JP3411954B2 - Transistor amplifier - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transistor amplifier mainly used in a transmitting section of a mobile phone or the like and having a bipolar transistor using a compound semiconductor such as silicon or gallium arsenide as an amplifying element.

[0002]

2. Description of the Related Art GSM (Global System for Mobile), which is a European digital cellular system.
le Communications) is currently adopted in nearly 100 countries outside Europe, and has become the mainstream worldwide. The small size of mobile terminals such as mobile phones,
Although researches and developments for weight reduction have been vigorously carried out, if all the active components that make up a mobile terminal operate with a single positive power supply, a negative power supply or negative voltage generation circuit becomes unnecessary, and the terminal is small and lightweight. Silicon NPN that can operate with a single positive power supply as a power amplification device for transmission.
Bipolar transistors and gallium arsenide heterojunction bipolar transistors (hereinafter referred to as GaAs HBTs) can be promising devices in the future.

In particular, GaAs HBTs are superior to silicon bipolar transistors in high-frequency characteristics when operating at a low collector voltage, so that the number of battery cells is reduced and the power supply voltage of the terminals is reduced in order to reduce the size and weight of mobile terminals. It is expected as an important device that demonstrates its true value when it drops. In GSM, TDMA (T
image Division Multiple Acc
ess) system is adopted and transmission is performed with a burst waveform of 12.5% duty, but GMSK (Gaussian Mi), which is a kind of constant amplitude modulation, is used as a modulation system.
Since the Mimum Shift Keying) is adopted, the burst waveform is formed and the transmission power is controlled by controlling the gain of the transmission power amplifier with respect to an input signal having a constant amplitude.

As a first conventional circuit for forming a burst waveform as described above, a grounded-emitter power amplifier using a bipolar transistor is shown in FIG. 7, and a burst waveform forming method by gain control of the conventional circuit is shown in FIG. Show. Reference numeral 71 is a bipolar transistor, V ₁ is a first power source for gain control, and R ₁₁ is a base bias resistor of the bipolar transistor 71. When the base is biased by resistance division, the resistor Ra is necessary, and when the base current is biased by the resistance value of the bias resistor R ₁₁ , the resistor Ra may be omitted. An input signal of constant amplitude is input from the input terminal 72 to the base of the bipolar transistor 71, passes through the collector, and a burst waveform is output from the output terminal 73.

Since a burst waveform is formed from an input signal having a constant amplitude, as shown in FIG. 9, the output from the _first power supply V _{1 is set} to the minimum level V1min during the period of no transmission.
(Generally 0 to 0.5 V) to turn off the bipolar transistor 71.

An input signal of constant amplitude has constant power and
FIG. 9 shows a state in which an input signal having a constant value of electric power is input.

When the burst waveform is output, the burst waveform rises when the voltage from the _first power source V ₁ is V1min.
The gain of the transistor amplifier is changed until the output from the transistor amplifier reaches a predetermined power P ₀ (V = V1a). The output from the _first power supply V ₁ at this time is variable, and the maximum voltage V1max can be output. Further, the fall of the burst waveform forms a burst waveform by performing the procedure opposite to the rise of the burst waveform. The burst transmission period is from the time of rising from P _OFF to the time of falling from P ₀ , and one frame is a period from when the burst waveform starts to rise until the next burst waveform rises.

FIG. 8 shows a second conventional circuit of a grounded-emitter power amplifier using bipolar transistors. Reference numeral 81 is a first bipolar transistor for signal amplification, V ₁ is a first power source for gain control, V ₁
cc is a main power supply for the terminal, 82 is a second bipolar transistor that supplies the base current of the first bipolar transistor 81, and R ₂₁ is a base bias resistor of the second bipolar transistor 82. The first power supply V ₁ is usually lower in voltage than the main power supply Vcc of the terminal. If the base of the second bipolar transistor 82 is biased by resistance division, the resistor Rb is necessary, and if the base current is biased by the resistance value of the bias resistor R ₂₁ , the resistor Rb is not necessary. An input signal from the input terminal 83 is input to the base of the first bipolar transistor 81, and a burst waveform is output from the output terminal 84 through the collector. Although the circuit of the second conventional circuit is more complicated than that of the first conventional circuit, the base current of the first bipolar transistor 81 is supplied from the main power supply Vcc (for example, direct battery output) of the terminal. Power supply V ₁
The current to be supplied from the second bipolar transistor 8
The current gain can be reduced to _1/2 , and the load on the first power supply V ₁ can be reduced. The base of the first bipolar transistor may also have a resistor Rb for resistance division.

