JP2012023583A - Differential amplification circuit, regulator module, and high power amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a regulator module that excels in a manufacturing process and power consumption of products and a bias circuit using the same.SOLUTION: A technique for mounting a bipolar transistor and a field-effect transistor on the same substrate enables a power amplifier including a power amplifier module and a regulator module 801 to be configured with one chip. The regulator module 801 includes a differential amplification circuit by a depletion-type transistor. Connecting one FETQ4 source terminal of the differential amplification circuit to an FETQ3 source terminal via a diode-connected bipolar transistor Q7 enables the potential difference of the bipolar transistor Q7 to be used as an output voltage of an regulator.

Description

  The present invention relates to a power amplifier used in a mobile phone device and the like, and more particularly to a regulator module and a power amplifier module in the power amplifier.

  Mobile phones of third generation specifications (generally W-CDMA and CDMA2000) are already widely used worldwide. A power amplifier is indispensable for this third generation mobile phone. In these specifications, even a single specification is required to support a plurality of frequency bands. For example, in the W-CDMA specification, it is almost essential in the current market to support 800 MHz, 2.0 GHz, and the like. Further, in the second generation specification (GSM or the like), different frequency bands may be allocated.

  For the correspondence to the plurality of frequency bands, the designer selects whether to use a power amplifier that is compatible with a plurality of bands or a plurality of systems, or a plurality of single mode power amplifiers.

  When a single mode power amplifier is used, there is a strong demand for small size and low price. From this point of view, a single-chip power amplifier is desirable when configuring a single mode power amplifier. However, conventionally, it is composed of two chips, a power amplifier module using an HBT process having excellent high frequency characteristics and a voltage regulator module using a MOSFET process for supplying a bias voltage.

  FIG. 1 is a circuit diagram showing a configuration of a conventional single mode power amplifier. This conventional single mode power amplifier (power amplifier) includes a regulator module 801 and a power amplifier module 802.

  The power amplifier module 802 has a diode-connected two-stage structure. In the HBT process used by the power amplifier module 802, the output voltage of the regulator module 801 requires 2.8V or more.

  On the other hand, the regulator module 801 has a MOSFET in the output stage. When the drain-source voltage of this MOSFET is 0.3V, the minimum operating power supply voltage required by this conventional regulator module 801 is about 3.1V.

  Since this conventional single mode power amplifier has a two-chip configuration, there is a limit to miniaturization, and price competitiveness also decreases.

  Further, since the minimum operating power supply voltage is 3.1 V, it cannot be applied to a device oriented to low voltage driving.

  Further, the output voltage 2.8V of the regulator module 801 is randomly varied for each product. Due to this variation, the conventional power amplifier module 802 has gain sensitivity. The reason for this variation is that the deviation from the band gap voltage of 1.23 V is amplified by a non-inverting amplifier about 2.3 times and output. If this deviation exceeds a predetermined value, it will be difficult to handle as a product, resulting in a decrease in yield.

  Further, the conventional regulator module 801 is composed of an enhancement MOS. Therefore, a 1.23V output of a voltage generation circuit 801a such as a band gap circuit is required as a reference for the differential amplifier 801b. The voltage generation circuit 801a increases the circuit scale of the regulator module 801.

  In Japanese Patent Laid-Open No. 2002-344259 (Patent Document 1), as a countermeasure against an increase in the circuit scale of the regulator module 801, a differential amplifier circuit is configured using a depletion type transistor and an enhancement type transistor, and a difference in threshold value is calculated. It is described that an increase in chip size is prevented by using an internal reference voltage.

JP 2002-344259 A

  However, to change the threshold value, it is necessary to change the implantation concentration on the channel surface. Since the formation of the depletion type transistor and the enhancement type transistor is a separate process, a difference in threshold variation and a difference in internal reference voltage are generated independently for each product.

  An object of the present invention is to provide a regulator module that is excellent in terms of manufacturing processes and power consumption of a product, and a bias circuit using the regulator module.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  A differential amplifier circuit according to a representative embodiment of the present invention includes a first depletion type FET, a second depletion type FET, a third depletion type FET, and a base terminal and a collector terminal connected to each other. A source terminal and a gate terminal of the third depletion type FET, and a gate terminal of the first depletion type FET is grounded, and a drain terminal of the third depletion type FET is the first depletion type FET. And the source terminal of the second depletion type FET are connected to the collector terminal and the base terminal of the bipolar transistor.

  By using the regulator module according to the present invention, the regulator module and the power amplifier module can be made into a one-chip MMIC (monolithic microwave integrated circuit).

  Further, by using the regulator module according to the present invention, a bandgap voltage generation circuit becomes unnecessary, and the circuit scale can be reduced.

