JP2003347864A - Transistor amplifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress performance variations in a transistor amplifier caused by variations in max output and distortion characteristics of a transistor element to obtain improved performance of the transistor amplifier such as multi- specification output, high efficiency, and low distortion. <P>SOLUTION: The amplifier for controlling an output level and a distortion level using the voltage value provided to a drain and a gate includes a detection method (branching filter) 11 for its output level, a drain voltage generation method 4 varying the drain voltage value so that the output level is higher than the predetermined level, a distortion detection method 7 detecting the distortion level of the amplifier from the input and output levels of the amplifier, and a gate voltage generation method 5 varying the gate voltage value so that the distortion level is minimized. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-output low-distortion transistor amplifier used for a digital mobile communication base station, for example.

[0002]

2. Description of the Related Art Conventionally, an amplifier of this type has been disclosed in
There are those disclosed in Japanese Patent Application Laid-Open No. 0-209770 and Japanese Patent Application Laid-Open No. H6-45993. These conventional techniques aim at obtaining the maximum power added efficiency by changing the drain (collector) voltage and the gate (base) voltage arbitrarily by variable control to change the saturation level of the transistor and the idle drain current. I have. Also, the one disclosed in Japanese Patent Application Laid-Open No. H10-215130 discloses that the output level is detected by a coupler and a detection circuit, and the saturation level of the transistor and the idle drain current are changed to obtain the maximum power added efficiency. ing.

[0003]

However, in actual operation of these conventional devices, it is difficult to obtain good distortion characteristics. Also, variations in the maximum output and distortion characteristics of the RF transistor elements during mass production have caused variations in the performance of the RF amplifiers used, thereby deteriorating the product yield.

[0004] The present invention has been made in view of the above points, and an object thereof is to improve the performance of an RF transistor amplifier, such as multi-specified output, high efficiency, and low distortion.

[0005]

SUMMARY OF THE INVENTION A transistor amplifier according to the present invention is an amplifier for controlling an output level and a distortion level by a voltage value supplied to a drain and a gate. Drain voltage generating means for varying the drain voltage value so that the output level is equal to or higher than a predetermined level; distortion detecting means for detecting the distortion level of the amplifier from the input level and the output level of the amplifier; And a gate voltage generating means for varying a gate voltage value.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 shows an RF transistor amplifier according to a first embodiment of the present invention. In the figure, 1 is an RF transistor, 1a is its drain (collector), 1b is its gate (base), 2b.
Is an input terminal of the amplifier, and 3 is an output terminal. 4 is a drain voltage generation circuit for supplying a voltage to the circuit of the drain 1a of the RF transistor 1, and 5 is a gate 1b of the RF transistor 1.
A gate voltage generating circuit 6 supplies a voltage to the above circuit, and a control circuit 6 controls output voltages of the drain voltage generating circuit 4 and the gate voltage generating circuit 5. Reference numeral 7 denotes a distortion level detection circuit that receives signals from the duplexers 9 and 10 connected to the input terminal 2 and the output terminal 3 of the amplifier, respectively, and detects the signals with the detection circuit 8. The output of the distortion level detecting circuit 7 and the output of the duplexer (output level detecting means) 11 connected to the output terminal 3 are given to the control circuit 6.

Next, the operation will be described with reference to FIGS. The RF maximum output value 20 of the RF transistor element 1 is
It is determined by the drain voltage value. On the other hand, R
The efficiency 21 of the F-transistor element 1 is expressed by the RF maximum output value 2
Back-off amount from 0 (difference between saturated output and operation output) 2
Determined by 2. Therefore, in the case where a different specified output is required or in the case of changing RF output power, it is necessary to always maintain the same back-off amount in order to always maintain the maximum efficiency. In order to maintain the minimum distortion level 23, it is necessary to optimize an idle drain current value (device operating point) that can be controlled by the gate voltage.

In the circuit shown in FIG. 1, a drain voltage variable function is added to the drain voltage generating circuit 4 of the RF transistor element 1, and a control circuit 6 is provided with a different RF specified output from the outside and a variable output terminal of the transistor 1. 3 is applied from the duplexer 11 to change the drain voltage of the drain voltage generating circuit 4 so that the maximum efficiency 21 is always obtained. At the same time, the distortion level is also detected by the distortion level detection circuit 7, and the output of the distortion level detection circuit 7 is used by the control circuit 6 by the gate voltage variable function of the gate voltage generation circuit 5 so that the minimum distortion level is obtained. The gate voltage is controlled for different RF regulation outputs and changing RF outputs.

As described above, for example, the RF of the RF transistor element 1 used in the final-stage amplifier of the multi-stage RF amplifier
Variations in the saturation output value and the distortion characteristics are absorbed by the drain voltage generation circuit 4 and the gate voltage generation circuit 5. As a result, variations in the performance of the multi-stage RF amplifier can be reduced.

Embodiment 2 FIG. 3 shows a second embodiment in which the present invention is applied to a feedforward amplifier. In the figure, 30 is a feedforward amplifier,
Reference numeral 31 denotes an input terminal, and 32 denotes an output terminal. 33 is a final stage amplifier, and 34 is an auxiliary amplifier.

The back-off amount of the pre-amplifier 35 is set aside so that the RF maximum output power and the distortion characteristic of the feed-forward amplifier 30 are determined by the final-stage amplifier 33. Since the power consumption of the pre-amplifier 35 is sufficiently smaller than that of the final-stage amplifier 33, a large back-off amount does not significantly affect the overall efficiency.