[0009]

However, due to the fact that an on-current of 0.7 V is required between the base and emitter of a bipolar transistor in the case of silicon and about 1.3 V in the case of GaAs HBT, There was a problem.

First, the problem will be described based on the first conventional circuit. The output voltage from the first power supply V ₁ is V1 (V1
<V1max: maximum output voltage), and the on-voltage between the base and emitter of the bipolar transistor is Von. Since the voltage drop due to the base current can be ignored until the bipolar transistor is turned on, if the base potential of the bipolar transistor 71 of the first conventional circuit is Vb1, then Vb1 = V1 (Equation 1).

The maximum voltage width Vw of the first power supply V ₁ for controlling the gain of the transistor amplifier can be expressed as Vw = V1max-Von (Equation 2) in the case of the first conventional circuit.

In the case of the second conventional circuit, the output voltage from the _first power source V _{1 for} gain control is V1 (V1 <V1max: maximum output voltage) until the bipolar transistor is turned on, and the second Assuming that the base potential Vb2 of the second bipolar transistor 82 of the conventional circuit is, Vb2 = V1 (Equation 3).

Further, the maximum voltage width Vw of the first power supply V ₁ for controlling the gain of the transistor amplifier is such that the base potential Vb2 of the bipolar transistor is equal to the base potential Vb2 of the bipolar transistors 81 and 82 which are connected in series. The bipolar transistors 81 and 82 are not turned on until Vb2 = 2Von (Equation 4) is reached, and Vw = V1max-2Von (Equation 5) is obtained.

At present, the power supply voltage of the battery of the portable terminal for digital transistor cellular such as GSM is 4.8V which is the serial connection structure of the nickel hydrogen battery 4 cells in the mainstream, but in order to further reduce the size and weight of the portable terminal. There is a strong demand for shifting the power supply voltage to 3.6 V, which is a configuration in which three cells of nickel-hydrogen battery are connected in series or a configuration of one cell of lithium ion battery.

As the power supply voltage drops, the first power supply V
_Although the maximum output voltage V1max from ₁ also decreases, since the ON voltage Von exists, the maximum voltage width Vw decreases more than the decrease rate of V1max as V1max decreases. The smaller the maximum voltage width Vw is, the smaller the minimum voltage V is from the non-output state to the predetermined output power P ₀ at the burst output.
The rate of change from 1 min to the voltage V1a must be set to a large value, and unless the output accuracy of the first power supply V ₁ is increased, the burst waveform formation accuracy decreases. In some cases, the waveform distortion at the rise or fall of the burst waveform also increases the risk of causing a fatal spurious at a level that deviates from the system standard. The problem is more serious in the case of the second conventional circuit than in the first conventional circuit, and more serious in the case of GaAs HBT than in the silicon bipolar transistor. Quasi-microwave or higher (800 for mobile communication)
In the frequency range of (MHz or more), GaAs HBT has a higher power added efficiency at low voltage operation than a silicon bipolar transistor, which greatly contributes to reduction of current consumption of mobile terminals and extension of talk time, thus solving the above problems. The significance is very great.

Therefore, it is an object of the present invention to provide a novel transistor amplifier capable of low voltage operation and low power consumption by solving the above problems.

