KR20090102890A - Class-E power amplifier having improved power efficiency - Google Patents

Class-E power amplifier having improved power efficiency

Info

Publication number
KR20090102890A
KR20090102890A KR1020080028132A KR20080028132A KR20090102890A KR 20090102890 A KR20090102890 A KR 20090102890A KR 1020080028132 A KR1020080028132 A KR 1020080028132A KR 20080028132 A KR20080028132 A KR 20080028132A KR 20090102890 A KR20090102890 A KR 20090102890A
Authority
KR
South Korea
Prior art keywords
transistor
impedance matching
power
load impedance
lc network
Prior art date
Application number
KR1020080028132A
Other languages
Korean (ko)
Inventor
김창우
구광회
Original Assignee
경희대학교 산학협력단
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 경희대학교 산학협력단 filed Critical 경희대학교 산학협력단
Priority to KR1020080028132A priority Critical patent/KR20090102890A/en
Publication of KR20090102890A publication Critical patent/KR20090102890A/en

Links

Classifications

    • HELECTRICITY
    • H03BASIC ELECTRONIC CIRCUITRY
    • H03FAMPLIFIERS
    • H03F1/00Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/02Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
    • H03F1/0205Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers
    • H03F1/0261Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers with control of the polarisation voltage or current, e.g. gliding Class A
    • H03F1/0266Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation in transistor amplifiers with control of the polarisation voltage or current, e.g. gliding Class A by using a signal derived from the input signal
    • HELECTRICITY
    • H03BASIC ELECTRONIC CIRCUITRY
    • H03FAMPLIFIERS
    • H03F1/00Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/56Modifications of input or output impedances, not otherwise provided for
    • H03F1/565Modifications of input or output impedances, not otherwise provided for using inductive elements
    • HELECTRICITY
    • H03BASIC ELECTRONIC CIRCUITRY
    • H03FAMPLIFIERS
    • H03F3/00Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/189High frequency amplifiers, e.g. radio frequency amplifiers
    • H03F3/19High frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only
    • H03F3/193High frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only with field-effect devices
    • HELECTRICITY
    • H03BASIC ELECTRONIC CIRCUITRY
    • H03HIMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/38Impedance-matching networks

Abstract

The present invention relates to the improvement of the efficiency of a power amplifier that can be utilized in a wireless terminal system device, etc., the power amplifier according to the present invention to minimize the effect of parasitic capacitance generated on the transistor output side, to further improve the power efficiency characteristics load impedance Tuning inductors have been added to the matching LC network, preferably with variable inductors, which reduces the parasitic capacitance components of large transistors used to achieve large output power, while increasing flexibility in transistor size selection. And having a larger optimization tuning range, it is advantageous to optimize the load impedance matching LC network for high efficiency.

Description

Class-E power amplifier having improved power efficiency

The present invention can be utilized in the field of using a wireless terminal system device and a high power efficiency power amplifier.

As a long life time of a mobile terminal battery is required, a high efficiency characteristic of a power amplifier, a core circuit that consumes a lot of power, is greatly required. The power amplifier is the most important part of the transmitter stage and has the biggest influence on the overall efficiency. Increasing the efficiency of a power amplifier can reduce the additional cost of using a cooling system in terms of base stations and repeaters, and can also increase the life of the battery in terms of terminals. Therefore, the efficiency of the power amplifier is one of the important factors to consider in the design.

The power amplifier is classified into class-A, B, AB, C, D or E according to the power efficiency of the amplifier defined as the ratio of output power to input power. The class-E amplifier is an amplifier for high efficiency characteristics of output power. Used in devices that require high power efficiency, theoretically, Class-E amplifiers are devices with 100% power consumption efficiency. Compared to the low efficiency of other amplifiers such as Class-A, B, AB, etc., it is theoretically perfect efficiency and designed for high efficiency. However, contrary to theory, Class-E amplifiers have efficiency less than the theoretical value due to the non-ideal physical component and device physical operation characteristics, and such excessive difference causes a big problem in the role of high efficiency amplifier. .

In general, in the case of the conventional power amplifier, a large output voltage swing cannot be obtained due to a limited bias voltage, so that a large amount of current flows through the transistor to obtain a large output power through the large current. Therefore, in order to allow a large amount of current to flow and to handle this, the size of a transistor is considerably larger than that of a general amplifier, and a single small transistor is connected in a large number in parallel to operate as a single large transistor. At this time, the parasitic capacitance of the parallel transistors is increased by the parallel structure, which may result in an adverse effect on the output power and efficiency characteristics by the transistor size. Therefore, there is a need for proper optimization between transistor size and power efficiency characteristics.

