JP2005109644A - Semiconductor circuit, semiconductor device, and radio communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor circuit with a simple structure and a small scale capable of detecting a low power signal. <P>SOLUTION: The semiconductor circuit has a configuration wherein a base of a transistor TR 1 of a power amplifier circuit 1 is connected to a diode D1 of a detection circuit section 2 via a resistor R1. Thus, a voltage nearly equal to a base-emitter voltage of the transistor TR 1 of the power amplifier circuit 1 can be applied to the diode D1 of the detection circuit section 2. Succeedingly, it is possible to apply a forward bias voltage nearly equal to a threshold value of the diode D1 to the diode D1 of the detection circuit section 2. Accordingly, even when an input signal from the power amplifier circuit 1 to the detection circuit section 2 is low, a comparatively high detection voltage Vsense can be extracted from the detection circuit section 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor circuit having a detection circuit section and a signal processing section, a semiconductor device having the semiconductor circuit, and a wireless communication apparatus. The semiconductor circuit is, for example, a semiconductor circuit that is used in a wireless communication device that transmits and receives a high-frequency signal, a measurement device that measures output power of the high-frequency signal, and the like and has a detection circuit that detects high-frequency power.

  Conventionally, a high-frequency power detection circuit as shown in FIG. 9 has been proposed (Japanese Patent Laid-Open No. 4-207609: Patent Document 1). In this high-frequency power detection circuit, a capacitor C101 and a diode D101 are connected in series between an input terminal 101 and an output terminal 102, and a connection line 103 connecting the diode D101 and the output terminal 102 is connected to the ground. A capacitor C102 and a resistor R102 are connected in parallel.

  In this high frequency power detection circuit, when a high frequency signal is inputted to the input terminal 101, a DC voltage depending on the power of the inputted high frequency signal can be taken out by the capacitor C102 having a rectifying action of the diode D101 and a sufficiently large capacitance value. It is structured.

  The high-frequency power detection circuit shown in FIG. 9 performs diode detection, but detection by the diode D101 cannot be performed unless a high-frequency signal having a voltage amplitude equal to or higher than the threshold voltage of the diode D101 is input. Therefore, it is difficult to detect a low-power high-frequency signal with the circuit of FIG.

  By the way, until now, in mobile phones, which are representative of wireless communication devices, systems in which detailed information about output power is sent from the base station side, such as CDMA (Code Division Multiplexing), have been common. The output power of the high-frequency power amplifier used is often relatively large at about 30 dBm, and it was not necessary to accurately measure the low output power.

  However, in recent years, the spread of short-range wireless communication systems such as wireless LANs has begun.

  These systems have a relatively small maximum transmission power of about 20 dBm. Further, in order to prevent interference with other communication devices as much as possible or to reduce the power consumption of the terminal as much as possible, detailed power control over a wide range of transmission power has become necessary. For that purpose, it is necessary to accurately measure such low transmission power. Therefore, in the field of such short-range wireless communication, it is required that power detection be possible even with low transmission power.

  Therefore, FIG. 10 shows a circuit in which a bias voltage is applied to the diode D101 to enable detection of a low-power signal. FIG. 10 shows a circuit in which a bias circuit is added to the high-frequency power detection circuit of FIG. In this high frequency power detection circuit with a bias circuit, a resistor 104 and a transistor Tr103 are connected between a Vc terminal 104 to which a voltage Vc is applied and a ground. The transistor Tr103 is grounded at the emitter. A capacitor C103 is connected between the Vc terminal 104 and the ground. The base of the transistor Tr103 is connected to the capacitor C101 via the resistor R101. The connecting line 105 between the resistor R101 and the base is connected to the diode D101 via the resistor R103.

However, the high frequency power detection circuit of FIG. 10 requires an additional bias circuit, which increases the circuit scale and increases the chip area.
JP-A-4-207609

  SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor circuit, a semiconductor device, and a wireless communication device capable of detecting a low power signal with a simple and small-scale circuit.

In order to solve the above problems, a semiconductor circuit of the present invention includes a signal processing unit having a transistor and a detection circuit unit for detecting the output power of the transistor,
The detection circuit unit has at least a diode,
The base of the transistor and the diode are connected to at least one of a resistor and an inductor.