[0017]

In order to solve the problem, the invention according to claim 1 is a transistor amplifier using a transistor for shaping a constant amplitude input signal into a burst waveform by gain control and outputting the burst waveform. A voltage supply means connected to the first power supply means, the voltage supply means switching the on / off state of voltage application in synchronization with the on / off state of the burst waveform. It is characterized by consisting of a power source and.

According to a second aspect of the present invention, in a transistor amplifier using a transistor for shaping a constant amplitude input signal into a burst waveform by gain control and outputting the burst waveform, a first transistor, a second transistor, and the second transistor. The emitter of the transistor is connected to the base of the first transistor, and the voltage supply means is connected to the base of the second transistor; the voltage supply means has a first power supply for gain control; and the burst. And a second power supply whose voltage application is switched between on and off states in synchronism with the on and off states of the waveform.

Further, in a transistor amplifier using a transistor for shaping a constant-amplitude input signal into a burst waveform by gain control and outputting the burst waveform according to claim 3, a gain control is applied to a first transistor and a base of the first transistor. A first power supply, a second transistor, an emitter of the second transistor connected to the base of the first transistor, and a voltage supply unit connected to the base of the second transistor; It is characterized in that the voltage supply means is composed of a second power supply whose on / off state of voltage application is switched in synchronization with the on / off state of the burst waveform.

Further, the first power source is connected via a first resistor, the second power source is connected via the second resistor, and the first power source outputs the lowest voltage, It is preferable that the first and second resistors are set such that the first and second transistors are of class B or class C when the second power source outputs a voltage.

Further, it is particularly effective when the first and second transistors are gallium arsenide compound heterojunction bipolar transistors.

[0022]

1 shows a transistor amplifier of the present invention as an embodiment, and FIG. 6 shows a method of forming a burst waveform.

In FIG. 1, 11 is a bipolar transistor. (Hereinafter, the bipolar transistor in the embodiments means a silicon bipolar transistor or GaAs.
It is HBT. ) V ₁ is a first power supply for controlling the gain of the transistor amplifier, V ₂ is a _second power supply whose on / off state is switched in synchronization with the burst signal, and through resistors R ₁₁ and R ₁₂ , respectively. It is connected to the base of the bipolar transistor 11. When the base is biased by resistance division, Ra may be omitted when the base current is biased by the resistance value of the resistor Ra. The signal is input to the base and output from the collector.

Since the input signal having a constant amplitude forms a burst waveform from the input terminal 12, as shown in FIG.
_The output power is suppressed by setting the output from ₁ to the minimum level V1min and minimizing the gain of the transistor amplifier. When the burst waveform is output from the output terminal 13, the first waveform of the first power source V _{1 is set} to V1 when the burst waveform rises.
Gradually increase from min, and the output is the specified power P
until a _o (V1 = V1a) to vary the gain of the transistor amplifier. At the fall of the burst waveform, the burst waveform is formed by performing the reverse procedure of the rise of the burst waveform.

The first power supply V for controlling the gain so that the first bipolar transistor 1 does not turn on when the burst waveform is output.
_In the voltage region of ₁ , the resistance value of the resistor R ₁₁ is R1, the resistance value of the resistor R ₁₂ is R2, and the voltage value of the second power supply V ₂ is V _2.
2, the base potential Vb1 of the first bipolar transistor 11 is Vb1 = V1 + R1 (V2-V1) / (R1 + R2) (Equation 6), which is ΔV = more than that of the first conventional circuit. R1 (V2-V1) / (R1 + R2) (Equation 7) is a high value, and the output voltage V1 from the _first power supply V1 can be made lower than that in the case of the first conventional circuit to turn on the transistor. Since it becomes possible, the maximum voltage width Vw can be expanded as compared with the first conventional circuit.

FIG. 10 is a diagram showing the relationship between the output voltage and the control voltage output from the first power supply V ₁ . In the first conventional circuit, the on-voltage is high, and therefore the curve rises sharply, whereas in the circuit of the present invention, the curve rises gently and the controllability is high.

Since the second power source is turned on only when the burst waveform is output and the second power source and the first transistor are turned off when the burst waveform is not output, no power is wasted when not outputting.