Transistors of the conventional Class-E amplifier also use the plurality of single transistor parallel connection structures, and accordingly, it is required to select a transistor size optimized for output power and efficiency.

An object of the present invention is to provide a power amplifier that has been devised to solve the above problems, and which improves power efficiency and enables a wider tuning range.

A power amplifier according to the first aspect of the present invention for achieving the above object is a transistor connected to a single or a plurality of single transistors, the power is connected to the drain terminal of the transistor, a predetermined signal is applied to the gate terminal of the transistor; A load impedance matching LC network connected to the drain terminal of the transistor; At least one tuning inductor connected in series with a capacitor having a capacitance to be adjusted for impedance matching according to a change in parasitic capacitance of the transistor among components of the load impedance matching LC network; And a load resistor connected to the load impedance matching LC network, and controlling a predetermined signal applied to the gate terminal of the transistor by using the output of the power source. Preferably the tuning inductor is a variable inductor.

The transistor is preferably a MOSFET or similar field effect transistor (FET).

A power amplifier according to a second aspect of the present invention for achieving the above object is a transistor connected to a single or a plurality of single transistors, the power is connected to the collector terminal of the transistor, a predetermined signal is applied to the base terminal of the transistor; A load impedance matching LC network coupled to the collector terminal of the transistor; At least one tuning inductor connected in series with a capacitor having a capacitance to be adjusted for impedance matching according to a change in parasitic capacitance of the transistor among components of the load impedance matching LC network; And a load resistor connected to the load impedance matching LC network, and controlling a predetermined signal applied to the base terminal of the transistor by using the output of the power source.

The transistor is preferably a bipolar junction transistor or a transistor of a similar type.

As described above, according to the present invention, the effect of parasitic capacitance increases while increasing the size of the transistor is more effectively canceled by using a tuning inductor, so that the size of the transistor can be more flexibly selected and a larger optimization tuning range can be obtained. This allows the optimization of load impedance matching LC networks for high efficiency. In addition, the power amplifier according to the present invention can achieve higher power efficiency than the conventional structure through a simple circuit structure.

1 is a circuit diagram illustrating a conventional Class-E amplifier.

2 is a circuit diagram of a Class-E amplifier according to an embodiment of the present invention.

3 is an enlarged MOS transistor structure diagram of only a portion of the transistor 201 of FIG. 2.

4 is a graph showing the power efficiency of a Class-E amplifier according to the C1 capacitance value of a load impedance matching LC network for a fixed transistor size.

5 is a graph showing power efficiency of a Class-E amplifier according to an inductance value of a tuning inductor for a fixed transistor size and a fixed load impedance matching LC network capacitor C1 according to an embodiment of the present invention.

FIG. 6A is a graph illustrating power efficiency according to the number of transistor fingers in the circuit diagram of FIG. 1, and FIG. 6B is power efficiency according to the number of gate fingers of a transistor in a state in which a tuning inductor is added according to an exemplary embodiment of the present invention. Is a graph.

<Explanation of symbols for the main parts of the drawings>

101,201: Transistor

102,202: Load impedance matching LC network

103,203: Load resistance

104,204: RF Choke Inductors

205 tuning inductor

301: Drain-Source Capacitance

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following examples are provided to aid the understanding of the present invention and the present invention is not limited to the following examples.

1 is a circuit diagram illustrating a conventional Class-E amplifier.

As shown, a conventional Class-E amplifier includes a transistor 101, a load impedance matching LC network 102, a load resistor 103 and an RF choke inductor 104. Here, VDD is a circuit driving voltage, and by applying an input signal such as a pulse form to the Vin terminal, which is the gate input side of the transistor 101, without a separate DC power supply, the transistor 101 made of a transistor is switched on or off according to the pulse waveform. It will turn off. Thus, the current and voltage characteristics with respect to time in this switch become 180 ° out-of-phase to obtain a large power efficiency.

The load impedance matching LC network 102 is composed of capacitors C1 and C2 and an inductor L1, and achieves an impedance matching between the load resistor 103 and the transistor 101 for maximum output power, and outputs a target frequency. It acts as a filter for. The selection of the capacitors C1 and C2 and the inductor L1, which are the constituent elements, is based on a well-known method, and a detailed description thereof will be omitted. Here, the RF choke inductor 104 blocks the RF signal and serves to flow only the DC current. That is, as shown, the signal applied to the Vin terminal is amplified through the transistor 101 and the signal through which impedance matching and filtering of the target frequency are performed through the load impedance matching LC network 102 is output through Vout. .

