JP2003347857A - High-frequency power amplifier transistor chip, high- frequency power amplifier module and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect a high-frequency power amplifier circuit for mobile communications, etc., from damages, based on its load impedance variation, make a system designer free from the design of a protective circuit applicable thereto and realize applications to various systems, with a low cost and compact constitution. <P>SOLUTION: A protection circuit has a circuit for detecting the collector voltage at the collector of a high-frequency power amplifier transistor during high frequency operation, and a circuit for dividing a current, depending on the collector voltage at the base of the transistor. The protective circuit is formed into one chip with the high-frequency power amplifier transistor. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency power amplifier transistor chip used in a high-frequency power amplifier, and a high-frequency power amplifier module having an input / output matching circuit mounted on a module substrate together with the chip.

[0002]

2. Description of the Related Art A high-frequency amplifier is composed of elements which are difficult to be formed on-chip together with transistors, such as elements constituting an impedance matching circuit, etc., so that individual parts may be used, or chip parts or film elements may be formed on a transistor chip. And a module substrate mounted on the same substrate. Then, the high-frequency input signal of the desired frequency is amplified by the amplifier and supplied to the load.
Designed to be consistent with However, it is general that load fluctuations cannot be avoided. Therefore, it is adopted that an isolator is added to the output side to always maintain an output load of 50Ω.
However, for mobile phone terminal applications, for example, the system is not provided with an isolator in terms of cost, size, and the like. In such a system, the load of the last stage amplifying transistor may have a voltage standing wave ratio (VSWR) fluctuating up to about 10: 1. At this time, the load characteristic curve in high frequency operation fluctuates significantly. If this load characteristic curve falls outside the safe operating area (ASO) of the transistor, the transistor will be destroyed. FIG. 5 specifically shows an example of an ASO region in a transistor having a common emitter. The horizontal axis of the graph indicates the collector-emitter voltage of the transistor, the vertical axis indicates the collector current, and the base current indicates the base current. _I C _{-V CE} characteristics when changing in step is shown. This figure 5
The region below the collector voltage / current indicated by the thick line
This is an O region, and if operated beyond this region, the transistor will be damaged by electrical or thermal factors. As a countermeasure, Japanese Patent Laid-Open No. 2000-3410 discloses a technique for detecting the collector voltage of the last transistor and supplying a feedback current to its base to protect the transistor.
No. 52 discloses this. In other words, a protection circuit is provided between the collector and base electrodes of the last-stage transistor to allow a feedback current to flow to the base electrode when a voltage of a predetermined value or more is applied to the collector electrode, and the configuration is shown in FIG. By providing the protection circuit 100 between the circuit points 105 and 106, a feedback circuit of the transistor 505 is formed via an AC-coupled input capacitor 547 to the transistor 505. According to this configuration, the protection circuit 100 serves as an active feedback circuit to supply a feedback current at an output voltage equal to or higher than a certain value and reduce the output voltage by reducing the gain. It is designed to fit inside.

[0003]

However, since the gate circuit is connected between the input terminal and the output terminal of the last-stage transistor, the parasitic capacitance component of the gate circuit acts as a feedback capacitance element and operates at a standard operating voltage. It is easy to directly affect the output signal waveform and amplification factor. In addition, although this configuration is also discussed in the above publication, GMS (Glob
al System for Mobile communication) applications require an AC coupling capacitance 547, and other applications do not. For this reason, the system design side requires an extra element for the protection circuit. As described above, the above-described protection method causes deterioration in characteristics, and further causes problems such as an increase in cost and a hindrance to downsizing.

It is an object of the present invention to provide a high-frequency power amplifier transistor chip and a high-frequency power amplifier module which can be used for a high-frequency power amplifier which realizes low cost and miniaturization without sacrificing characteristics.

[0005]

According to the present invention, there is provided a high-frequency power amplifying transistor chip, that is, a semiconductor device, which detects that a high-frequency power amplifying transistor and an output terminal of the high-frequency power amplifying transistor exceed a predetermined voltage, and detects the high-frequency power amplifying transistor. A protection circuit for bypassing the input signal current of the amplifying transistor from the high frequency power amplifying transistor is formed on the same semiconductor substrate.