In this embodiment, the first power source V ₁ and the second power source V ₁
Is electrically connected to the power supply V _{2 of} the bipolar transistor via the first resistor R ₁ and the second resistor R ₂ , the base bias of the bipolar transistor is the first resistor R ₁₁ and the second resistor R 2. _It depends on the value of ₁₂ and the ratio of each resistance value.

Further, it is turned on in synchronization with the burst waveform output.
The second power supply V ₂ that turns off functions more effectively when the turning on timing of the second power supply V ₂ is at least earlier than the rising edge of the burst waveform and the turning off timing is at least later than the falling edge of the burst waveform. In that case, V1
b = V1min, and there is a period in which the second power supply V ₂ is in the ON state. If the transistor is turned on by the second power supply V ₂ during this period, the isolation of the transistor amplifier is not always good, and a signal exceeding the system standard may be output from the transistor amplifier during non-transmission.

In this case, the resistance values of the bias resistors R ₁₁ and R ₁₂ are set so that the transistors are of class B or class C when V1b = V1min and the second power source V ₂ is on. The isolation can be improved by suppressing the gain of the transistor amplifier.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention. Reference numeral 21 is the first for amplifying the input signal
Is a second bipolar transistor for supplying the base voltage of the first bipolar transistor 2, and Vcc is a main power supply for the terminal. V ₁ is a first power supply for gain control, V ₂ is a _second power supply whose on / off state is switched in synchronization with the burst signal, and the first bipolar power supply is provided through resistors R ₂₁ and R ₂₂ , respectively. It is connected to the base of the transistor 21. When biasing the base of the second bipolar transistor 22 by resistance division, the resistor Rb is necessary, and when biasing the base current depending on the resistance values of the resistors R ₁₁ and R ₁₂ , the resistor Rb is used.
b is not necessary.

An input signal is input from the input terminal 23 to the base of the first bipolar transistor 21, and a burst waveform is output from the output terminal 24 via the collector. The burst waveform forming method is the same as that of the first embodiment, but the maximum voltage width Vw can be expanded as compared with the second conventional circuit as in the first embodiment. Further, in the present embodiment, since a part of the base current to be supplied to the first bipolar transistor 21 can be supplied from Vcc, the current supplied from the first power supply V ₁ is reduced and the first power supply V ₁ is reduced. Load is reduced. First power supply V ₁ and second power supply V
₂ is electrically connected via the first and second resistors R ₂₁ and R ₂₂ , the second bipolar transistor 22
The base bias of is determined by the resistance values of the first and second resistors R ₂₁ and R ₂₂ , and the ratio of the two resistance values.

