GB2420923A - Broadband power amplifier and impedance matching circuit - Google Patents
Broadband power amplifier and impedance matching circuit Download PDFInfo
- Publication number
- GB2420923A GB2420923A GB0425146A GB0425146A GB2420923A GB 2420923 A GB2420923 A GB 2420923A GB 0425146 A GB0425146 A GB 0425146A GB 0425146 A GB0425146 A GB 0425146A GB 2420923 A GB2420923 A GB 2420923A
- Authority
- GB
- United Kingdom
- Prior art keywords
- amplifier circuit
- circuit according
- amplifier
- capacitor
- impedance matching
- 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
Links
- 239000003990 capacitor Substances 0.000 claims abstract description 33
- 238000000034 method Methods 0.000 claims description 6
- 230000001939 inductive effect Effects 0.000 claims description 4
- 230000005669 field effect Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 4
- 230000003071 parasitic effect Effects 0.000 description 2
- 241000531897 Loma Species 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000005476 soldering Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/38—Impedance-matching networks
-
- 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
- H03F1/56—Modifications of input or output impedances, not otherwise provided for
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/28—Impedance matching networks
- H03H11/30—Automatic matching of source impedance to load impedance
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/01—Frequency selective two-port networks
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J5/00—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner
- H03J5/24—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection
- H03J5/242—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection used exclusively for band selection
- H03J5/244—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with a number of separate pretuned tuning circuits or separate tuning elements selectively brought into circuit, e.g. for waveband selection or for television channel selection used exclusively for band selection using electronic means
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/02—Transmitters
- H04B1/04—Circuits
- H04B1/0458—Arrangements for matching and coupling between power amplifier and antenna or between amplifying stages
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/111—Indexing scheme relating to amplifiers the amplifier being a dual or triple band amplifier, e.g. 900 and 1800 MHz, e.g. switched or not switched, simultaneously or not
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03F—AMPLIFIERS
- H03F2200/00—Indexing scheme relating to amplifiers
- H03F2200/36—Indexing scheme relating to amplifiers the amplifier comprising means for increasing the bandwidth
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J2200/00—Indexing scheme relating to tuning resonant circuits and selecting resonant circuits
- H03J2200/10—Tuning of a resonator by means of digitally controlled capacitor bank
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J2200/00—Indexing scheme relating to tuning resonant circuits and selecting resonant circuits
- H03J2200/15—Tuning of resonator by means of digitally controlled inductor bank
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Amplifiers (AREA)
Abstract
An amplifier circuit 100 for use in a radio transmitter includes an RF power amplifier 101 and impedance matching means 117 and 119 for matching the input and output impedances of the power amplifier in a number of frequency bands. The amplifier 100 has an operational bandwidth greater than a decade, e.g. from 30MHz to 512MHz. The impedance matching means 117 and 119 each comprise a single LC section comprising switchable shunt capacitors (e.g. 181 - 189) and switchable series inductors (e.g. 161 - 169). The switches may be PIN diodes or FETs. A design algorithm for selecting the band start and end frequencies is disclosed; Q is maintained constant across all bands. The algorithm allows selection of component values so that a multi-octave frequency range may be covered by the single-section configuration.
Description
TITLE: A4PLIFIER CIRCUITS
FIELD OF THE INVENTION
The present invention relates to amplifier circuits, particularly broadband amplifier circuits including a power amplifier for use in radio coinmunicat ion equipment.
BACKGROUND OF THE INVENTION
Broadband power amplifiers having an operational :.. bandwidth of greater than a decade, e.g. from 30 MHz to 512 MHz at SW output RF power, are becoming widely used 15 in various specialist application radio communications equipment. Such equipment includes radio transmitters used in military applications such as ground and ground to air communications and in public safety applications.
It is necessary in such applications to provide a match of the input and output impedances of the final RF power devices of the RF transmitter including the RF power amplifier. In conventional transmitter circuits the matching is implemented using circuits including an arrangement of transformers, but this can provide only an approximate match. Thus, such circuits are not well suited to use in the specialist broadband applications mentioned above for various reasons, as follows. Such transformers are difficult to produce and can require special operator hand assembly, and are therefore costly to produce and their product quality is soi etimes reduced. Such transformers occupy a relatively large area on a printed circuit board, pcb, e.g. on which the transmitter of a portable radio is assembled, and a relatively large volume (height) on the pcb.
Furthermore, assembly of the transformer circuits on a pcb is complicated and expensive because hand soldering and special construction operations are required.
Furthermore some gluing of the transformer to the pcb may be required.
The purpose of the present invention is to provide an improved amplifier circuit for use in the above applications.
S S S*
SUMMARY OF THE INVENTION I... * . ml..
According to the present invention in a first I..'..
* aspect there is provided an amplifier circuit according * S to claim 1 of the accompanying claims.
*:*:. According to the present invention in a second aspect there is provided a method according to claim 22 * 20 of the accompanying claims.