As described above, according to the present invention, the case where the collector voltage (output terminal voltage) of the high-frequency power amplifying transistor exceeds a predetermined value (ie, the voltage in the ASO region) is detected, and the detected output is used to detect the high-frequency power. The high frequency input signal to the power amplification transistor is bypassed (shunted). That is, when the collector voltage of the high-frequency power amplifier transistor exceeds a certain value due to a change in output load, the state is detected, and as a result, a part of the base current of the high-frequency power amplifier transistor is shunted. The base current of the RF power amplifier transistor is thus reduced, thereby reducing the collector current. Thereby, the high frequency (R
F) Even if the output load fluctuates significantly during operation, the range of the load characteristic curve in the region where the collector voltage is high is automatically reduced as the collector current decreases. It is possible to greatly improve the breakdown strength during a load change.

Further, in the configuration of the present invention, since the protection circuit is not directly connected between the input terminal and the output terminal of the high-frequency power amplification transistor, only a part of the parasitic capacitance component of the protection circuit functions as a feedback capacitance element. Therefore, the influence on the output signal waveform and the amplification factor at the standard operating voltage is small, and it is not necessary to reduce the parasitic capacitance component.

As described above, such a protection method is not based on the feedback operation.
In any system, including the above, it has no effect on other operations. For this reason, in the present invention, the protection circuit is formed as one chip together with the high-frequency power amplification transistor. Therefore, the system design side is free from the concern that the output transistor is destroyed due to the fluctuation of the driven load, and can make the system without worrying about such measures. The system thus constructed does not cause characteristic deterioration due to the provision of the protection circuit, and further achieves cost reduction and miniaturization. In the present invention, since the high-frequency power amplification transistor and its protection circuit are formed on one chip as described above, the high-frequency power amplification module mounted on the same module substrate together with the input / output matching circuit is provided. . It is preferable that the protection circuit includes a voltage detection circuit that detects an output voltage of the high-frequency power amplification transistor and a shunt circuit that bypasses the input signal current from the high-frequency power amplification transistor. The voltage detection circuit connects a plurality of diode operating elements in series with the same polarity, the anode side of which is an input terminal, the cathode side is a ground terminal, and the first, preferably the first connected to the ground terminal. The terminal on the anode side of the diode is an output terminal. Alternatively, the voltage detection circuit has a collector electrode of a first transistor constituting a Vbe multiplier as an input terminal, and connects a first resistor between a collector and a base electrode of the first transistor; A second resistor is connected between the base and emitter electrodes of the first transistor, the emitter electrode of the second transistor is used as a ground terminal, and the collector and base electrodes of the second transistor are short-circuited to the emitter electrode of the first transistor. Connected to output terminal. On the other hand, the shunt circuit receives a detection signal from a voltage detection circuit at a base terminal of a bipolar transistor whose emitter terminal is connected to ground, and connects its collector terminal to the base (input terminal) of the high-frequency power amplification transistor.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to FIGS. (First Embodiment) FIG. 1 is a block diagram showing a first embodiment of the present invention. Reference numeral 4 denotes a semiconductor device as a high-frequency power amplification transistor chip. The chip 4 has the high-frequency power amplifying transistor 3 and a protection circuit formed thereon, and can therefore be called an IC chip. The protection circuit includes a voltage detection circuit 1 and a shunt circuit 2. An input high-frequency matching circuit 7 and an output high-frequency matching circuit 8 are provided at each of the input side terminal 5 and the output side terminal 6 of the IC chip 4. These are mounted on the same substrate and are mounted on a high-frequency power amplification module. 9. The emitter of the high-frequency power amplification transistor 3 is connected to the ground terminal 11 of the module 9 via the ground terminal 10 of the IC chip 4. The voltage detecting circuit 1 includes a diode 12 composed of an NPN transistor having a base and a collector short-circuited.
Are connected in series, the collector side of the uppermost diode 12 is connected to the collector voltage terminal 13 of the high-frequency power amplifier transistor 3, and the lowermost diode 1
The emitter side of 2 is grounded via the ground terminal 10 of the IC chip 4, and the base-collector short-circuited terminal of the lowermost diode 12 is the output terminal of the voltage detection circuit 1.
The shunt circuit 2 comprises an NPN transistor 14, the collector of which is connected to the base voltage terminal 15 of the high-frequency power amplifier transistor 3, the base of which is connected to the output terminal of the voltage detecting circuit 1, and the emitter of which is connected via the ground terminal 10. Grounded. The base bias terminal 16 and the collector power supply terminal 17 of the high-frequency power amplifier module 9 are connected to the base voltage terminal 15 and the collector voltage terminal 13, respectively. The high-frequency power amplifier module 9 has an input terminal 18 for a high-frequency signal connected to the high-frequency matching circuit 7 for input on the input side, and an output terminal 19 for a high-frequency signal connected to the high-frequency matching circuit 8 for output. On the output side, for example 90
When high frequency power of about 0 MHz and about 5 dBm is input to the input terminal 18, for example, high frequency power amplified to about 34 dBm is output from the output terminal 19 to the external load 20 of 50Ω.