  Further, by using the regulator module according to the present invention, the driving voltage can be made less than 3 V, and driving by a lithium ion battery is also possible.

It is a circuit diagram showing the structure of the conventional single mode power amplifier. It is a circuit diagram of the regulator module in connection with the 1st Embodiment of this invention. It is a conceptual diagram showing the difference of the operation area | region of a depletion type transistor and an enhancement type transistor. It is a circuit diagram of another regulator module in connection with the 1st Embodiment of this invention. It is a circuit diagram of another regulator module in connection with the 1st Embodiment of this invention. It is a circuit diagram of another regulator module in connection with the 1st Embodiment of this invention. It is a circuit diagram of the regulator module in connection with the 2nd Embodiment of this invention. It is a circuit diagram of another regulator module in connection with the 2nd Embodiment of this invention. It is a circuit diagram at the time of using the regulator module concerning this invention by HPA. It is a circuit diagram at the time of using the regulator module concerning this invention with another HPA.

  In the following embodiment, when it is necessary for the sake of convenience, the description will be divided into a plurality of sections or embodiments. However, unless otherwise specified, it is not irrelevant to one another, and one is related to some or all of the other, details, supplementary explanations, and the like. Also, in the following embodiments, when referring to the number of elements (including the number, numerical value, quantity, range, etc.), especially when clearly indicated and when clearly limited to a specific number in principle, etc. Except for the specific number, the number may be more than or less than the specified number.

  Further, in the following embodiments, it is needless to say that the constituent elements are not necessarily essential unless particularly specified and apparently essential in principle. Note that in the embodiment, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor: abbreviated as a MOSFET transistor) does not exclude a non-oxide film as a gate insulating film.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 2 is a circuit diagram of the regulator module according to the first embodiment of the present invention. This embodiment will be described with reference to this figure.

  This regulator module includes active loads Q1, Q2, FETs Q3, Q4, a constant current source Q5, an FET Q6, a bipolar transistor Q7, and a resistor R1. All elements other than the bipolar transistor Q7 are constituted by depletion type transistors.

  The active loads Q1 and Q2 are FET resistors that serve as loads when the power supply voltage VDD is input to the FETs Q3 and Q4. By short-circuiting the gate-source terminals of the active loads Q1, Q2, these FETs function as resistors.

  The constant current source Q5 is a constant current source for setting the source terminal of the FET Q3 and the emitter terminal of the bipolar transistor Q7 to the same potential.

  The bipolar transistor Q7 adopts an NPN type configuration. The bipolar transistor Q7 is diode-connected by short-circuiting the collector and base. Due to the presence of the bipolar transistor Q7, the source terminal of the FET Q4 is higher than the source terminal of the FET Q3 by the base-emitter voltage Vbe of the bipolar transistor Q7 (for example, about 1.3 V in the case of GaAs HBT).

  The FETs Q3 and Q4 and the bipolar transistor Q7 have a differential amplifier configuration.

  FIG. 3 is a conceptual diagram showing a difference in operation region between the depletion type transistor and the enhancement type transistor. This diagram is merely a conceptual diagram, and FIG. 3 is not an accurate graph.

  As is clear from this figure, in the depletion type transistor, even when the gate-source voltage (relative voltage of the gate terminal as viewed from the source terminal) is 0 V, a current can flow through the drain terminal. The FET Q3 uses this.

  The gate terminal of the FET Q3 is grounded. On the other hand, the source terminal is grounded via a constant current source Q5. Therefore, even when the gate-source voltage Vgs is 0 V, the FET Q3 operates without any problem.

  The FET Q4 is a depletion type transistor as well as the FET Q3. The gate terminal of the FET Q4 is grounded via the resistor R1. Further, the potential of the source terminal of the FET Q4 is also higher than the potential of the source terminal of the FET Q3 because the potential is supplied through the bipolar transistor Q7 in addition to the constant current source Q5.

  As described above, since the potential of both the source terminal and the gate terminal of the FET Q4 is higher than the corresponding terminal of the FET Q3, as a result, the gate-source voltage Vgs is substantially the same for both the FET Q3 and the FET Q4. Note that the gate terminal of the FET Q3 is grounded, and the source terminal of the FET Q3 is substantially the same as the ground potential. For this reason, when outputting from the FET Q4 side, the output of the differential amplifier can be made high by the base-emitter voltage Vbe of the bipolar transistor Q7.

  The FET Q6 is a grounded drain circuit that inputs the output voltage of the differential amplifier circuit composed of the FET Q3 and the FET Q4 (the voltage at the drain terminal of the FET Q4) to the gate and outputs the voltage from the source terminal. The FET Q6 functions as an output transistor. This output voltage is fed back to the gate terminal of the FET Q4, whereby the gate-source voltage of the FET Q4 changes.