When a burst waveform is output from the output terminal 24,
In a voltage region where the second bipolar transistor 22 does not turn on, if the resistance value of the resistor R ₂₁ is R1, the resistance value of the resistor R ₂₂ is R2, and the voltage value of the second power supply V ₂ is V2, Base potential V of the bipolar transistor 22 of
b2 becomes Vb2 = V1 + R1 (V2-V1) / (R1 + R2) (Equation 8), and it becomes possible to turn on the transistor at a lower voltage than in the case of the second conventional circuit. Also, the maximum voltage width Vw can be expanded. Further, similarly to the invention of the first embodiment, the second power supply V ₂ is turned on only when the burst waveform is output, and is not output when the burst waveform is output.
_{Since the second} bipolar transistor 21 and the first bipolar transistor 21 are turned off, no power is wasted when no output is provided.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention. Reference numeral 31 is a first bipolar transistor for amplifying a signal, 32 is a second bipolar transistor for supplying a base current of the bipolar transistor 31, and Vcc is a main power supply for the terminal. V ₁ is a first power source for controlling the gain of the transistor amplifier, V ₂
Is a second power supply whose on / off state is switched in synchronization with the burst waveform. The first power supply is the bases of the first and second bipolar transistors 31 and 32 and the resistors R ₁₁ and R ₂₁ respectively. And a second power source connected to the first and second power sources.
Are connected to the bases of the bipolar transistors 31 and 32 via resistors R ₁₂ and R ₂₂ , respectively. When the bases of the first and second bipolar transistors 31 and 32 are biased by resistance division, the resistors Ra and Rb are required,
Ra may be omitted when the base current is biased by the resistance values of R ₁₁ , R ₁₂ , R ₂₁ , and R ₂₂ . Input terminal 33
To the base of the first bipolar transistor 31, the burst signal is output from the output terminal 34 through the collector. The burst waveform forming method is the same as that of the first embodiment, and like the first embodiment, the maximum voltage width Vw can be expanded relative to that of the second conventional circuit. In the second embodiment, the first bipolar transistor 31 does not turn on unless at least the second bipolar transistor 32 turns on, but in the third embodiment, the base of the first bipolar transistor 32 also has the resistance R _11. , R ₁₂ and biased by the first and second power supplies V ₁ and V ₂ , it is possible to further expand the maximum voltage width Vw as compared with the second embodiment. In the present embodiment, since a part of the base current to be supplied to the first bipolar transistor 31 can be supplied from Vcc, the current supplied from the first power supply V ₁ is reduced and the load of the first power supply V ₁ is reduced. Is reduced.

(Fourth Embodiment) FIG. 4 shows a fourth embodiment of the present invention. In FIG. 4, 41 is a first bipolar transistor for signal amplification, and 42 is a second bipolar transistor for supplying a base current of the first bipolar transistor 6.
, Vcc is the main power supply for the terminal. V ₁ is a first power supply for controlling the gain of the transistor amplifier, V ₂ is a _second power supply whose on / off state is switched in synchronization with the burst signal, and the first power supply is the first power supply.
Is connected to the base of the bipolar transistor 41 via a resistor R ₁₁ , and the second power supply V ₂ is connected to the bases of the first and second bipolar transistors 41 and 42 via resistors R ₁₂ and R ₂₂ , respectively. To be done. When the bases of the first and second bipolar transistors 41 and 42 are biased by resistance division, the resistors Ra and Rb are required,
If the base current is biased by the resistance values of R ₁₁ , R ₁₂ , and R ₂₂ , Ra and Rb may be omitted. Input terminal 43
Is input to the base of the first bipolar transistor 41, and a burst waveform is output from the output terminal 44 through the collector. The gain control of the transistor amplifier is performed by controlling the base voltage of the first bipolar transistor 41 by the first power supply V ₁ .
The burst waveform forming method is the same as that of the first embodiment, and like the first embodiment, the maximum voltage width Vw can be expanded compared to the first conventional circuit. In the present embodiment, since a part of the base current to be supplied to the first bipolar transistor 41 can be supplied from Vcc, the current supplied from the first power supply V ₁ is reduced and the load of the first power supply V ₁ is reduced. Is reduced.

(Fifth Embodiment) The fifth embodiment of the present invention
The state is shown in FIG. In FIG. 5, reference numeral 51 denotes a first signal amplifying unit.
Bipolar transistor, 52 is the first bipolar transistor
Second bipolar for supplying base current of transistor 51
The transistor, Vcc, is the main power supply for the terminal. V₁Is
A first power source for controlling the gain of the transistor amplifier, V₂Is
The on / off state turns off in synchronization with the burst waveform output.
It is the second power source to be replaced. First power source V ₁Is the first bar
Base of Ipolara transistor 51 and resistor R₁₁Through
Connected by the second power source V₂Is the second bipolar transistor
Base of resistor 52 and resistor R_{twenty two}Connected via.
First and second bipolar transistors by resistance division
When biasing the bases of 51 and 52, resistors Ra and R are used.
b is required, R₁₁, R_{twenty two}Depending on the resistance value of the base
Ra and Rb may be omitted when biasing the flow. Entering
The input signal from the input terminal 53 is the second bipolar transistor.
Input to the base of the data 52 and output terminal via the collector
A burst waveform is output from 54. Transistor amplification
The gain control of the device is based on the first power supply V₁By the first bipo
By controlling the base voltage of the error transistor 51.
The burst waveform forming method is the same as that of the first embodiment.
It is the same as the state. In the present embodiment, the second power source V₂Effect of
The result is the base-emitter charge of the bipolar transistor 52.
The voltage drop corresponding to the voltage Von is partially offset, so the fourth
Although not as effective as the first embodiment,
Similarly, it is possible to expand Vw relative to the first conventional circuit.
In addition, the circuit is simpler than that of the fourth embodiment.
Be done. Also in this embodiment, the first bipolar transistor is also used.
Whether a part of the base current to be supplied to the transistor 51 is Vcc
Can be supplied from the first power source V₁The current supplied from
The gain control power supply is reduced compared to the first conventional circuit.
1 power supply V₁Load is reduced.