FIG. 2 is a graph showing the correlation between the collector voltage of the high-frequency power amplifier transistor 3 on the horizontal axis and the voltage at the node where the base and collector of each diode of the voltage detecting diode 12 are short-circuited on the vertical axis. It is. In this graph, the line accompanied by the marker display indicates the voltage at the lowest node of the voltage detecting diode 12 where the base and collector are short-circuited. As the collector voltage of the high-frequency power amplifier transistor 3 increases from 0V,
In this case, since a diode having a threshold of about 1.3 V is connected in nine stages in series, 11.7 V which is nine times that of the diode is connected.
, All the diodes of the voltage detection diode 12 are turned on. Therefore, the collector voltage is 11.7V
Hereinafter, the output voltage from the voltage detection diode 12 is 1.3 V or less, and the output voltage exceeds 1.3 V when the collector voltage is 11.7 V or more. On the other hand, upon receiving the output voltage from the voltage detecting diode 12, the transistor 14 of the shunt circuit 2 having substantially the same threshold value becomes 1.
When the voltage exceeds 3 V, the channel opens and becomes conductive. Therefore, when the collector voltage of the high-frequency power amplifying transistor 3 exceeds 11.7 V, the transistor 14 of the shunt circuit 2
Has a voltage of 1.3 V or more, has the effect of diverting a part of the base current of the high-frequency power amplification transistor 3 as the collector current of the transistor 14, and reducing the base current of the high-frequency power amplification transistor 3. FIG. 3 is a graph showing the correlation between the collector current and the collector voltage of the high-frequency power amplification transistor 3 when the protection circuit is added. When the collector voltage exceeds 11.7 V, the base current supplied to the base of the high-frequency power amplification transistor 3 by the transistor 14 of the shunt circuit 2 decreases, so that the collector current also decreases. As described in the above description of the operation, the collector voltage becomes 11.7 V due to the load fluctuation.
, The collector current decreases, and the range of the load characteristic curve is automatically reduced. Accordingly, the operation in the ASO region shown inside the bold line in FIG. 5 becomes possible. Accordingly, even when the output load fluctuates, for example, about VSWR 10: 1 during the RF operation, the operation can be performed in the ASO region, and the breakdown strength at the time of load fluctuation can be improved. Under the condition that the transistor has a collector voltage of 4 V, for example, when the load is 50Ω, the voltage swing is about 9 V at the maximum, and does not affect the normal operation when the load is 50Ω. Also, VS
When the load fluctuates to about WR10: 1, the voltage swing is about 20 V at the maximum, and the operation in the ASO region becomes possible. As described above, in the present invention, the high-frequency power amplifying transistor 3 and its protection circuits 1 and 2 are integrated to constitute the high-frequency power amplifying transistor chip 4, and further, the high-frequency power module together with the input / output matching circuits 7 and 8. 9 is mounted on one module substrate. Therefore, from the viewpoint of the system designer, it is not necessary to consider the protection of the transistor as a problem on the system side, and the cost and the size can be reduced. Further, there is no problem such as characteristic deterioration and limitation due to the provision of the protection circuit.