  In the semiconductor circuit of the present invention, the base of the transistor included in the signal processing unit and the diode included in the detection circuit unit are connected via at least one of a resistor or an inductor. Thereby, a voltage substantially equal to the base-emitter voltage of the transistor of the signal processing unit can be applied to the diode of the detection circuit unit. This makes it possible to apply a forward bias voltage in the vicinity of the threshold value of the diode to the diode of the detection circuit unit. Therefore, even when the input signal to the detection circuit unit is low output, a relatively large detection voltage can be extracted from the detection circuit unit.

  Thus, in the present invention, without providing a dedicated bias circuit as in the conventional example, at least one of a resistor or an inductor is provided at the base of the transistor of the signal processing unit used for signal amplification or the like. The forward bias voltage can be applied to the diode of the detection circuit section simply by adding the, and the circuit scale is hardly increased.

  When the bias voltage applied to the diode of the detection circuit unit is lower than the threshold voltage of the diode, the low power output from the signal processing unit cannot be detected. On the other hand, if the bias voltage greatly exceeds the threshold voltage of the diode, the offset of the detection voltage output from the detection circuit unit becomes large, so that there is a high possibility of generating an error particularly when performing low power detection. . Therefore, it is desirable that the bias voltage applied to the diode of the detection circuit unit is near the threshold voltage of the diode.

  Here, if the transistor of the signal processing unit is an amplifying transistor, the amplifying transistor is often operated at a bias point close to class B in order to increase power efficiency. In this case, the base potential of the amplifying transistor can be close to the threshold value of the diode of the detection circuit unit. Therefore, in this case, a bias near the threshold can be given to the diode of the detection circuit section relatively easily.

  In one embodiment, the base of the transistor and the diode are connected by a resistor.

  In this semiconductor circuit, for example, the bias voltage can be applied from the transistor of the signal processing unit to the diode of the detection circuit unit with only one resistor, and the circuit can be simplified most.

  In one embodiment, the base of the transistor and the diode are connected by an inductor.

  In this semiconductor circuit, since the base of the transistor of the signal processing unit and the diode of the detection circuit unit are connected by an inductor, the connection between the base of the transistor and the diode is opened at a high frequency. It is possible to prevent the high frequency signal from flowing into the detection circuit and to prevent the gain of the signal processing unit from deteriorating. Further, since the connection between the base of the transistor and the diode is short-circuited in a direct current manner, a higher detection voltage can be obtained from the detection circuit unit as compared with the case where the connection is performed by a resistor.

  In one embodiment of the semiconductor circuit, the base of the transistor and the diode are connected by a resistor and an inductor.

  In this semiconductor circuit, when the base of the transistor and the diode are connected by a series connection of the resistor and the inductor, the connection between the base of the transistor and the diode is opened at a high frequency. On the other hand, since the base of the transistor and the diode are connected only by a resistor in terms of direct current, the bias voltage to the diode of the detection circuit section can be adjusted by the resistance value of the resistor. In addition, when the base of the transistor and the diode are connected in parallel with the resistor and the inductor, the connection between the base of the transistor and the diode is short-circuited in terms of direct current. Compared with the case where only the resistor is used, a higher detection voltage can be obtained from the detection circuit unit.

  In one embodiment, the transistor and the diode are formed on the same substrate.

  In this semiconductor device, since the transistor and the diode are formed on the same substrate, further miniaturization can be achieved.

  In one embodiment, the transistor and the diode are formed of gallium arsenide bipolar elements.

  In this semiconductor device, the threshold voltage of the transistor and the diode can be made higher than when the transistor and the diode are made of other semiconductor materials. Therefore, a higher detection voltage can be obtained from the detection circuit unit.

  In one embodiment, a temperature compensation circuit that compensates for a change in the output of the transistor due to a temperature change is connected to the base of the transistor in the signal processing unit.

  In this semiconductor circuit, the temperature compensation circuit is connected to the base of the transistor of the signal processing unit, so that the output change of the transistor due to the temperature change is compensated, and the temperature compensation circuit is connected to the transistor of the signal processing unit and the detection circuit. It can also be used as a part of the diode. Therefore, the temperature compensation of the detection circuit unit can be realized without increasing the circuit scale, and a detection voltage stable with respect to a temperature change can be obtained.

  In one embodiment, the temperature compensation circuit includes a transistor or a diode.