2 is a circuit diagram of a Class-E amplifier according to an embodiment of the present invention.

As shown, a transistor 201, a load impedance matching LC network 202, a load resistor 203, an RF choke inductor 204, and a tuning inductor L2 205 are provided, and a load impedance matching LC network 202 is provided. At least one tuning inductor 205 is connected in series to C1, which is a component of. Here, the illustrated transistor 201 represents only one transistor, but is preferably composed of a plurality of single transistors connected in parallel to increase the maximum output power of the output terminal. In addition, although the present embodiment is configured using a MOSFET, other similar FET transistors or BJTs and similar semiconductor devices can be used. When the present embodiment is implemented using a BJT, the gate, source, and drain terminals of the MOSFET are formed. It is preferable to apply to the base, emitter and collector terminals of the BJT.

Here, the configuration and role of the load impedance matching LC network 202 is the same as above, and the capacitor C1 blocks the DC current flowing to the tuning inductor L2.

FIG. 3 is an enlarged MOS transistor structure diagram of only the transistor 201 of FIG. 2. As shown, there is a capacitance component Cgs that exists between the source and the gate of the MOS transistor, a capacitance component Cgd that exists between the gate and the drain, and a capacitance component Cds 301 that exists between the drain and the source. These capacitance components, which are necessarily present in such MOS transistors, are affected as the size of transistor M1 increases. Among the capacitance components, the capacitance component which has the greatest influence on the load impedance matching LC network 202 is Cds 301. As the size of transistor M1 increases, the parasitic capacitance of transistor M1 increases in parallel and increases, so that load The capacitance value of component C1 of the impedance matching LC network 202 should be small for the performance of the constant load impedance matching LC network 202. Therefore, the size of the transistor 201 suitable for the circuit characteristics is limited, which limits the tuning range of the Class-E amplifier efficiency.

2 and 3 together, the tuning inductor L2 205 is connected to the capacitor C1 in series, the impedance relationship, It is possible to have a positive impedance value by, which can be used to offset the influence of the increased Cds at the same time as transistor M1 increases by using positive impedance, instead of limiting the method of reducing the capacitance value of capacitor C1. That is, no matter how small the C1 capacitance value is for impedance matching, it is left as any value, and the inductor is connected to give a negative effect. Accordingly, the tuning inductor 205 preferably uses a variable inductor. As the tuning inductor 205 is used, the tuning inductor 205 can obtain a wide tuning range by optimizing the load impedance matching LC network 202 characteristics and power efficiency of the amplifier using the variable inductor.

4 is a graph showing the power efficiency of a Class-E amplifier according to the C1 capacitance value of the load impedance matching LC network 102 for a fixed transistor 101 size. That is, in the circuit diagram of FIG. 1, the maximum efficiency point is found while fixing the size of the transistor M1 and changing the size of the C1 capacitance.

Here, PAE (power added efficiency) is an efficiency that accurately counts only the power generated by the power amplifier, and is represented by Equation 1 below.

PAE = 100 * {[P OUT ] RF- [P IN ] RF } / [P DC ] TOTAL

As shown, power efficiency can be optimized by varying the C1 capacitance value of the load impedance matching LC network 102 when the size of the transistor 101 is constant. As the C1 capacitance value becomes smaller, the parasitic capacitance of the transistor M1 is reduced. It is the result of reducing the effect on the ingredients, and shows an efficiency of approximately 83% at the highest point.

FIG. 5 is a graph illustrating power efficiency of a Class-E amplifier according to an inductance value of a tuning inductor for a fixed transistor size and a fixed load impedance matching LC network capacitor C1 according to an embodiment of the present invention. That is, in the circuit diagram of FIG. 2, the maximum efficiency point is found while fixing the magnitudes of the transistors M1 and C1 capacitance and changing the inductance value of the tuning inductor L2 205.

Here, the C1 capacitance value of the load impedance matching LC network 202 is fixed to a small value, and the power efficiency may be optimized by changing the inductance value of the tuning inductor 205 while the DC current is blocked. In FIG. 5, the inductor was tuned to show 88% efficiency at its highest point. Accordingly, the results of FIG. 5 show higher power efficiency than FIG. 4 and show that the tuning inductor 205 has a wider power efficiency tuning range.