(Second Embodiment) Next, a second embodiment will be described. FIG. 4 is a circuit diagram of a voltage detection circuit in the protection circuit according to the second embodiment of the present invention. In the present embodiment, the invention is an embodiment in which the invention is applied to a voltage detection circuit 21 including a transistor constituting a Vbe multiplier as a voltage detection circuit. The collector electrode of the first transistor 22 constituting the Vbe multiplier is used as the input terminal 23 of the voltage detecting circuit 21, a first dividing resistor 24 is connected between the collector and base electrodes, and the second dividing resistor 24 is connected between the base and emitter electrodes. The resistor 25 is connected and the second
The emitter electrode of the transistor 26 is a ground terminal 27, the collector and base electrodes of the second transistor 26 are short-circuited and connected to the emitter electrode of the first transistor 22, and the output terminal 28 of the voltage detection circuit 21 is connected. It has a configuration to be. A plurality of voltage detecting diodes 1 of FIG.
2, the input terminal 23 is connected to the collector voltage terminal 13 of the high-frequency power amplifier transistor 3.
And the output terminal 28 is connected to the transistor 1 of the shunt circuit 2.
4 is connected to the base.

The voltage detecting circuit 21 includes a first divided resistor 2
4 and the resistance ratio of the second divisional resistor 25 can be arbitrarily selected to be turned on at an arbitrary multiple of the threshold value of the transistor. For example, the first divisional resistance 24 is 800Ω and the second divisional resistance 25 is 100Ω. Can be turned on at a voltage eight times the threshold value of the transistor. With this configuration, similarly to the operation of the first embodiment, the operating high-frequency power amplifying transistor 3 is connected to a desired ASO
It is possible to operate in the area, and it can be expected to have the effect of greatly improving the breakdown strength when the load changes.
In addition, the circuit area on the chip can be reduced.

[0013]

In the high-frequency power amplifying transistor and module, a circuit for detecting a collector voltage during high-frequency operation is provided on the collector side of the transistor, and a current is diverted to the base side of the transistor depending on the collector voltage. By incorporating a protection circuit having a circuit in the high-frequency power amplifier transistor, when the collector voltage of the transistor exceeds a certain value, the voltage detection circuit gives a value exceeding the threshold as an output voltage to the shunt circuit, and receives this output voltage. Therefore, the shunt circuit having substantially the same threshold value becomes conductive and reduces the base current by shunting a part of the base current of the high-frequency power amplification transistor,
As a result, the collector current is reduced. With this, RF
During operation, even if the output load fluctuates significantly, the range of the load characteristic curve in the region where the collector voltage is high is automatically reduced as the collector current decreases.
The operating current can be maintained in the O region, and the breakdown strength during a load change can be greatly improved. Further, in the configuration of the present invention, since the protection circuit is not directly connected between the input terminal and the output terminal of the high-frequency power amplification transistor, only a part of the parasitic capacitance component of the protection circuit functions as a feedback capacitance element. In addition, there is little influence on the output signal waveform and the amplification factor at the standard operating voltage, and there is no need to consider reducing the parasitic capacitance component.

[Brief description of the drawings]

FIG. 1 is an equivalent circuit diagram showing a first embodiment of the present invention.

FIG. 2 shows the high-frequency power amplification transistor 3 of FIG. 1 of the present invention.
FIG. 4 is a characteristic diagram showing a correlation between the collector voltage of FIG.

FIG. 3 shows the high-frequency power amplifying transistor 3 of FIG. 1 of the present invention.
FIG. 4 is a characteristic diagram showing a correlation between the collector current and the collector voltage of FIG.

FIG. 4 is a circuit diagram of a voltage detection circuit in a protection circuit according to a second embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a correlation between a collector current and a collector voltage of a conventional high-frequency power amplification transistor and a safe operation area.