  In this embodiment, if the transistor or diode included in the temperature compensation circuit is a transistor having the same structure as the transistor included in the signal processing unit or a diode having the same structure as the diode included in the detection circuit unit, a simple circuit is provided. With the configuration, temperature compensation of the signal processing unit and the detection circuit unit can be realized.

  In one embodiment, the transistor of the signal processing unit, the diode of the detection circuit unit, and the temperature compensation circuit are formed on the same substrate.

  According to this embodiment, since the transistor, the diode, and the temperature compensation circuit are formed on the same substrate, it is possible to detect a low power signal and obtain a stable detection voltage against a temperature change. Further reduction in size of the semiconductor device can be achieved.

  In one embodiment, the transistor of the signal processing unit, the diode of the detection circuit unit, and the temperature compensation circuit are formed of gallium arsenide bipolar elements.

  According to this embodiment, the threshold voltage of the transistor and the diode can be made higher than when the transistor and the diode are made of other semiconductor materials. Therefore, a higher detection voltage can be obtained from the detection circuit unit. Furthermore, the temperature compensation circuit can perform temperature compensation of the signal processing unit and the detection circuit unit.

  In addition, a wireless communication apparatus according to an embodiment includes the semiconductor circuit.

  According to this wireless communication apparatus, it is possible to realize a wireless communication apparatus capable of detecting a low power signal with a simple circuit scale. For example, if the semiconductor circuit is used in the final stage of a wireless communication device, low output power detection is possible, temperature stable detection is possible, and a detection circuit unit and a signal processing unit (power amplifier) There is a big effect such as making it possible to make it monolithic.

  According to the semiconductor circuit of the present invention, the base of the transistor of the signal processing unit is connected to the diode of the detection circuit unit by connecting the base of the transistor of the signal processing unit and the diode of the detection circuit unit via a resistor or inductor. -A voltage substantially equal to the emitter voltage is applied. As a result, a forward bias voltage in the vicinity of the threshold value of the diode can be applied to the diode of the detection circuit unit. Therefore, even when the input signal to the detection circuit unit is low output, a relatively large detection voltage can be extracted from the detection circuit unit.

  As described above, in the present invention, a dedicated bias circuit as in the conventional example is not provided, and only one resistor or inductor is added to the base of the transistor of the signal processing unit used for signal amplification or the like. Thus, a forward bias voltage can be applied to the diode of the detection circuit section, and the circuit scale is hardly increased. Therefore, it is possible to realize a semiconductor circuit capable of detecting a low power signal with a simple circuit scale.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First embodiment)
FIG. 1 shows a circuit of a semiconductor device as a first embodiment of the present invention. The semiconductor device according to the first embodiment includes a power amplification circuit 1 as a signal processing unit and a detection circuit unit 2 that detects an output of the power amplification circuit 1.

  In the power amplifier circuit 1, a capacitor C2 and a transistor Tr1 are connected in series between an input terminal 11 and an output terminal 12. The transistor Tr1 is a bipolar npn transistor, the emitter is connected to the ground, the base is connected to the capacitor C2, and the collector is connected to the output terminal 12. The transistor Tr1 may be a pnp transistor. The connection line 13 between the collector and the output terminal 12 is connected to the power supply voltage terminal 14 by the resistor R3 and is connected to the detection diode D1 of the detection circuit unit 2 by the capacitor C1. This power supply voltage terminal 14 is connected to a DC voltage source Vc.

  The connection line 15 between the base of the transistor Tr1 and the capacitor C2 is connected to the bias voltage terminal 16 and is connected to the detection diode D1 of the detection circuit unit 2 through the resistor R1. This bias voltage terminal 16 is connected to a DC voltage source Vb.

  The detection diode D1 included in the detection circuit unit 2 includes a transistor whose base and collector are short-circuited. The resistor R1 is connected to the anode (input side) of the detection diode D1, and the resistor R1 is connected to the base of the transistor Tr1. The capacitor C1 is connected to the anode (input side) of the detection diode D1, and the capacitor C1 is connected to the collector of the transistor Tr1.

  The cathode (output side) of the detection diode D1 is connected to the detection output terminal 17 by a connection line 18. A capacitor C3 and a resistor R2 are connected in parallel between the connection line 18 and the ground.