  The output voltage of the FET Q6 becomes the output of the regulator module and is fed back to the FET Q4. As a result, the output voltage can be kept constant, that is, the base-emitter voltage Vbe of the bipolar transistor Q7.

  By configuring as described above, the following advantages can be obtained.

  In the above circuit, a differential amplifier is formed using the base-emitter voltage Vbe (1.3 V) of the bipolar transistor Q7 as a reference voltage. The regulator module including the bipolar transistor Q7 can be formed by a process in which the bipolar transistor and the field effect transistor are provided on the same substrate. Therefore, when using a power amplifier module using a bipolar transistor as an amplifying element and this regulator module, the power amplifier module and the regulator module can be formed on the same substrate. That is, since the bipolar transistor of the regulator module and the bipolar transistor of the power amplifier module are formed on the same substrate, it is possible to cancel the temperature dependence of the base-emitter voltage and the element variation.

  In the bipolar transistor, the threshold variation of the base-emitter voltage is about several tens of mV. Therefore, the output voltage deviation can be kept small.

  In addition, the above-described circuit can be made into a single chip by creating a process (for example, BIFET) in which the bipolar transistor and the field effect transistor are provided on the same substrate.

  It should be noted that the normally considered changes are included in the range of the present embodiment. FIG. 4 to FIG. 6 are diagrams for enumerating modifications of the first embodiment.

  FIG. 4 is a circuit diagram of another regulator module according to the first embodiment of the present invention. In this example, a FET Q8 is inserted instead of the resistor R1.

  FIG. 5 is a circuit diagram of another regulator module according to the first embodiment of the present invention. In this example, the FET Q6 is replaced with a bipolar transistor Q6b.

  FIG. 6 is a circuit diagram of still another regulator module according to the first embodiment of the present invention. In the circuit of this figure, both the correspondence of FIG. 4 and FIG. 5 is performed.

  Modifications that divert these general techniques are naturally included in the range of the present invention.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to the drawings.

    FIG. 7 is a circuit diagram of a regulator module according to the second embodiment of the present invention.

  Instead of the resistor R1 of the regulator module of FIG. 2, the regulator module of FIG. 7 is characterized in that a voltage dividing circuit DIV composed of a resistor R11 and a resistor R12 is inserted. By inserting the voltage dividing circuit DIV, the voltage dividing circuit DIV including the resistors R11 and R12 divides the output voltage of the FET Q6. The divided potential is fed back to the FET Q4.

  By doing so, the output voltage of the regulator module (= the output voltage of the FET Q6) can be set to (R11 + R12) / R12 of the base-emitter voltage of the bipolar transistor Q7. Thus, the regulator module of the present embodiment has the function of the differential amplifier 801b in FIG.

  In the present embodiment as well, the FET Q6 can be replaced with the bipolar transistor Q6b, as in the first embodiment. This replacement is shown in FIG. FIG. 8 is a circuit diagram of another regulator module according to the second embodiment of the present invention.

(Third embodiment)
Next, a third embodiment of the present invention will be described. The third embodiment is an application example on how to actually use the regulator module of the first embodiment and the second embodiment.

  This embodiment shows how to use the regulator module described above in a high power amplifier (HPA).

  FIG. 9 is a circuit diagram when the regulator module according to the present invention is used in HPA.

  This HPA employs a configuration in which the RF input signal is amplified twice. At this time, the former stage is called a driver stage, and the latter stage is called a power stage. A regulator module according to the present invention is connected to each stage as a bias module. In the figure, these bias modules are surrounded by broken lines. In this figure, the power supply voltage VDD of the regulator module is 2.3V. In the figure, the power supply voltage VDD is omitted and only “2.3 V” is described.

  The RF input signal input from the RF signal terminal is input to the driver stage via the input matching circuit. At this time, the bias voltage of the power amplifier module 802-1 in the driver stage is set by the output of the regulator module 801-1.

  The same applies to the power stage. The output of the driver stage is input to the power stage via the interstage matching circuit. At this time, the bias voltage of the power amplifier module 802-2 in the power stage is set by the output of the regulator module 801-2.

  As described above, the output of the regulator module of FIG. 2 according to the first embodiment is substantially the same as the base-emitter voltage Vbe of the bipolar transistor Q7. If the regulator module shown in FIG. 7 is used instead of the regulator module shown in FIG. 2, the bias voltage can be increased.

  FIG. 10 is a circuit diagram when the regulator module according to the present invention is used in another HPA. Here, the regulator module of FIG. 7 is used, but of course, the regulator module of FIG. 2 also operates.

