GB2310330A - Determining power control function for transmitter amplifier - Google Patents
Determining power control function for transmitter amplifier Download PDFInfo
- Publication number
- GB2310330A GB2310330A GB9603185A GB9603185A GB2310330A GB 2310330 A GB2310330 A GB 2310330A GB 9603185 A GB9603185 A GB 9603185A GB 9603185 A GB9603185 A GB 9603185A GB 2310330 A GB2310330 A GB 2310330A
- Authority
- GB
- United Kingdom
- Prior art keywords
- power control
- power
- microprocessor
- circuit
- amplifier circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
- H03G3/001—Digital control of analog signals
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03G—CONTROL OF AMPLIFICATION
- H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
- H03G3/20—Automatic control
- H03G3/30—Automatic control in amplifiers having semiconductor devices
- H03G3/3036—Automatic control in amplifiers having semiconductor devices in high-frequency amplifiers or in frequency-changers
- H03G3/3042—Automatic control in amplifiers having semiconductor devices in high-frequency amplifiers or in frequency-changers in modulators, frequency-changers, transmitters or power amplifiers
Description
AMPLIFYING CIRCUIT AND METHOD FOR DETERMINING AND
PROGRAMMING POWER CONTROL LEVELS THEREIN
Field of the Invention
This invention relates to amplifying circuits of electronic equipment.
The invention is applicable to, but not limited to, amplifying circuits of mobile radio units and methods for determining and programing power control levels therein.
Background of the Invention
An amplifier is an electronic circuit which accepts an electrical input and provides an electrical output such that there is a prescribed relationship between the input and output signals. The amplifier circuit requires at least one amplifying device to perform the signal amplification operation. For the majority of amplification circuits used in radio communication applications, the amplifying circuit requires specific power control levels to be applied to the amplifying circuit to ensure that the power gain of the amplifying circuit complies with the desired or specified transmitted power limits imposed on the mobile radio.
One problem associated with the design of amplifier circuits is that each amplifying device varies from other amplifying devices with regard to the power gain of each device for a particular bias voltages current, and also to the frequency response of each amplifying device. This is especially the case with different production batches, even when the amplifying devices are to be used for the same application. A power control function is generally provided to control the output power of a radio to ensure the radio complies with specified limits. The power control line typically dictates how the amplifying device is biased and therefore controls the resultant power gain of the amplifying circuit. Hence, for some applications, there is a need to characterise the power control levels to obtain a specific power gain performance for each amplifier circuit at all possible operating frequencies and over all specified output power ranges.
Typically, the characterisation process is performed in the factory whilst setting up and tuning the radio. However, to measure the power control level required for each power level and each operational frequency is both time consuming and requires a significant amount of memory to store the measured data.
Thus, it is desirable to have an improved method and arrangement to determine power control levels of an amplifier circuit over a large range of frequencies and power levels.
Summarv of the Invention
In a first aspect of the present invention, a method for determining a power control function of a transmitter is provided, in accordance with a preferred embodiment of the invention. The transmitter includes a power amplifier circuit having an input for receiving a low power level input signal and an output operably coupled to an output power sense circuit, for providing an amplified representation of the low power level input signal to the power sense circuit. The output power sense circuit is operably coupled to a microprocessor power control system, which controls a power gain of the power amplifier circuit via at least one power control input. The method includes the steps of inputting a first power control voltage signal by the microprocessor power control system to the power amplifier circuit, measuring a first output power level of the power amplifier circuit by the output power sense circuit and transmitting the first output power level to the microprocessor power control system. A second power control voltage signal is input by the microprocessor power control system to the power amplifier circuit and a second output power level of the power amplifier circuit is measured by the output power sense circuit and transmitted to the microprocessor power control system. A power control function of the relationship between the microprocessor power control system and the power amplifier circuit is then calculated from the two power control voltage signals and measured output powers.
Preferably the transmitter includes a memory element operably coupled to the microprocessor power control system and the method also includes storing the calculated power control function in the memory element by the microprocessor power control system.
In this manner, a power control function for the amplifier circuit can be determined. Advantageously, this power control function is subsequently used to set any output power level of the amplifier circuit that is desired, removing the need to determine each power control level for each frequency of operation and desired output power.