  Further, in the first embodiment, the circuit shown in FIG. 1, that is, the circuit constituted by the transistor Tr1, the detection diode D1, the capacitors C1, C2 and C3, and the resistors R1, R2 and R3 is a gallium arsenide semiconductor. It is integrally formed on the substrate.

  In the first embodiment, the detection diode D1 is a transistor having the same configuration as that of the transistor Tr1, with the base and collector short-circuited, with the base serving as the anode and the emitter serving as the cathode. In addition, the base of the transistor Tr1 and the detection diode D1 are connected via a resistor R1.

  In the first embodiment, when an input signal, which is a high frequency signal, is input to the input terminal 11 of the power amplifier circuit 1, this input signal is input to the base of the transistor Tr1, and the transistor Tr1 amplifies the input signal. The output signal is output from the collector. This output signal is output from the output terminal 12, and a part of the output signal is input to the detection diode D1 via the capacitor C1.

  Therefore, in this semiconductor device, an output signal obtained by amplifying the input signal input from the input terminal 11 to the power amplifier circuit 1 by the transistor Tr1 is output from the output terminal 12, and the output level of the output signal of the transistor Tr1 is set. The DC voltage, that is, the detection voltage Vsense can be taken out from the detection output terminal 17 of the detection circuit unit 2.

  In the semiconductor device of the first embodiment, since the anode of the diode D1 and the base of the transistor Tr1 are connected via the resistor R1, when the DC voltage Vb is applied to the bias voltage terminal 16, the diode D1 has the transistor Tr1 connected to the diode D1. A voltage almost equal to the base-emitter voltage is applied. In the semiconductor device of the first embodiment, since the diode D1 and the transistor Tr1 are formed on the same substrate, the on-voltage of the diode D1 is substantially equal to the base-emitter voltage of the transistor Tr1.

  For this reason, even when the high-frequency signal is not input to the detection circuit unit 2, the detection diode D1 is biased near the ON state. Therefore, even when a signal having a low power level is input from the capacitor C1 of the power amplifier circuit 1 to the detection diode D1 of the power detection circuit 2, the detection diode D1 operates and the detection output terminal of the detection circuit unit 2 is operated. The detection voltage Vsense can be taken out from 17.

  FIG. 2 shows a comparison between the output power dependence characteristic of the detection voltage Vsense in the first embodiment of FIG. 1 and the output power dependence characteristic of a circuit obtained by adding the conventional detection circuit (FIG. 9) to the power amplifier circuit 1. Here, the output power dependence characteristic is a characteristic in which the detection voltage Vsense depends on the power of the output signal of the power amplifier circuit 1. In FIG. 2, a characteristic S1 indicated by a solid line is an output power dependence characteristic in the first embodiment, and a characteristic S2 indicated by a broken line is an output power dependence characteristic in a conventional detection circuit.

  In the conventional detection circuit, the detection voltage cannot be taken out unless electric power equal to or higher than the threshold voltage of the diode is input to the detection circuit. In this example, as shown in the characteristic S2 of FIG. 2, the detection is performed only when the output power is 20 dBm or more. The voltage cannot be taken out.

  On the other hand, in the first embodiment, as indicated by the characteristic S1 in FIG. 2, the detection voltage Vsense can be extracted even when the power of the output signal input from the power amplifier circuit 1 to the detection circuit unit 2 is lower. I understand that. That is, the detected voltage changes according to the power of the output signal even when the power of the output signal is around 0 dBm.

  Note that there is an optimum value for the value of the resistor R1. That is, when the value of the resistor R1 is smaller than the optimum value by a predetermined value, a high-frequency input signal from the input terminal 11 to the transistor Tr1 of the power amplifier circuit 1 flows greatly into the detection circuit unit 2, and signal amplification Since the signal power input to the transistor Tr1 is reduced, the gain of the power amplifier circuit 1 is deteriorated, and the circuit characteristics are deteriorated.

  On the other hand, since the resistor R1 is a supply source of the detection voltage Vsense and a supply source of a direct current to the resistor R2, when the value of the resistor R1 is larger than the optimum value by a predetermined value, The current flowing through the resistor R1 is reduced, and the voltage applied to the input side of the detection diode D1 is reduced. Then, a sufficient detection voltage Vsense cannot be obtained from the detection circuit unit 2.