FIG. 6 is a circuit diagram showing a conventional example.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 voltage detection circuit 2 shunt circuit 3 high-frequency power amplification transistor 4 high-frequency power amplification transistor (semiconductor device, IC chip) 7 high-frequency matching circuit for input 8 high-frequency matching circuit for output 9 high-frequency power amplification module

Continuation of front page    F-term (reference) 5J091 AA04 AA41 CA57 FA11 HA02                       HA19 HA25 HA29 KA00 KA20                       KA29 MA11 SA13 TA02                 5J500 AA04 AA41 AC57 AF11 AH02                       AH19 AH25 AH29 AK00 AK20                       AK29 AM11 AS13 AT02

Claims (9)

[Claims] 1. A high-frequency power amplification transistor, and a protection circuit for detecting that an output terminal of the high-frequency power amplification transistor has exceeded a predetermined voltage and bypassing an input signal current of the high-frequency power amplification transistor from the high-frequency power amplification transistor. Are formed on the same semiconductor substrate. 2. The voltage detection circuit according to claim 1, wherein the protection circuit includes a voltage detection circuit for detecting an output voltage of the high-frequency power amplification transistor, and a shunt circuit for bypassing the input signal current from the high-frequency power amplification transistor. 2. The high-frequency power amplifier transistor chip according to claim 1, wherein the circuit includes a plurality of diode operating elements connected in series, and a detection output is extracted from a predetermined number of diode operating elements. 3. The voltage detection circuit according to claim 1, wherein the protection circuit includes a voltage detection circuit for detecting an output voltage of the high-frequency power amplification transistor, and a shunt circuit for bypassing the input signal current from the high-frequency power amplification transistor. Circuit is the first
A collector electrode of the first transistor as an input terminal, connecting a first resistor between the collector and base electrodes of the first transistor, connecting a second resistor between the base and emitter electrodes of the first transistor, 2. The high-frequency device according to claim 1, wherein an emitter electrode of the first transistor is used as a ground terminal, and a collector and a base electrode of the second transistor are short-circuited and connected to an emitter electrode of the first transistor. Power amplification transistor chip. 4. The protection circuit includes a voltage detection circuit for detecting an output voltage of the high-frequency power amplification transistor, and a shunt circuit that bypasses the input signal current from the high-frequency power amplification transistor. And a base terminal of the bipolar transistor whose emitter terminal is connected to ground, receives a detection signal from the voltage detection circuit, and has a collector terminal connected to an input terminal of the high-frequency power amplification transistor. 3. The high-frequency power amplifying transistor chip according to any one of 3. 5. A high-frequency power amplification transistor and a protection circuit for detecting that an output terminal of the high-frequency power amplification transistor has exceeded a predetermined voltage and bypassing an input signal current of the high-frequency power amplification transistor from the high-frequency power amplification transistor. A high-frequency power amplification transistor chip formed on the same semiconductor substrate, an input matching circuit provided at an input terminal of the high-frequency power amplification transistor, and an output matching circuit provided at an output terminal of the high-frequency power amplification transistor. A high-frequency power amplification module mounted on a module substrate. 6. An input terminal of a voltage detection circuit is connected to an output terminal of an amplifying transistor, an output terminal of the voltage detection circuit is connected to an input terminal of a shunt circuit, and an output terminal of the shunt circuit is connected to the amplification terminal. A semiconductor device which is connected to an input terminal of a transistor for output, wherein an output current decreases when an output terminal voltage of the transistor for amplification becomes equal to or higher than a predetermined voltage. 7. The voltage detection circuit according to claim 1, wherein a plurality of diodes are connected in series with the same polarity, the anode side is used as an input terminal, the cathode side is used as a ground terminal, and the anode side of the first diode connected to the ground terminal is used. 7. The semiconductor device according to claim 6, wherein said terminal is an output terminal. 8. The voltage detecting circuit has a collector electrode of a first transistor constituting a Vbe multiplier as an input terminal, a first resistor connected between a collector and a base electrode, and a second resistor connected between a base and an emitter electrode. Connect the resistor and the second
7. The transistor according to claim 6, wherein the emitter electrode of said transistor is a ground terminal, and the collector and base electrodes of said second transistor are short-circuited and connected to the emitter electrode of said first transistor to form an output terminal. 13. The semiconductor device according to claim 1. 9. The shunt circuit according to claim 6, wherein a base terminal of the bipolar transistor whose emitter terminal is connected to the ground is used as an input terminal, and a collector terminal is used as an output terminal. Semiconductor device.