  In the configuration of FIG. 10, a wideler type current mirror is provided outside the regulator module. As a result, the base current of each stage is controlled to enable highly accurate bias setting.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

  In particular, compound semiconductors such as GaAs are generally accompanied by difficulties in processing and a decrease in electrical characteristics in order to make the FET perform an enhancement operation. Further, since the mobility of GaAs holes is low, the P-type FET is not practical. Therefore, when the technique of the present invention is realized with a compound semiconductor such as GaAs, it is not necessary to use an enhancement type or P type FET, and therefore, the effect is greater than when it is formed on a silicon substrate.

801, 801-1, 801-2 ... regulator module,
801a: voltage generation circuit, 801b: differential amplifier,
802, 802-1, 802-2 ... Power amplifier modules.

Claims (16)

A differential amplification circuit including a first depletion type FET, a second depletion type FET, a third depletion type FET, and a bipolar transistor having a base terminal and a collector terminal connected thereto,
The source terminal and gate terminal of the third depletion type FET and the gate terminal of the first depletion type FET are grounded,
The drain terminal of the third depletion type FET is connected to the source terminal of the first depletion type FET and the emitter terminal of the bipolar transistor,
A differential amplifier circuit, wherein a source terminal of the second depletion type FET is connected to a collector terminal and a base terminal of the bipolar transistor.   2. The differential amplifier circuit according to claim 1, wherein the drain terminal of the first depletion type FET and the drain terminal of the second depletion type FET are separately connected to an active load connected to a power source. A differential amplifier circuit.   3. The differential amplifier circuit according to claim 1, wherein the differential amplifier circuit is configured by a technique in which a bipolar transistor and a field effect transistor are provided on the same substrate. A regulator module that differentially amplifies the first depletion type FET and the second depletion type FET, and the third depletion type FET functions as an output transistor,
The gate terminal of the first depletion type FET is grounded,
A regulator module, wherein an output voltage of a source terminal of the third depletion type FET is fed back to a gate terminal of the second depletion type FET. The regulator module according to claim 4, further comprising a diode-connected bipolar transistor,
The collector terminal and base terminal of the bipolar transistor are connected to the source terminal of the second depletion type FET,
A regulator module characterized in that an emitter terminal of the bipolar transistor and a source terminal of the first depletion type FET have the same potential.   5. The regulator module according to claim 4, wherein an output voltage of the source terminal of the third depletion type FET is divided and then fed back by being input to the gate terminal of the second depletion type FET. Regulator module to be used.   5. The regulator module according to claim 4, wherein an output of a source terminal of the third depletion type FET becomes an output of the regulator module.   8. The regulator module according to claim 7, wherein an output of the regulator module is connected to a power amplifier module.   9. The regulator module according to claim 8, wherein the regulator module is constituted by a technique in which a bipolar transistor and a field effect transistor are provided on the same substrate as the power amplifier module on the same chip. A high power amplifier that amplifies power by a power amplifier module that uses a DC component output from the regulator module as a bias,
The regulator module includes a differential amplifier circuit including a first depletion type FET, a second depletion type FET, a third depletion type FET, and a diode-connected bipolar transistor;
The source terminal and gate terminal of the third depletion type FET and the gate terminal of the first depletion type FET are grounded,
The drain terminal of the third depletion type FET is connected to the source terminal of the first depletion type FET and the emitter terminal of the bipolar transistor,
A high power amplifier characterized in that a source terminal of the second depletion type FET is connected to a collector terminal and a base terminal of the bipolar transistor.   11. The high power amplifier according to claim 10, wherein the source terminal voltage of the third depletion type FET uses the DC component as a bias.   12. The high power amplifier according to claim 10, wherein the high power amplifier is constituted by a technique in which a bipolar transistor and a field effect transistor are provided on the same substrate. A high power amplifier including a regulator module and a power amplifier module,
A high power amplifier, wherein the regulator module and the power amplifier module are configured on a single chip by a technique in which a bipolar transistor and a field effect transistor are provided on the same substrate. 14. The high power amplifier according to claim 13, wherein the regulator module includes a differential amplifier circuit including two or more FETs having a first FET and a second FET,
The source terminal of the first FET is connected to a predetermined potential,
The source terminal of the second FET is connected to the predetermined potential via the diode-connected bipolar transistor,
A high power amplifier, wherein an output voltage to the power amplifier module is driven by a drain terminal voltage of the second FET.   15. The high power amplifier according to claim 14, wherein an output voltage to the power amplifier module is fed back to a gate terminal of the second FET.   15. The high power amplifier according to claim 14, wherein the output voltage to the power amplifier module is divided and fed back to the gate terminal of the second FET.

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