In a preferred embodiment of the first aspect of the present invention, the method also includes inputting a series of frequency signals into the amplifier circuit to determine a frequency response of the amplifying circuit and in particular, the output power sense circuit, e.g. a directional coupler, and storing the frequency response in the memory element for determining power control values over a range of frequencies of the amplifier circuit.
In this manner, a frequency response of the amplifying circuit, and in particular the directional coupler, is determined. The combination of the frequency response of the amplifier circuit and the power control function allows any operating frequency and any operating output power to be calculated and hence an accurate power control level to be programmed into the radio.
In a second aspect of the present invention, a method for progrnmming power control levels of a transmitter circuit is provided, in accordance with a preferred embodiment of the invention. The transmitter circuit includes a power amplifier circuit having an input for receiving both a low power level input signal and a power control input from a microprocessor power control system. The microprocessor power control system includes a memory element and is operably coupled to an input element and to the power amplifier circuit via at least one power control input. The method includes the steps of receiving at least one input from the input element indicative of at least one operating characteristic of the transmitter and deriving a previously stored power control function from the memory element by the microprocessor power control system. A power control voltage signal level is calculated in response to the at least one operating characteristic and the power control function. The calculated power control voltage signal level is then applied to the power amplifier circuit.
In a preferred embodiment of the second aspect of the present invention the amplifier circuit includes an output operably coupled to an output power sense circuit for providing an amplified representation of the low power level input signal to the power sense circuit. The output power sense circuit is operably coupled to the microprocessor power control system and the method also includes the steps of calculating an expected output power level of the amplifier circuit dependent upon the at least one operating characteristic, the calculated power control voltage signal level and the low power level input signal. An output power level of the amplifier circuit is compared to the expected output power level by the microprocessor power control system to determine an error value and the power control voltage signal level is tuned by the microprocessor power control system in order to minimise the error value.
In this manner, the microprocessor power control system programs power control levels of the amplifier circuit dependent upon pre-determined characteristics of the amplifier circuit and any user input made via the input element.
In a third aspect of the present invention a transmitter circuit is provided in accordance with a preferred embodiment of the invention. The transmitter circuit includes a power amplifier circuit having an input for receiving a low power level input signal, a power control input provided from a microprocessor power control system and an output. An output power sense circuit is operably coupled to the output of the power amplifier circuit for providing an amplified representation of the low power level input signal to the power sense circuit, the output power sense circuit is operably coupled to the microprocessor power control system. A microprocessor power control system is included having a memory element, wherein the microprocessor power control system is operably coupled to an input element and to the amplifier circuit via at least one power control input.
In this manner, a radio user inputs desired operating characteristics of the radio. The microprocessor power control system uses this information together with previously determined frequency response data and/or power control voltage versus output power information of the amplifier circuit to accurately determine power control levels to apply to the amplifier circuit.
A preferred embodiment of the invention will now be described, by way of example only, with reference to the drawings.
Brief Description of the Drawings
FIG. 1 is a block diagram of an amplifying circuit according to a preferred embodiment of the invention.
FIG. 2 is a graph showing the relationship between power control signals output from a digital-tbanalog converter and the output power of the amplifier circuit, according to a preferred embodiment of the invention.
FIG. 3 is a flowchart describing a method for determining a power control function in accordance with the preferred embodiment of the invention.
FIG. 4 is a flowchart describing a method for programming a power control function of a transmitter circuit, in accordance with the preferred embodiment of the invention.
Detailed Description of the Drawing Referring first to FIG. 1, a block diagram of a transmitter circuit is shown, according to a preferred embodiment of the invention. The transmitter circuit includes a power amplifier circuit 12 having an input 10 for receiving a low power level input signal, at least one power control input 32 from a microprocessor power control system 36 and an output 26. An output power sense circuit 22, e.g. a directional coupler 24, is operably coupled, via a power sense line 28, to the output of the power amplifier circuit for providing an amplified representation of the low power level input signal to the output power sense circuit 22. The output power sense circuit is operably coupled to the microprocessor power control system 36. The microprocessor power control system 36 has a memory element 38 and is operably coupled to an input element 35, e.g. a user interface element, and to the power amplifier circuit 12 via at least one power control input 32. The power amplifier circuit 12 comprises a series of amplifying stages 14, 16, 18 and 20 although in practice more or less stages may be used. To facilitate the conversion of digital/ analog signals between the output power sense circuit 22 and the microprocessor power control system 36, a digital-to-analog converter (DAC)/ analog-to-digital converter (ADC) block 34, and a power regulator element 30 is provided.