6A is a graph illustrating power efficiency according to the number of transistor fingers in FIG. 1, and FIG. 6B is a graph illustrating power efficiency according to the number of transistor fingers in a state in which a tuning inductor is added according to an embodiment of the present invention.

In FIG. 6A, the capacitor C1 value is fixed to 0.1 pF in FIG. 1 without the tuning inductor, and only the number of fingers of the transistor M1 is changed. The highest efficiency is about 83%. In contrast, in FIG. 6B, only the number of fingers of the transistor M1 was changed with the capacitor C1 value of 0.1 pF and the tuning inductor 205 value of 10.1 nH as described above. As a result, it was confirmed that the parasitic capacitance effect as the size of the transistor is increased can be attenuated through the tuning inductor according to the present embodiment.

The present invention is not limited to the embodiments described above, and various modifications and changes can be made by those skilled in the art, which are included in the spirit and scope of the present invention as defined in the appended claims.

Claims (6)

  1. A transistor to which a power source is connected to a drain terminal of the transistor and a predetermined signal is applied to a gate terminal of the transistor;
    A load impedance matching LC network connected to the drain terminal of the transistor;
    At least one tuning inductor connected in series with a capacitor having a capacitance to be adjusted for impedance matching according to a change in parasitic capacitance of the transistor among components of the load impedance matching LC network; And
    And a load resistor connected to the load impedance matching LC network, and controlling a predetermined signal applied to a gate terminal of a transistor by using the output of the power supply.
  2. The power amplifier of claim 1, wherein the tuning inductor is a variable inductor.
  3. 3. The power amplifier of claim 1 or 2, wherein the transistor is a MOSFET or similar field effect transistor (FET).
  4. A transistor to which a power source is connected to a collector terminal of the transistor and to which a predetermined signal is applied to the base terminal of the transistor;
    A load impedance matching LC network coupled to the collector terminal of the transistor;
    At least one tuning inductor connected in series with a capacitor having a capacitance to be adjusted for impedance matching according to a change in parasitic capacitance of the transistor among components of the load impedance matching LC network; And
    And a load resistor connected to the load impedance matching LC network, and controlling a predetermined signal applied to a base terminal of a transistor by using the output of the power supply.
  5. 5. The power amplifier of claim 4 wherein the tuning inductor is a variable inductor.
  6.  6. The power amplifier as claimed in claim 4 or 5, wherein the transistor is a bipolar junction transistor or a similar type transistor.
KR1020080028132A 2008-03-27 2008-03-27 Class-E power amplifier having improved power efficiency KR20090102890A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020080028132A KR20090102890A (en) 2008-03-27 2008-03-27 Class-E power amplifier having improved power efficiency

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020080028132A KR20090102890A (en) 2008-03-27 2008-03-27 Class-E power amplifier having improved power efficiency

Publications (1)

Publication Number Publication Date
KR20090102890A true KR20090102890A (en) 2009-10-01

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120188671A1 (en) * 2009-11-09 2012-07-26 Xilinx, Inc. T-coil network design for improved bandwidth and electrostatic discharge immunity
US20120242284A1 (en) * 2011-03-25 2012-09-27 Qualcomm Incorporated Filter for improved driver circuit efficiency and method of operation
WO2013014521A1 (en) * 2011-07-28 2013-01-31 Toyota Jidosha Kabushiki Kaisha Electric power supply apparatus, contactless electricity transmission apparatus, vehicle, and contactless electric power transfer system

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120188671A1 (en) * 2009-11-09 2012-07-26 Xilinx, Inc. T-coil network design for improved bandwidth and electrostatic discharge immunity
US8453092B2 (en) * 2009-11-09 2013-05-28 Xilinx, Inc. T-coil network design for improved bandwidth and electrostatic discharge immunity
US20120242284A1 (en) * 2011-03-25 2012-09-27 Qualcomm Incorporated Filter for improved driver circuit efficiency and method of operation
US10381874B2 (en) * 2011-03-25 2019-08-13 Qualcomm Incorporated Filter for improved driver circuit efficiency and method of operation
WO2013014521A1 (en) * 2011-07-28 2013-01-31 Toyota Jidosha Kabushiki Kaisha Electric power supply apparatus, contactless electricity transmission apparatus, vehicle, and contactless electric power transfer system
JP2013030973A (en) * 2011-07-28 2013-02-07 Nippon Soken Inc Power supply device, contactless power transmission apparatus, vehicle, and contactless power transmission system

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