  Here, first consider the lower limit of the resistance value of the resistor R1. When the circuit of the first embodiment is considered in terms of high frequency, a transistor Tr1, a circuit composed of a diode D1, a resistor R1, and a capacitor C3 are connected in parallel to the input terminal 11. Therefore, if the input impedance of the circuit composed of the diode D1, the resistor R1, and the capacitor C3 is sufficiently larger than the input impedance of the transistor Tr1, it is considered that almost no current flows through the resistor R1 in terms of high frequency. It's okay.

  Assuming that the value of the power gain deterioration in the power amplifying circuit 1 is allowed to 1 dB due to the phenomenon of current flowing in the resistor R1, the impedance of the circuit composed of the diode D1, the resistor R1, and the capacitor C3 is the transistor Tr1. What is necessary is just 10 times or more of input impedance.

That is, assuming that the frequency is f, the input impedance of the transistor Tr1 is Zi1, the impedance of the diode D1 is Zi2 (= R _D + jX _D ), the resistance value of the resistor R1 is R1, and the capacitance of the capacitor C3 is C3. What is necessary is just to satisfy | fill Formula (1).

{(R1 + R _D ) ² + (X _D -1 / ωC3) ² } ^1/2 > A × | Zi1 | (1)
In equation (1), ω = 2πf, 10 <A
Next, consider the upper limit of the resistance value of the resistor R1. The resistor R1 serves as a current source that charges the capacitor C3. That is, when the resistance value of the resistor R1 increases, the current flowing through the resistor R1 decreases, the capacitor C3 cannot be charged sufficiently, and the detection voltage Vsense decreases. Therefore, in order to increase the detection voltage Vsense, it is desirable that the resistor R1 is small.

  From the above consideration, the optimum resistance value of the resistor R1 varies depending on the value of the element used in the circuit of this embodiment and the frequency used (that is, the frequency of the input signal).

Here, an example of the calculation of the resistance value of the resistor R1 is given. An input signal of 1.95 GHz is input from the input terminal 11 to the circuit of the first embodiment, the input impedance of the transistor Tr1 of this circuit is (5-j0.1) Ω, and the input impedance of the diode D1 is ( 10−j0.05) Ω, the capacitor C3 is 6.2 pF, and when A in the equation (1) is 100, the equation (1) is
[(R1 + 10) ² +
{0.05 + 1 / (2π × 1.95 × 10 ⁹ × 6.2 × 10 ⁻¹² )} ² ] ^1/2
> 100 × (5 ² +0.1 ² ) ^1/2 (2)
∴ R1> 489.9 (Ω)
Therefore, if the resistance value of the resistor R1 is about 500Ω or more, the above equation (2) is satisfied.

  Since the resistance value of the resistor R1 is desirably as small as possible from the viewpoint of the detection voltage, in the case of this calculation example, it can be said that the most suitable value for the resistance value of the resistor R1 is about 500Ω.

  Next, in FIG. 3, in this first embodiment, the dependence of the power gain of the power amplifier circuit 1 on the resistance value of the resistor R1 is shown by a characteristic S3 (solid line), and the detection circuit unit for the resistance value of the resistor R1 Dependency of the detection voltage Vsense of 2 is indicated by a characteristic S4 (broken line). These characteristics S3 and S4 are simulation results.

  Characteristics S3 and S4 shown in FIG. 3 are characteristics when the output power of the power amplifier circuit 1 is 20 dBm. As shown in FIG. 3, when the resistance value R1 of the resistor R1 becomes smaller than about 200Ω, the power gain and the detection voltage Vsense of the power amplifier circuit 1 are rapidly reduced. Further, when the resistance value of the resistor R1 becomes larger than about 200Ω, the detection voltage Vsense decreases. The characteristics of FIG. 3 are consistent with the above considerations. Therefore, the optimum value of the resistance value R1 of the resistor R1 may be determined by reading the desired power gain and detection voltage from the characteristics shown in FIG.

  For example, in the first embodiment, if the power gain is required to be 27 dBm or more and the detection voltage is required to be 0.5 V or more, the resistance value of the resistor R1 may be 200Ω or more and 1200Ω or less.