The radio frequency output signal from such transmitters is typically limited, and stringently specified, by regulatory specifications. In addition, the transmitter is required to operate over a large operating power range and over a wide range of frequencies. The transmitter circuit described in FIG. 1 enables accurate power control of the amplifier circuit over a wide range of frequencies by determining a power control function of the amplifier circuit.
Due to component tolerances associated with such transmitter circuits, similar functions will need to be determined for other transmitter circuits.
In operation, the relationship between the microprocessor of the power control voltages and the resultant output power is determined during a factory set-up of the radio. For a particular low level radio frequency input signal, the microprocessor inputs two power control voltages (DAC 1 and
DAC 2) to the amplifier circuit via the digital to analog converter. Output power measurements are made for the respective power control voltages to determine the power control function, namely the relationship between power control signals output from a digital-to-analog converter and the output power of the amplifier circuit 12. The output power measurements are made by feeding back at least a portion of the amplified representation of the low power level input signal from the output of the power amplifier circuit 12 to the output power sense circuit 22. This signal is then converted into a digital form by the DAC/ ADC block 34 and input to the microprocessor power control system 36. The power control function is then stored in a memory element 38. In the preferred embodiment of the invention, the frequency response of the transmitter circuit is also determined to assist in the accurate programming of power control voltage levels across a wide range of frequencies. When the radio is subsequently to be programmed for a particular operating frequency and/or operating power, the stored information is extracted from the memory element 38 and used to determine the required power control voltage signal levels to be applied to the amplifier circuit from the microprocessor power control system 36. Should the performance of the amplifier circuit 12 vary over time, due to say, temperature effects, the output power sense circuit 22 feeds the output power signal to the microprocessor power control system 36 to allow the power control voltage signal to be fine-tuned according to current operating conditions.
Advantageously, power control functions and/or frequency response data is used to determine subsequent operating conditions for the radio unit, without the need for extensive factory testing and programming of all or a substantial amount of operating conditions.
If the RFpower regulator (power control) loop is settled, the RF output power (Pout) can be expressed as a function of the DAC value:
Pout = f (DAC value) (1)
More specifically, it can be shown that all regulated power amplifier systems (shown in FIG. 1) follow the equation:
Pout = (M* DAC value + K)2 (2) where: Pout is the power amplifier output power with a settled loop.
M,K are parameters that describe the realationship between the DAC value controlled by the microprocessor power control system 36 and the amplifier output power. The M and K values are dependent upon the radio design and vary with the tolerances of the circuit components.
Therefore M and K vary from product to product and from unit to unit, but are constant for any particular unit.
To determine the values of M and K two RF output power measurements (P1, P2) are made using predefined default DAC values (DAC1, DAC2). The
M and K values are then calculated using equations (3) and (4) as shown:
To set the desired output power Pout of the radio, the radio software calculates the required DAC setting using the equation:
DACValue = K M Referring now to FIG. 2, a graph showing the relationship between power control signals output from a digital-to-analog converter and the output power of the amplifier circuit, according to a preferred embodiment of the invention, is provided. The graph shows the predominantly square law relationship 40 between the output power level of the amplifier circuit, as sensed by the output power sense circuit 22, and the power control voltage signals provided by the DAC. In order to characterise the relationship 40 a first (DAC 1) and second (DAC 2) power control voltage signals are applied from the microprocessor power control system 36 to the power amplifier circuit 12 via the DAC/ ADC block 34. Respective output power levels are sensed and measured to provide P1 and P2 output power levels, thereby defining the power control function of the transmitter circuit.
