized by setting a voltage of about 3 V for the attenuator on the signal path side not used. This voltage is equal to R which is commonly used in RF blocks.
Since it is the same as the control voltage of the F switch (0 V to 3 V), there is no need to prepare a new power supply.

As described above, a plurality (two in this example)
Signal input terminals 61 and 62, and each signal RFin1,
In the transmission circuit for adjusting the power of RFin2, by providing the attenuators 63 and 64 for each of the input paths of the signals RFin1 and RFin2, the same operation and effect as in the first embodiment can be obtained.

In addition, in the present embodiment, the first
Without using the signal changeover switch 15 in the embodiment,
By operating only the attenuator on the desired signal path and switching the signal so that the attenuator on the unused signal path has the maximum attenuation, loss in the switch may occur compared to the first embodiment. Without transmitting signals efficiently.
The circuit scale can be reduced by the omission of the switch, which is more useful for reducing the chip area.

For example, as shown in FIG. 8, when the attenuator 204 is shared for a plurality of signal inputs,
Since the attenuator 204 needs to operate in a frequency-independent manner, a large-sized circuit element must be used. For example, the chip size is about 1.1 mm × about 0.95. Was.
On the other hand, when an attenuator is provided for each signal path, each attenuator only needs to be adjusted to a single frequency, and the size of the circuit element can be small. Therefore, as shown in FIG. , 64 as well as the impedance matching circuit 65 and the power amplifier 66, a chip size of about 1.1 mm × 0.8 mm is sufficient.

In the case shown in FIG. 5, the components from the two attenuators 63 and 64 to the power amplifier 66 are integrated. However, as shown in FIG. 6, the components up to the signal switch 67 may be integrated. If necessary, the subsequent circuits, that is, the impedance matching circuit 69 and the power amplifier 70 in FIG. 4 can be integrated.

In the present embodiment, the case where the present invention is applied to a transmission circuit having two signal input terminals has been described. However, the present invention is not limited to this, and n (n is an integer of 3 or more) signal signals The present invention is similarly applicable to a transmission circuit having an input terminal. In this case, by setting the attenuators of all unused signal paths among the n attenuators to the maximum attenuation, the desired signal can be transmitted to the subsequent impedance matching circuit without flowing into other signal paths. Can be done.

[0043]

As described above, according to the present invention,
In a transmission circuit that has multiple signal input terminals and adjusts the power of the signals in each signal path, by providing a power adjustment circuit for each signal path, each power adjustment circuit can be adjusted to a single frequency Since the size of the circuit elements to be configured can be reduced, the circuit scale can be reduced, and the chip area for integration can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram illustrating an example of a circuit configuration of an attenuator.

FIG. 3 is a block diagram showing a configuration in the case of integration according to the first embodiment.

FIG. 4 is a block diagram showing a second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration in the case of integration according to a second embodiment.

FIG. 6 is a block diagram showing a configuration for another integration according to the second embodiment.

FIG. 7 is a block diagram showing a transmission circuit according to a conventional example.

FIG. 8 is a block diagram showing a transmission circuit according to the problem.

[Explanation of symbols]

11, 12, 61, 62 Signal input terminal 13, 14, 63, 64 Attenuator 15, 18, 67 Signal changeover switch 16, 20, 65, 69 Impedance matching circuit 17, 66 Power amplifier (medium power) 21, 70 Power amplifier (High power)

Claims (7)

[Claims] A plurality of signal input terminals; a plurality of signal paths connected to each of the plurality of signal input terminals;
A transmission circuit for adjusting the power of a signal input from each of the plurality of signal input terminals and transmitting the signal to a next-stage circuit, provided for each of the plurality of signal paths, and formed on the same substrate. A transmission circuit comprising a plurality of power adjustment circuits. 2. The transmission circuit according to claim 1, further comprising switch means for selectively outputting one of the output signals of the plurality of power adjustment circuits. 3. The method of claim 1, wherein only one of said plurality of power conditioning circuits is selectively operable.
Transmission circuit as described. 4. The transmission circuit according to claim 1, wherein each of the plurality of power adjustment circuits has an impedance matching circuit at each input stage. 5. A power amplification circuit formed on the same substrate as the plurality of power adjustment circuits and amplifying power of a signal passing through the plurality of power adjustment circuits.
Transmission circuit as described. 6. The transmission circuit according to claim 1, wherein said substrate is a semiconductor substrate. 7. The transmission circuit according to claim 6, wherein said semiconductor substrate is a gallium arsenide semiconductor substrate.