  In the first embodiment, the circuit is formed on the gallium arsenide substrate. However, the circuit may be formed on another compound semiconductor substrate, and the circuit may be formed on a substrate using another material such as silicon or gallium nitride. Even when formed, the above-described effects can be obtained. In particular, if a diode formed of a compound semiconductor such as gallium arsenide is used as the detection diode D1, the threshold voltage is high, so that a great effect can be expected to increase the detection voltage Vsense.

  By the way, a high-frequency circuit such as a power amplifier circuit is often formed on a compound semiconductor such as gallium arsenide, but a PN junction diode formed on a compound semiconductor such as gallium arsenide has a high threshold voltage of about 1.2V. For this reason, conventionally, it is difficult to detect a low-power signal, and thus a detection circuit for detecting the output signal of the power amplifier circuit is formed outside the chip.

  On the other hand, by adopting the detection circuit unit as in the first embodiment, the power amplifier circuit 1 and the detection circuit unit 2 can be formed on the same chip. Therefore, according to the first embodiment, the detection circuit unit 2 can be monolithically integrated with a high-frequency integrated circuit such as the power amplifier circuit 1, and there is a great effect of downsizing and improving reliability. Further, according to the first embodiment, it is possible to apply a forward bias voltage to the detection diode D1 by adding only one resistor R1 to the detection circuit unit 2 and hardly increasing the circuit scale. And the chip area is hardly increased.

  Further, it is known that when the output power of the amplifying transistor is small (that is, the input power is small), the base potential becomes large even if the bias voltage is constant (see Japanese Patent Laid-Open No. 9-260964). . Therefore, in this first embodiment, the lower the output power of the amplifying transistor Tr1, the higher the voltage biased to the detection diode D1, and the higher detection voltage Vsense can be obtained at low output power. Further, the higher the output power of the transistor Tr1, the smaller the voltage biased to the detection diode D1, so that the saturation of the detection voltage Vsense at the time of high output is suppressed and the dynamic range of detection is increased.

(Second Embodiment)
FIG. 4 is a circuit diagram of a semiconductor device according to the second embodiment of the present invention. As shown in FIG. 4, the second embodiment differs from the first embodiment only in that the resistor R1 in the first embodiment of FIG. 1 is replaced with an inductor L1.

  Therefore, in the second embodiment, the anode of the detection diode D1 of the detection circuit unit 2 and the base of the transistor Tr1 of the power amplifier circuit 1 are connected by the inductor L1.

  In the second embodiment, by replacing the resistor R1 with the inductor L1, the connection between the power amplifier circuit 1 and the detection circuit unit 2 is opened (opened) in terms of high frequency. Therefore, in the second embodiment, the input signal to the power amplifier circuit 1 does not flow greatly into the detection circuit unit 2, and the phenomenon that the gain of the power amplifier circuit 1 is not deteriorated does not occur.

  In addition, since the inductor L1 connecting the power amplifier circuit 1 and the detection circuit unit 2 is short-circuited in terms of DC, according to the second embodiment, the power is supplied by the resistor R1 as shown in FIG. Compared to the circuit in which the amplifier circuit 1 and the detection circuit unit 2 are connected, the amount of charge charged in the capacitor C3 is increased. Therefore, according to the second embodiment, a higher detection voltage Vsense can be obtained as compared with the first embodiment.

  FIG. 5 shows the result of comparison between the second embodiment of FIG. 4 and the first embodiment of FIG. 1 regarding the output power dependence characteristics of the detection voltage Vsense. The output power dependency characteristic is a characteristic in which the detection voltage Vsense depends on the power of the output signal of the power amplifier circuit 1. In FIG. 5, a characteristic S5 indicated by a solid line is an output power dependence characteristic of the second embodiment, and a characteristic S6 indicated by a broken line is an output power dependence characteristic of the first embodiment. Referring to FIG. 5, it can be seen that even with the same output power, the detection voltage Vsense can be higher in the second embodiment than in the first embodiment.

  As the inductor L1, it is desirable to use an inductor having an inductance value large enough to cut a high-frequency signal from the power amplifier circuit 1. For example, in the second embodiment, when the frequency of the input signal input from the input terminal 11 is 1.95 GHz, an inductor L1 of 50 nH or more may be used.

(Third embodiment)
Next, FIG. 6 shows a circuit of a semiconductor device according to the third embodiment of the present invention. The third embodiment is different from the first embodiment only in that a temperature compensation circuit 3 including a temperature compensation transistor Tr2 is connected to the power amplifier circuit 1.