Referring now to FIG. 3, a flowchart describing a method for determining a power control function of a transmitter, in accordance with the preferred embodiment of the invention, is shown. The transmitter comprises a power amplifier circuit 12 having an input 10 for receiving a low power level input signal and an output 26 operably coupled to an output power sense circuit 22 for providing an amplified representation of the low power level input signal to the power sense circuit. The output power sense circuit 22 is operably coupled to a microprocessor power control system 36 which controls a power gain of the power amplifier circuit via at least one power control input 32.
The method of FIG. 3 includes the steps of inputting a first power control voltage signal by the microprocessor power control system to the power amplifier circuit, as shown in step 102. A first output power level of the power amplifier circuit is measured by the output power sense circuit, as in step 104, and transmitted to the microprocessor power control system. A second power control voltage signal is input by the microprocessor power control system to the power amplifier circuit, as shown in step 106. A second output power level of the power amplifier circuit is measured, as in step 108, by the output power sense circuit. The second output power level is transmitted to the microprocessor power control system where a power control function of the relationship between the microprocessor power control system and the power amplifier circuit is calculated as shown in step 110.
In the preferred embodiment of the invention, the transmitter further comprises a memory element operably coupled to the microprocessor power control system. The power control function of the relationship includes determination of the M & K values as defined in equation ( ). These values, for the particular radio, transmitter and amplifier circuit under test, are then stored in a memory element of the radio, as shown in step 112. If a frequency response of the output power sense circuit is not determined, the method in FIG. 3 may be used for a number of different operating frequencies. In this manner, the particular power control voltage signal levels for a desired output power level are determined. If the desired frequency is not one that has been previously determined, and a frequency response of the amplifier circuit has not been made, the power control voltage signal level for that frequency is interpolated between two previously calculated and close frequencies.
In this manner, an accurate method for characterising accurate power control levels of an amplifier circuit are made. The calculated function is subsequently used for programming accurate power control levels when a particular user input is received by the microprocessor power control system.
Referring now to FIG. 4, a flowchart describing a method for programming a power control function of a transmitter circuit is shown, in accordance with the preferred embodiment of the invention. The transmitter circuit includes a power amplifier circuit 12 having an input 10 for receiving a low power level input signal and at least one power control input 32 from a microprocessor power control system 36. The microprocessor power control system 36 includes a memory element 38 and is operably coupled to an input element 35 and to the power amplifier circuit 12 via the at least one power control input 32.
The method in FIG. 4 includes the steps of receiving at least one input from the input element 35 indicative of at least one operating characteristic of the transmitter. The power control function is derived from the memory element by the microprocessor power control system, as shown in step 142.
A power control voltage signal level is calculated in response to the at least one operating characteristic and the power control function, as in step 146.
The calculated power control voltage signal level is applied to the power amplifier circuit and used when the amplifier circuit is keyed up, as shown in step 148.
In a preferred embodiment of the invention, the power amplifier circuit 12 includes an output operably coupled to an output power sense circuit 22 which is operably coupled to the microprocessor power control system. The method also includes the steps of calculating an expected output power level of the amplifier circuit dependent upon the at least one operating characteristic, the calculated power control voltage signal level and the low power level input signal. The expected output power level is compared to the measured output power level of the amplifier circuit by the microprocessor power control system to determine an error value. The power control voltage signal level is then tuned by the microprocessor power control system to minimise the error value, thereby facilitating a continued accurate power output level controlled by the microprocessor power control system.
It is also within the contemplation of the invention that the at least one operating characteristic can be input to the input element remotely over the air from a central controller.
With the automatic power control operation described herein there is no need for radio dealers to have test equipment such as power meters and dummy loads to program a radio accurately for a particular operating frequency and output power level. The output power levels and/or operating frequencies can be selected via a user interface. Memory space for the power control levels is significantly reduced when compared to current arrangements and the radio frequency power is accurately programmed over the whole frequency and output power ranges.
Thus, an improved method and arrangement to determine power control levels of an amplifier circuit over a large range of frequencies and power levels is provided. In addition a method of programming the improved power control levels is given with a method for maintaining this optimised performance.