The power supply circuit 36 for the drain circuit 33a of the final-stage amplifier 33 includes a power supply circuit 37, a drain voltage variable circuit 38 and a drain voltage control circuit 39.
The power supply circuit 40 to the gate circuit 33b of the final-stage amplifier 33 includes a power supply circuit 41 and a gate voltage variable circuit 42.
And a gate voltage control circuit 43. The distortion level detection circuit 44 detects the distortion level from the splitter 45 at the preceding stage of the auxiliary amplifier 34, and controls the control circuits 39 and 43 with its output. 46 is a CPU, 47 is an external signal, and 48 is a power supply circuit of the preamplifier 35.

The feedforward amplifier 30 includes a
The control circuit has the RF specified output of 30 w and 30 w and has a drain voltage and a gate voltage determined to have the maximum efficiency and the minimum distortion in the trade-off between the distortion characteristics detected in advance. 39 and 43 are set in advance. The CPU 46 which has received the signal for switching the RF regulated output by the external signal 47 gives a command to the control circuits 39 and 43, and the control circuits 39 and 43 switch the set drain voltage and gate voltage. As a result, at each specified output,
Similar values of efficiency and distortion level are achieved.

Embodiment 3 FIG. 4 shows a third embodiment in which the present invention is applied to a feedforward amplifier. In the figure, components having the same functions as those in FIG. 3 of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 4, reference numeral 49 denotes a detection circuit connected to the duplexer 50 provided at the output terminal 32.

The back-off amount of the pre-amplifier 35 is reserved so that the RF maximum output power and the distortion characteristic of the feed-forward amplifier 30 are determined by the final-stage amplifier 33. Since the power consumption of the pre-amplifier 35 is sufficiently smaller than that of the final-stage amplifier 33, even if the back-off amount is increased, the overall efficiency is not significantly affected.

The power supply circuit 36 to the drain circuit 33a of the final-stage amplifier 33 includes a power supply circuit 37, a drain voltage variable circuit 38 and a drain voltage control circuit 39.
The power supply circuit 40 to the gate circuit 33b of the final-stage amplifier 33 includes a power supply circuit 41 and a gate voltage variable circuit 42.
And a gate voltage control circuit 43.

The feed-forward amplifier 30 has an arbitrary R
F output level, and information obtained by detecting an output signal split by a splitter 50 provided at an output end 32 by a detection circuit 49 so that maximum efficiency and minimum distortion characteristics can be obtained. From the information obtained by the level detection circuit 44, the control circuit 3 controls the drain voltage and the gate voltage so as to realize the state of the maximum efficiency and the low distortion characteristic.
9 and 43 are set in advance. As a result, maximum efficiency and minimum distortion level can be achieved at various output levels.

[0018]

As described above, according to the present invention, the variation in the performance of the transistor amplifier caused by the variation in the maximum output and the distortion characteristics of the transistor element during mass production is suppressed, the transistor amplifier has a multi-specified output, and the efficiency is high. Performance such as reduction in distortion and distortion can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram showing an RF transistor amplifier according to Embodiment 1 of the present invention.

FIG. 2 is a diagram illustrating the operation of the first embodiment.

FIG. 3 is a circuit configuration diagram showing an RF transistor amplifier according to a second embodiment of the present invention.

FIG. 4 is a circuit configuration diagram showing an RF transistor amplifier according to Embodiment 3 of the present invention.

[Explanation of symbols]

1 RF transistor, 1a drain, 1b gate, 2 input terminal, 3 output terminal, 4 drain voltage generation circuit, 5 gate voltage generation circuit,
6 control circuit, 7 distortion level detection circuit,
8 detection circuit, 9 demultiplexer,
10 splitter, 11 splitter,
30 feed forward amplifier, 31
Input end, 32 Output end, 33
Final stage amplifier, 33a drain circuit, 33b gate circuit, 34
Auxiliary amplifier, 35 pre-amplifier,
36 control circuit, 37 power supply circuit,
38 drain voltage variable circuit, 39 control circuit,
40 control circuit, 41 power supply circuit, 42 gate voltage variable circuit, 43 gate voltage control circuit, 44 distortion level detection circuit, 45 duplexer,
46 CPU, 47 external signal,
48 power supply circuit, 49 detection circuit,
50 branching circuit.

   ────────────────────────────────────────────────── ─── Continuation of front page    F term (reference) 5J091 AA04 AA41 AA58 CA21 CA36                       FA10 HA09 KA11 KA33 KA55                       KA68 MA14 MA20 MA22 SA13                 5J100 JA01 KA05 LA00 QA01 QA04                       SA01                 5J500 AA04 AA41 AA58 AC21 AC36                       AF10 AH09 AK11 AK33 AK55                       AK68 AM14 AM20 AM22 AS13

Claims (1)

[Claims] 1. An amplifier for controlling an output level and a distortion level by a voltage value supplied to a drain and a gate, comprising: an output level detecting means for the amplifier; and a drain voltage for controlling the output level to a predetermined level or more. Drain voltage generating means for varying the value, distortion detecting means for detecting the distortion level of the amplifier from the input level and output level of the amplifier, and gate voltage generating means for varying the gate voltage value such that the distortion level is minimized. A transistor amplifier comprising: