GB2418792A - An efficient mobile phone transmitter amplifier with an adapted power supply voltage - Google Patents

An efficient mobile phone transmitter amplifier with an adapted power supply voltage Download PDF

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Publication number
GB2418792A
GB2418792A GB0421745A GB0421745A GB2418792A GB 2418792 A GB2418792 A GB 2418792A GB 0421745 A GB0421745 A GB 0421745A GB 0421745 A GB0421745 A GB 0421745A GB 2418792 A GB2418792 A GB 2418792A
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GB
United Kingdom
Prior art keywords
power
transmission
voltage
converter
output
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
Application number
GB0421745A
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GB0421745D0 (en
GB2418792B (en
Inventor
Surinder Singh Thind
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Samsung Electronics Co Ltd
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Samsung Electronics Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Samsung Electronics Co Ltd filed Critical Samsung Electronics Co Ltd
Priority to GB0421745A priority Critical patent/GB2418792B/en
Publication of GB0421745D0 publication Critical patent/GB0421745D0/en
Publication of GB2418792A publication Critical patent/GB2418792A/en
Application granted granted Critical
Publication of GB2418792B publication Critical patent/GB2418792B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/0205—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
    • H03F1/0211—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers with control of the supply voltage or current
    • H03F1/0216—Continuous control
    • H03F1/0222—Continuous control by using a signal derived from the input signal
    • H03F1/0227—Continuous control by using a signal derived from the input signal using supply converters
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/0205—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/02—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/0205—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
    • H03F1/0211—Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers with control of the supply voltage or current
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/24—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers of transmitter output stages
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03G—CONTROL OF AMPLIFICATION
    • H03G3/00—Gain control in amplifiers or frequency changers without distortion of the input signal
    • H03G3/004—Control by varying the supply voltage
    • 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

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Transmitters (AREA)

Abstract

The power supply voltage for an RF power amplifier 12 in a mobile phone is varied in dependence on the baseband gain control signal. This raises the amplifier efficiency when the amplifier input signal level is low. The baseband gain control signal is modified by a non-linear shaping circuit 18 (figure 5) which supplies a reference signal to the DC-DC converter 14 supplied by a battery 16. A look-up table is not needed for producing the reference signal, which can now be generated promptly and easily for each transmission slot.

Description

241 8792 Transmitter Efficienc,,r Control The present invention relates to
a power output control, and particularly to a power output control for a mobile phone.
One known form of mobile telecommunications relates to a cellular system. In this system radio wave frequencies are used as carrier channels, with the data to be transmitted superimposed thereon. The process of combining the data to be transmitted and the radio wave is known as modulation. Sets of radio wave frequency carrier channels are used within discrete areas (known as cells). Only a finite amount of radio frequencies are available, and hence sets of frequencies are required to be re-used in order to meet demand. Fig. 1 shows a simplified example of a cellular system. Each hexagon represents a cell. Numeral fi represents a first set of frequencies, f2 represents a second set of frequencies and so on. It will be noticed that there are two frequency sets marked fi (the two cells being labelled fi(a) and fi(b)).
Therefore, the transmission power in frequency fi(a) needs to be controlled so as not to interfere with the frequency set in set fi(b). For this reason, and others, it is highly desirable to control the power output of a mobile terminal.
It is also desirable to control the power output of a mobile terminal so as to preserve the battery power of the mobile terminal. It is highly desirable to reduce the power supplied from the battery pack as the level of transmission from the mobile phone is reduced. Generally, in order to achieve the above aims, the voltage supply to the power amplifier of the mobile terminal needs to be reduced as the voltage level of the transmission signal is reduced.
Fig. 2 shows a known arrangement adapted to control the output of a power amplifier, and hence the power output of a mobile terminal.
Fig. 2 shows a transmission integrated circuit, a power amplifier and a DC/DC converter. The battery of the mobile terminal is connected directly to the DC/DC converter.
The DC/DC converter uses an input reference signal (being a variable voltage) to control the level of power supplied from the battery to the power 1 0 amplifier.
A second signal (supplied as a variable voltage) is input to the transmission circuit. This signal is a base band gain control, and is used to the control transmission power of the mobile handset.
In this system, in order the ensure an appropriate output of the power amplifier, the two input signals need to be synchronised. This is generally performed by using electronic look-up tables (LUT) stored in the central processor. The LUT is generated from test data from mobile terminals, and is configured such that certain performance ranges of the mobile terminal do not violate 3GPP conformance requirements. The performance ranges may include temperature, adjacent channel leakage ratio and relative power step changes over extreme voltage.
A particular problem with this arrangement is that the voltage level of the reference signal cannot be changed quickly, due to the processing time required, thus UE transmitter output power and PA supply from DC/DC converter could be out of synchronization and this could lead to 3GPP non conformance.
Cellular communication systems generally define a plurality of time slots of when a mobile terminal can send or receive information, each timeslot being of the order of 667 microseconds. The processing time for comparing the reference signal with values in the LUT and outputting reference signal is greater than this.
Thus the input signal to the DC/DC converter (and hence the voltage input thereto) cannot be quickly changed. Therefore the voltage supplied to the power amplifier cannot be changed with every transmission time slot as is becoming necessary with more modern systems. Accordingly, it is not possible to optimise the efficiency of the transmission power of a mobile handset.
The present invention seeks to overcome this problem.
According to the present invention there is provided a power output control comprising: a transmission means, a power amplifier operable to receive an output from the transmission means, a power source operable to supply a voltage to the power amplifier, wherein, a transmission signal input to the transmission means is used to control the power supplied from the power source to the power amplifier.
Preferably the power output control further comprises a DC/DC converter operable to modify the voltage output from the power source, and supply the modified voltage to the power amplifier.
Preferably the transmission signal is input directly to both the DC/DC 5converter and the transmission means.
In a most preferred embodiment the transmission signal is passed through a shaping circuit before being input to DC/DC converter.
In a preferred embodiment the shaping comprises temperature compensation means.
10In a preferred embodiment the power output control is used within a mobile phone.
According to a second aspect of the present invention there is provided a power control for a mobile phone using a base band gain control signal to control the output voltage of a power source.
15It is preferred that the base band controls the output of a DC/DC converter.
In order that the present invention be more readily understood, specific embodiments thereof will now be described with reference to the 20accompanying drawings.
Fig. 1 shows a simplified cell structure in a mobile telecommunications network.
Fig. 2 shows an example of a known power output control.
Fig. 3 shows a graph illustrating optimum DC/DC converter input against transmission power.
Fig. 4 shows an embodiment of a power output control according to the invention.
Fig. 5 shows an example of a shaping circuit in the embodiment of figure 4.
Fig. 6 shows a graph illustrating DC/DC converter input against transmission power using the arrangement of figs 4 and 5.
It is desirable to reduce the supply to the power amplifier as transmission power output is reduced in order to optimise transmission efficiency. The present embodiment describes a hardware approach to controlling the power output of a mobile handset, and accordingly allows for greater optimisation of transmission efficiency.
The prior art approach uses two signals. The first is a base band gain control signal (Vga) that is input to the transmission circuit 10. The transmission circuit 10 inputs the transmission signal (Vga) through the power amplifier 12.
A DC/DC converter 14 controls the power supplied from a battery 16 to the power amplifier 12 in accordance with a second signal. A DC/DC converter is a device that accepts a DC input voltage and produces a DC output voltage typically the output produced is at a different voltage level than the input.
The output from the DC/DC converter 14 is controlled by a reference signal (PA ref). This reference signal is used in conjunction with a look- up
table.
In order for the arrangement to function properly the base band gain control signal (Vga) and reference signal (PA ret) need to be synchronized.
Fig. 3 is a graph showing the change of transmission power with a change of the DC/DC converter 14 input voltage (i.e. the magnitude of the reference signal). This graph represents the optimum transmission power output in terms of efficiency and performance of a mobile handset.
However, the prior art has the drawback that the processing time (i.e. comparing reference signal values with values in the look-up-table) may take a relatively long time, and hence the transmission voltage input to the power amplifier cannot be changed with every transmission time slot.
The present invention allows for more rapid change in transmission power, and hence allows for a greater optimization of the transmission output.
Fig. 4 shows an embodiment of the present invention. This embodiment removes the need for a second reference signal and the accompanying look up-tables, by relying instead on hardware to simulate the necessary transmission output.
The present arrangement includes a commercially available transmission circuit (transmit chip) 10 and a UMTS (universal mobile telecommunications system) radio frequency power amplifier 12. A transmission signal is input to the transmission circuit 10 and modulated with the data to be transmitted. The modulated signal is input to the power amplifier 12 and then transmitted. This arrangement is as the prior art. The present embodiment further comprises a shaping circuit 18, a battery pack 16 and a DC/DC converter 14.
The present embodiment uses only one signal - the base band gain control signal (Vga). This signal is input through the transmission circuit 10, as in the prior art arrangement. However, the same signal is also input to a shaping circuit 18. The output from the shaping circuit 18 is input to the DC/DC converter 14. It is this signal that controls the voltage supplied from the battery 16 to the power amplifier 12. Thus, the transmission signal (i.e. voltage level) controls the power supplied from the power source 16.
Therefore when the transmission signal changes, the level of power supplied will be automatically controlled. In other words, as the voltage level of the base band gain control rises or falls, the power supplied from the battery 16 to the power amplifier 12 will automatically rise or fall accordingly. Therefore, there is no processing time delay.
However, the transmission signal has a linear response with respect to transmission power, i.e. as the voltage level of the transmission signal increases, so does the transmission power. This is illustrated in figure 6.
Figures 3 & 6 show the optimum relationship between DCIDC converter 14 input voltage and transmission power. Therefore some means of shaping the transmission signal input to the DC/DC converter is required to ensure that a suitable output is obtained.
Figure 5 shows an example of a shaping circuit 18. Resistors R1, R2, R3 and diode D2 are used to set initial operating conditions to give a constant output (VDCDC) when diode D1 is not conducting. This will be the case during low transmission power, as the voltage level of the base band gain control (Vga) will also be low. Resistor R2 can be selected to change operating (conducting) point of diode D1. As the base band (Vga) voltage increases with increasing transmission power, diode D1 will start conducting when base band voltage increases above that across R1 and D2. The forward current in a standard silicon diode is given by I = Is {exp(eV/KT)- 13 Is - Leakage current (reverse current) e - electron charge K - Boltzman's constant T - temperature (Kelvins) V - Forward voltage across diode.
As the transmission signal increases - or in other words, as the voltage of the transmission input rises - the current flowing through diode D1 will increase exponentially according to the above equation The combined voltage across R1 and D2 will also rise, causing the input to the DC/DC converter to match the optimum requirement of DC/DC converter input to the transmission output.
In order to function in a mobile phone, the performance of the shaping circuit must be consistent over a temperature range of -10 to +55 C. Diodes D1 and D2 provide temperature compensation. As forward voltage of D2 drifts with temperature, so does the voltage across D1, balancing the drift across D2. If the diodes are matched then variation with temperature will be mmmzed.
Figure 6 shows a graph of input voltage to a DC/DC converter against mobile terminal power output for the following specific values: R1 = lkQ, R2 = 2kQ, R3 = 330Q and D1 and D2 = IN4148 standard silicon diodes. Three lines are shown. These are a plot of the input voltage - i.e. the magnitude of the base band gain control signal - both unshaped, and shaped according to the invention. The third line shows the optimum plot for these variables.
As will be noted, the shaped output is close to the optimum characteristics for transmission power output and voltage input.
The above embodiments are described by way of example only, and many modifications and variations are possible within the scope of the present invention.

Claims (9)

  1. CLAIMS: 1. A power output control comprising: a transmission means; a
    power amplifier operable to receive an output from the transmission means; a power source operable to supply a voltage to the power amplifier, wherein a transmission signal input to the transmission means is used to control the power supplied from the power source to the power amplifier.
  2. 2. A power output control according to claim 1 further comprising a DC/DC converter operable to modify the voltage output from the power source, and supply the modified voltage to the power amplifier.
  3. 3. A power output control according to either claim 1 or claim 2 wherein the transmission signal is input directly to both the DC/DC converter and the transmission means.
  4. 4. A power output control according to claim 3 wherein the transmission signal is passed through a shaping circuit before being input to DC/DC converter.
  5. 5. A power output control according to claim 4 wherein the shaping circuit comprises temperature compensation means.
  6. 6. A power output control according to claim 4 or claim 5, wherein said shaping circuit comprises a diode/resistor network.
  7. 7. A power control for a mobile phone using a base band gain control signal to control the output voltage of a power source.
  8. 8. A power control according to claim 7 wherein said base band gain control signal controls the output of a DC/DC converter.
  9. 9. A mobile phone comprising a power output control according to any preceding claim.
GB0421745A 2004-09-30 2004-09-30 Transmitter efficiency control Expired - Fee Related GB2418792B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB0421745A GB2418792B (en) 2004-09-30 2004-09-30 Transmitter efficiency control

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB0421745A GB2418792B (en) 2004-09-30 2004-09-30 Transmitter efficiency control

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GB0421745D0 GB0421745D0 (en) 2004-11-03
GB2418792A true GB2418792A (en) 2006-04-05
GB2418792B GB2418792B (en) 2008-10-22

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007128862A1 (en) 2006-05-05 2007-11-15 Nokia Corporation Method and arrangement for optimizing efficiency of a power amplifier
US7622984B2 (en) 2006-12-22 2009-11-24 Wolfson Microelectronics Plc Charge pump circuit and methods of operation thereof
US7626445B2 (en) 2006-12-22 2009-12-01 Wolfson Microelectronics Plc Charge pump circuit and methods of operation thereof
US7714660B2 (en) 2006-06-30 2010-05-11 Wolfson Microelectronics Plc Amplifier circuit and methods of operation thereof
US7990742B2 (en) 2006-12-22 2011-08-02 Wolfson Microelectronics Plc Charge pump circuit and methods of operation thereof
US8363856B2 (en) 2006-12-22 2013-01-29 Wolfson Microelectronics ple Audio amplifier circuit and electronic apparatus including the same

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GB2323987A (en) * 1994-01-29 1998-10-07 Motorola Ltd A radio transceiver amplifier with closed loop gain control feedback for a trunked mode and open loop bias feedback for a direct mode
WO2003075452A2 (en) * 2002-03-01 2003-09-12 Sige Semiconductor Inc. Method of adjusting gain and current consumption of a power amplifier circuit while maintaining linearity
US6636112B1 (en) * 1999-07-29 2003-10-21 Tropian, Inc. High-efficiency modulating RF amplifier
US6694130B2 (en) * 1998-12-29 2004-02-17 Skyworks Solutions, Inc. System and method for dynamically varying operational parameters of an amplifier

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US5420536A (en) * 1993-03-16 1995-05-30 Victoria University Of Technology Linearized power amplifier
FI20020990A (en) * 2002-05-27 2003-11-28 Nokia Corp A method for controlling signal power in a transmitter in a radio system and a transmitter in a radio system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2323987A (en) * 1994-01-29 1998-10-07 Motorola Ltd A radio transceiver amplifier with closed loop gain control feedback for a trunked mode and open loop bias feedback for a direct mode
US6694130B2 (en) * 1998-12-29 2004-02-17 Skyworks Solutions, Inc. System and method for dynamically varying operational parameters of an amplifier
US6636112B1 (en) * 1999-07-29 2003-10-21 Tropian, Inc. High-efficiency modulating RF amplifier
WO2003075452A2 (en) * 2002-03-01 2003-09-12 Sige Semiconductor Inc. Method of adjusting gain and current consumption of a power amplifier circuit while maintaining linearity

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2016672A4 (en) * 2006-05-05 2010-03-10 Nokia Corp Method and arrangement for optimizing efficiency of a power amplifier
EP2016672A1 (en) * 2006-05-05 2009-01-21 Nokia Corporation Method and arrangement for optimizing efficiency of a power amplifier
WO2007128862A1 (en) 2006-05-05 2007-11-15 Nokia Corporation Method and arrangement for optimizing efficiency of a power amplifier
US8373506B2 (en) 2006-06-30 2013-02-12 Wolfson Microelectronics Plc Amplifier circuit and methods of operation thereof
US8660277B2 (en) 2006-06-30 2014-02-25 Wolfson Microelectronics Plc Amplifier circuit and methods of operation thereof
US7714660B2 (en) 2006-06-30 2010-05-11 Wolfson Microelectronics Plc Amplifier circuit and methods of operation thereof
US11652405B2 (en) 2006-06-30 2023-05-16 Cirrus Logic, Inc. Amplifier circuit and methods of operation thereof
US8183931B2 (en) 2006-06-30 2012-05-22 Wolfson Microelectronics Plc Amplifier circuit and methods of operation thereof
US8279012B2 (en) 2006-06-30 2012-10-02 Wolfson Microelectronics Plc Amplifier circuit and methods of operation thereof
US11031863B2 (en) 2006-06-30 2021-06-08 Cirrus Logic, Inc. Amplifier circuit and methods of operation thereof
US10587187B2 (en) 2006-06-30 2020-03-10 Cirrus Logic, Inc. Amplifier circuit and methods of operation thereof
US9685855B2 (en) 2006-06-30 2017-06-20 Cirrus Logic, Inc. Amplifier circuit and methods of operation thereof
US9673700B2 (en) 2006-06-30 2017-06-06 Cirrus Logic, Inc. Amplifier circuit and methods of operation thereof
US9306448B2 (en) 2006-06-30 2016-04-05 Cirrus Logic International Semiconductor Ltd. Amplifier circuit and methods of operation thereof
US9236794B2 (en) 2006-12-22 2016-01-12 Cirrus Logic International Semiconductor Ltd. Charge pump circuit and methods of operations thereof
US7626445B2 (en) 2006-12-22 2009-12-01 Wolfson Microelectronics Plc Charge pump circuit and methods of operation thereof
US8427851B2 (en) 2006-12-22 2013-04-23 Wolfson Microelecttronics plc Charge pump circuit and methods of operation thereof
US9917508B2 (en) 2006-12-22 2018-03-13 Cirrus Logic, Inc. Charge pump circuit and methods of operation thereof
US7622984B2 (en) 2006-12-22 2009-11-24 Wolfson Microelectronics Plc Charge pump circuit and methods of operation thereof
US8363856B2 (en) 2006-12-22 2013-01-29 Wolfson Microelectronics ple Audio amplifier circuit and electronic apparatus including the same
US7990742B2 (en) 2006-12-22 2011-08-02 Wolfson Microelectronics Plc Charge pump circuit and methods of operation thereof

Also Published As

Publication number Publication date
GB0421745D0 (en) 2004-11-03
GB2418792B (en) 2008-10-22

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Effective date: 20140930