Claims (13)
1. A method for determining a power control function of a transmitter, the transmitter comprising a power amplifier circuit having an input for receiving a low power level input signal and an output operably coupled to an output power sense circuit for providing an amplified representation of the low power level input signal to the output power sense circuit, the output power sense circuit is operably coupled to a microprocessor power control system which controls a power gain of the power amplifier circuit via at least one power control input, the method comprising the steps of:
inputting a first power control voltage signal by the microprocessor power control system to the power amplifier circuit;
measuring a first output power level of the power amplifier circuit by the output power sense circuit and transmitting the first output power level to the microprocessor power control system;
inputting a second power control voltage signal by the microprocessor power control system to the power amplifier circuit
measuring a second output power level of the power amplifier circuit by the output power sense circuit and transmitting the second output power level to the microprocessor power control system; and
calculating a power control function of a relationship between the microprocessor power control system and the power amplifier circuit.
2. The method for determining a power control function of a transmitter according to claim 1, wherein the transmitter further comprises a memory element operably coupled to the microprocessor power control system, the method further comprising the step of storing the calculated power control function in the memory element by the microprocessor power control system.
3. The method for determining a power control function of a transmitter according to any of the preceding claims, wherein the output power sense circuit includes a directional coupler to feed back at least a portion of the amplified representation of the low power level input signal from the output of the power amplifier circuit to the output power sense circuit.
4. The method for determining a power control function of a transmitter according to claim 3, the method further comprising the steps of:
inputting a series of frequency signals into the amplifier circuit to determine a frequency response of the directional coupler; and
storing the frequency response in the memory element for determining power control values over a range of frequencies and a range of power levels of the amplifier circuit.
5. The method for determining a power control function of a transmitter according to any of the preceding claims, wherein the microprocessor power control system includes a digital to analog converter and an analog to digital converter to interface between the microprocessor power control system and the amplifier circuit and enable the microprocessor power control system to control a power gain of the power amplifier circuit via the at least one power control input.
6. The method for determining a power control function of a transmitter according to any of the preceding claims, wherein the method for determination is performed for a particular operating frequency of the transmitter and the steps of inputting, measuring and calculating are repeated for additional operating frequencies of the transmitter.
7. The method for determining a power control function of a transmitter according to any of the preceding claims, wherein the method for determining occurs in a factory set-up process of the transmitter.
8. A method for programming power control levels of a transmitter circuit, the transmitter circuit comprising a power amplifier circuit having an input for receiving a low power level input signal and at least one power control input from a microprocessor power control system wherein the microprocessor power control system includes a memory element and is operably coupled to an input element and to the power amplifier circuit via the at least one power control input, the method comprising the steps of:
receiving at least one input from the input element indicative of at least one operating characteristic of the transmitter circuit;
deriving a power control function by the microprocessor power control system from the memory element;
calculating a power control voltage signal level in response to the at least one operating characteristic and the power control function; and
applying the calculated power control voltage signal level to the power amplifier circuit.
9. The method for programming power control levels of a transmitter circuit according to claim 8, wherein the power amplifier circuit includes an output operably coupled to an output power sense circuit for providing an amplified representation of the low power level input signal to the output power sense circuit, the output power sense circuit is operably coupled to the microprocessor power control system, the method further comprising the steps of:
calculating an expected output power level of the power amplifier circuit dependent upon the at least one operating characteristic, the calculated power control voltage signal level and the low power level input signal;
comparing an output power level of the power amplifier circuit with the expected output power level by the microprocessor power control system to determine an error value; and
tuning the power control voltage signal level by the microprocessor power control system to minimise the error value.
10. The method for programming power control levels of a transmitter circuit according to claims 8 or 9, wherein the input element is a user interface element and the at least one operating characteristic includes at least one of the following: an operating frequency of the transmitter circuit and an output power level of the transmitter circuit.
11. The method for programming power control levels of a transmitter circuit according to claims 8, 9 or 10 wherein the at least one operating characteristic input to the input element is performed remotely over the air from a central controller.
12. The method of any of the preceding claims, wherein the transmitter circuit is a transmitter circuit of a mobile radio unit.