[0037]

According to the present invention, low voltage operation is possible,
A novel transistor amplifier with low power consumption can be provided. Further, it is possible to provide a power transistor amplifier using a bipolar transistor having a gradual change in gain with respect to a control voltage and having high controllability.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a transistor amplifier of the present invention.

FIG. 2 is a circuit diagram of a transistor amplifier of the present invention.

FIG. 3 is a circuit diagram of a transistor amplifier of the present invention.

FIG. 4 is a circuit diagram of a transistor amplifier of the present invention.

FIG. 5 is a circuit diagram of a transistor amplifier of the present invention.

FIG. 6 is a diagram showing a burst waveform forming method according to the present invention.

FIG. 7 is a circuit diagram of a conventional transistor amplifier.

FIG. 8 is a circuit diagram of a conventional transistor amplifier.

FIG. 9 is a diagram showing a conventional method of forming a burst waveform.

FIG. 10 is a diagram showing a relationship between an output voltage and a control voltage.

[Explanation of symbols]

11, 21, 31, 41, 51 First bipolar transistor 22, 32, 42, 52 Second bipolar transistor 12, 23, 33, 43, 53 Input terminal 13, 24, 34, 44, 54 Output terminal R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , Ra, Rb Resistance V ₁ First power supply V ₂ Second power supply Vcc Main power supply

Claims (5)

(57) [Claims] 1. A transistor amplifier using a transistor for shaping a constant amplitude input signal into a burst waveform by gain control and outputting the burst waveform, comprising: voltage supply means connected to the base of the transistor, wherein the voltage supply means comprises: A transistor amplifier comprising: a first power supply for controlling gain; and a second power supply whose on / off state of voltage application is switched in synchronization with the on / off state of the burst waveform. 2. A transistor amplifier using a transistor for shaping a constant amplitude input signal into a burst waveform by gain control and outputting the burst waveform, wherein a first transistor, a second transistor, and an emitter of the second transistor are the A voltage supply means connected to the base of the first transistor and connected to the base of the second transistor; a first power supply for performing gain control by the voltage supply means; and an on / off state of the burst waveform And a second power supply whose voltage application is switched between on and off states in synchronization with the transistor amplifier. 3. A transistor amplifier using a transistor for shaping a constant amplitude input signal into a burst waveform by gain control and outputting the burst waveform, wherein the first transistor and the base of the first transistor control the gain.
Of the power supply, the second transistor, the emitter of the second transistor is connected to the base of the first transistor, the voltage supply means connected to the base of the second transistor, and the voltage supply means. A second power supply that switches the on / off state of voltage application in synchronization with the on / off state of the burst waveform. 4. The first power source is connected via a first resistor, the second power source is connected via the second resistor, and the first power source outputs a minimum voltage, The first and second resistors are set such that the first and second transistors are of class B or class C when the second power source outputs a voltage. 4. The transistor amplifier according to any one of 1 to 3. 5. The transistor amplifier according to claim 1, wherein the first and second transistors are gallium arsenide compound heterojunction bipolar transistors.