  That is, in the third embodiment, the collector of the temperature compensating transistor Tr2 is connected to the connection line 21 that connects the connection line 15 connected to the base of the transistor Tr1 of the power amplifier circuit 1 to the bias voltage terminal 16. The temperature compensating transistor Tr2 has a base and a collector that are short-circuited and an emitter that is grounded. The temperature compensating transistor Tr2 and the capacitor C2 are connected in parallel to the base of the transistor Tr1. The temperature compensating transistor Tr2 and the detection diode D1 are connected in parallel to the base of the transistor Tr1.

  In the third embodiment, as described in the first embodiment, the transistor Tr1 and the detection diode D1 are composed of transistors having the same structure. Therefore, the temperature compensation circuit 3 including the temperature compensation transistor Tr2 can perform temperature compensation on the detection diode D1 as well as temperature compensation on the transistor Tr1. That is, the temperature compensation circuit 3 can be used as both the transistor Tr1 and the detection diode D1, and the temperature compensation circuit 3 compensates for an output change of the transistor Tr1 due to a temperature change, and at the same time, compensates the temperature compensation of the detection circuit unit 2. Can be realized. Therefore, temperature compensation of the detection circuit unit 2 can be realized without adding a new circuit and without causing an increase in circuit scale, and a detection voltage Vsense that is stable against temperature changes can be obtained. Therefore, since the bias circuit of the detection circuit unit 2 can be greatly simplified, the circuit scale can be greatly reduced.

  FIG. 7 shows a temperature dependence characteristic of the detection voltage Vsense in the third embodiment by a solid line characteristic S7. A broken line characteristic S8 indicates a temperature dependency characteristic of the detection voltage Vsense when the conventional detection circuit (FIG. 9) is connected to the power amplifier circuit 1. Referring to the characteristics S7 and S8 in FIG. 7, according to the third embodiment, the temperature dependence of the detection voltage Vsense is less than that of the conventional detection circuit, and the detection is relatively stable with respect to the temperature change. It can be seen that a voltage is obtained.

  In the third embodiment, the power amplifier circuit 1, the detection circuit unit 2, and the temperature compensation circuit 3 are formed on a gallium arsenide substrate, but may be formed on a substrate using other materials such as silicon or gallium nitride. Good. In the second embodiment described above, the temperature compensation circuit 3 may be provided as in the third embodiment, and in this case as well, the temperature dependence of the detection voltage Vsense can be reduced.

(Fourth embodiment)
Next, a fourth embodiment is shown in the block diagram of FIG. The fourth embodiment is an example of a wireless transmission device having a detection function, and is a transmitter having a detection function in a wireless LAN that handles a radio signal of 5 GHz.

  As shown in FIG. 8, the transmitter includes a power amplifier 24 having a detection function, an input control unit 25, and an A / D converter 26. The power amplifier 24 includes a power amplification unit 24A and a detection circuit unit 24B. In the fourth embodiment, the power amplifying unit 24A has the power amplifying circuit 1 described above in the final stage, and the detecting circuit unit 24B is composed of the detecting circuit unit 2 of the first or second embodiment.

  In the fourth embodiment, the transmission output detection signal S12 output from the detection circuit unit 24B of the power amplifier 24 is input to the A / D converter 26, and the transmission level is measured by the A / D converter 26. The A / D converter 26 outputs an input control signal S11 to the input control unit 25 when the measured transmission level varies by a predetermined amount with respect to a preset level. Then, the input control unit 25 controls the voltage level input to the power amplifier 24 and maintains the transmission output of the power amplifier 24 at a predetermined value.

  In the transmitter according to the fourth embodiment, since the semiconductor device according to the first or second embodiment is provided in the final stage of the power amplifier 24, detection at a low output level is possible, which is very useful. . If the semiconductor device of the third embodiment is used in the final stage of the power amplifier 24, detection at a low output level is possible and stable detection against temperature fluctuation is possible. Furthermore, since the power amplifier 24A and the detector circuit 24B of the power amplifier 24 can be formed on the same chip, monolithic chip can be realized.

  In the transmitter in the wireless LAN of 5 GHz according to the fourth embodiment, since the power amplifier 24 includes the detection circuit unit 24B, the transmission power can be controlled so as not to generate excessive transmission power. There is an effect that electric power can be achieved.