13. A transmitter circuit comprising:
a power amplifier circuit having an input for receiving a low power level input signal, at least one power control input from a microprocessor power control system and an output;
an output power sense circuit operably coupled to the output of the power amplifier circuit for providing an amplified representation of the low power level input signal to the output power sense circuit, the output power sense circuit is operably coupled to the microprocessor power control system; and
a microprocessor power control system having a memory element wherein the microprocessor power control system is operably coupled to an input element and to the power amplifier circuit via at least one power control input.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9603185A GB2310330B (en) | 1996-02-15 | 1996-02-15 | Amplifying circuit and method for determining and programming power control levels therein |
| FR9700871A FR2745130B1 (en) | 1996-02-15 | 1997-01-28 | AMPLIFICATION CIRCUIT AND METHOD FOR DETERMINING AND PROGRAMMING THE LEVELS OF POWER CONTROL IN THIS CIRCUIT |
| HK98101329A HK1002300A1 (en) | 1996-02-15 | 1998-02-20 | Amplifying circuit and method for determining and programming power control levels therein |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9603185A GB2310330B (en) | 1996-02-15 | 1996-02-15 | Amplifying circuit and method for determining and programming power control levels therein |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9603185D0 GB9603185D0 (en) | 1996-04-17 |
| GB2310330A true GB2310330A (en) | 1997-08-20 |
| GB2310330B GB2310330B (en) | 2000-11-29 |
Family
ID=10788802
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9603185A Expired - Fee Related GB2310330B (en) | 1996-02-15 | 1996-02-15 | Amplifying circuit and method for determining and programming power control levels therein |
Country Status (3)
| Country | Link |
|---|---|
| FR (1) | FR2745130B1 (en) |
| GB (1) | GB2310330B (en) |
| HK (1) | HK1002300A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002082643A1 (en) * | 2001-04-05 | 2002-10-17 | Siemens Aktiengesellschaft | Method for power equalisation in hf power amplifiers |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0369135A2 (en) * | 1988-11-17 | 1990-05-23 | Motorola, Inc. | Power amplifier for a radio frequency signal |
| EP0412392A2 (en) * | 1989-08-11 | 1991-02-13 | Motorola Ltd | Amplifier for radio transmitter having controllable output power |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2665988B1 (en) * | 1990-08-14 | 1996-11-22 | Cit Alcatel | METHOD AND DEVICE FOR AUTOMATIC GAIN CONTROL OF A VARIABLE GAIN AMPLIFIER AND THEIR APPLICATION TO THE GAIN CONTROL OF A TUNER, PARTICULARLY FOR A VIDEO COMMUNICATION NETWORK. |
| TW225619B (en) * | 1991-07-19 | 1994-06-21 | Nippon Electric Co | |
| JPH08125469A (en) * | 1994-10-21 | 1996-05-17 | Nec Corp | Output controller for power amplifier |
-
1996
- 1996-02-15 GB GB9603185A patent/GB2310330B/en not_active Expired - Fee Related
-
1997
- 1997-01-28 FR FR9700871A patent/FR2745130B1/en not_active Expired - Fee Related
-
1998
- 1998-02-20 HK HK98101329A patent/HK1002300A1/en not_active IP Right Cessation
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0369135A2 (en) * | 1988-11-17 | 1990-05-23 | Motorola, Inc. | Power amplifier for a radio frequency signal |
| EP0614269A1 (en) * | 1988-11-17 | 1994-09-07 | Motorola, Inc. | Power amplifier for a radio frequency signal |
| EP0632584A1 (en) * | 1988-11-17 | 1995-01-04 | Motorola Inc. | Power amplifier for a radio frequency signal |
| EP0412392A2 (en) * | 1989-08-11 | 1991-02-13 | Motorola Ltd | Amplifier for radio transmitter having controllable output power |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002082643A1 (en) * | 2001-04-05 | 2002-10-17 | Siemens Aktiengesellschaft | Method for power equalisation in hf power amplifiers |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2745130B1 (en) | 1999-03-26 |
| FR2745130A1 (en) | 1997-08-22 |
| GB2310330B (en) | 2000-11-29 |
| GB9603185D0 (en) | 1996-04-17 |
| HK1002300A1 (en) | 1998-08-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20060215 |