  In the fourth embodiment, an example of a method for processing a detection signal of a transmitter of a wireless LAN has been described. However, the detection signal processing method is not limited to this. The semiconductor circuit of the present invention can be used for other communication devices such as a transmitter of a portable terminal in addition to a transmitter of a wireless LAN of 5 GHz.

  In the first to third embodiments, the base of the transistor Tr1 and the diode D1 are connected by the resistor R1 or the inductor L1, but a resistor in which the base of the transistor Tr1 and the diode D1 are connected in series. The device R1 and the inductor L1 may be connected. In this case, the connection between the base of the transistor Tr1 and the diode D1 is opened in terms of high frequency. On the other hand, in terms of direct current, it is equivalent to the base of the transistor Tr1 and the diode D1 being connected only by the resistor R1, so the resistance value of the resistor R1 causes the diode D1 of the detection circuit section 2 to be connected to the diode D1. The bias voltage can be adjusted.

  Further, when the base of the transistor Tr1 and the diode D1 are connected by the parallel connection of the resistor R1 and the inductor L1, the connection between the base of the transistor Tr1 and the diode D1 is short-circuited in terms of DC. Therefore, a higher detection voltage Vsense can be obtained from the detection circuit unit 2 than in the case where the above connection is made only by the resistor R1.

1 is a circuit diagram of a semiconductor device according to a first embodiment of a semiconductor device of the present invention. It is a characteristic view which shows the comparison of the input power dependence of the detection voltage by the said 1st Embodiment and the detection voltage of the conventional detection circuit. It is a characteristic view which shows the dependence which the power gain and detection voltage in the said 1st Embodiment show with respect to the resistance value of resistor R1. It is a circuit diagram of the semiconductor device as 2nd Embodiment of this invention. It is a characteristic view showing the dependence which the detection voltage in 2nd Embodiment of this invention and the detection voltage in 1st Embodiment of this invention show with respect to output electric power. It is a circuit diagram of the semiconductor device of 3rd Embodiment of this invention. It is a characteristic view showing the dependence characteristic which the detection voltage in 3rd Embodiment of this invention and the detection voltage in 1st Embodiment of this invention show with respect to temperature. It is a block diagram of the radio transmitter which has a detection function of 4th Embodiment as a radio | wireless communication apparatus of this invention. It is a circuit diagram of the conventional output power detection circuit. FIG. 6 is a circuit diagram of another conventional output power detection circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power amplifier circuit 2 Detection circuit part 3 Temperature compensation circuit 11 Input terminal 12 Output terminal 14 Power supply voltage terminal 16 Bias voltage terminal 17 Detection output terminal 24 Power amplifier 25 Input control part 26 A / D converter Vd, Vc DC voltage source R1- R4 Resistor C1 to C3 Capacitor L1 Inductor D1 Detection Diode Tr1 Transistor Tr2 Temperature Compensation Transistor Tr103 Biasing Transistor Vsense Detection Voltage

Claims (8)

A signal processing unit having a transistor and a detection circuit unit for detecting the output power of the transistor;
The detection circuit unit has at least a diode,
A semiconductor circuit, wherein the base of the transistor and the diode are connected to at least one of a resistor and an inductor. A semiconductor circuit according to claim 1,
A semiconductor device, wherein the transistor and the diode are formed over the same substrate. A semiconductor circuit according to claim 1,
A semiconductor device, wherein the transistor and the diode are formed of a gallium arsenide bipolar element. The semiconductor circuit according to claim 1,
A semiconductor circuit, wherein a temperature compensation circuit for compensating for an output change of the transistor due to a temperature change is connected to a base of the transistor of the signal processing unit. The semiconductor circuit according to claim 4,
A semiconductor circuit, wherein the temperature compensation circuit includes a transistor or a diode. A semiconductor circuit according to claim 5,
The semiconductor device, wherein the transistor of the signal processing unit, the diode of the detection circuit unit, and the temperature compensation circuit are formed on the same substrate. A semiconductor circuit according to claim 5,
The semiconductor device, wherein the transistor of the signal processing unit, the diode of the detection circuit unit, and the temperature compensation circuit are formed of gallium arsenide bipolar elements.   A wireless communication device comprising the semiconductor circuit according to claim 1.

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