According to the present invention in a third aspect there is provided a RF transmitter according to claim 23 of the accompanying claims.
Further features embodying the invention are as defined in the accompanying dependent claims.
The invention helps to solve the problems described earlier. The principle of the invention is to use in an amplifier circuit a multiplicity of controllable (selectable) single pole inductive coil-capacitor combinations. As will be familiar to those skilled in the networks art, a single pole' combination of a capacitor C and inductor L means a combination of a parallel connected capacitor C with a series connected inductor L. Each coil and each capacitor in each combination has its own electrically controllable RF switch such as a PIN diode or a FET switch.
One or more of the single pole LC combinations can thereby be selected to select the input and output impedances required in the bands.
An important method of operation in an amplifier circuit embodying the first aspect of the invention uses an algorithm that allows selection of the single-pole component values so that an entire multi-octave frequency range may be covered using the single-pole configuration. As explained in more detail later, the s..
algorithm is based on an approach to give a constant Q e.
across the range to be covered.
The main advantage of the invention is that it is possible to design a multi-octave amplifier in which all inductive and capacitive passive components can be
. 20 assembled automatically on a circuit board such as a pcb, which allows assembly to be done more efficiently and more cheaply. Furthermore, less space and height on a pcb are required by the passive components than in..DTD: comparable prior art circuits and the impedance
selection and matching can be achieved more accurately
than in the prior art.
Another important benefit of the proposed solution provided by the invention is greatly improved amplifier stability owing to the fact that only one LC combination is operational at any one time, i.e. for each band, thus avoiding parasitic resonances which usually are present in a wide band RF amplifier circuit design and lead to unwanted parasitic oscillations.
In this specification an electrically controllable
RF switch' means a switch, present in a circuit to deliver an RF signal, which can be employed to provide operational inclusion or exclusion of an associated passive component (an inductor or a capacitor) in the RF circuit depending on the state of the switch. The state of the switch is selectable depending on the control signal (e.g. 1' or 0' from a logic circuit of a digital signal processor) applied to the switch.
Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which: U...
SSS. 15 e..
BRIEF DESCRIPTION OF THE DRAWINGS
U..... * .
FIG. 1 is a schematic circuit diagram of a power * amplifying circuit embodying the invention.
FIG. 2 is a schematic circuit diagram in more detail of an input circuit of the power amplifying circuit shown in FIG. 1.
FIG. 3 is a schematic circuit diagram in more detail of an input circuit of the power amplifying circuit shown in FIG. 1.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION
FIG. 1 is a schematic circuit diagram of a power amplifying circuit 100 embodying the invention. As shown in FIG 1, a power amplifier comprises a MOSFET power transistor 101. The transistor 101 includes a gate electrode 103, a drain electrode 105 and a source electrode 107. A supply voltage is applied to the drain electrode 105 via a coil 109 one end of which is earthed via a capacitor 111. The source electrode 107 is also earthed. A bias voltage is applied to the gate electrode 103 via a resistor 113 one end of which is connected to earth via a capacitor 115. An input RF signal S1, is applied to the gate electrode 103 serving as an input signal terminal of the transistor 101 via an input circuit 117. An output amplified RF signal S0, is extracted from an output circuit 119 connected to the drain 105 which serves as an output signal terminal of the transistor 101.
The input circuit 117 is shown in more detail in * S..
FIG. 2. The input circuit 117 includes five single helical coil inductors 121, 123, 125, 127 and 129 connected together in series and to the gate electrode * 103. Electrically operable switches 131, 133, 135, 137 and 139 are series connected together in a row and each is connected in series with a corresponding associated one of the inductors 121 - 129. The input circuit 117 also includes five capacitors 141, 143, 145, 147 and 149 connected together in parallel and to the gate electrode 103. Electrically operable switches 151, 153, 155, 157 and 159 are present each connected to an associated one of the capacitors 141 - 149. Each of the switches 151, 153, 155, 157 and 159 is also connected to earth.
The output circuit 119 is shown in more detail in FIG. 3. The output circuit 119 includes five single helical coil inductors 161, 163, 165, 167 and 169 connected together in series and to the drain electrode 105. Electrically operable switches 171, 173, 175, 177 and 179 are series connected together in a row and each is connected in parallel with a corresponding associated one of the inductors 161 - 169. The input circuit 119 also includes five capacitors 181, 183, 185, 187 and 189 connected together in parallel and to the gate electrode 103. Electrically operable switches 191, 193, 195, 197 and 199 are present each connected to an associated one of the capacitors 181 - 189. Each of the switches 191, 193, 195, 197 and 199 is also connected to earth.
In operation, the input impedance of the transistor 101 is matched to that of the output impedance in different operational frequency bands by selecting the SSS *.s..* 15 impedance of the input circuit 117 and of the output S...
circuit 119 by selecting at the appropriate frequency of the band which of the electrically controllable switches is closed so that its associated inductor or capacitor * is switched in or out of the input circuit 117 or output circuit 119 as appropriate. An example is as follows.
S.....
* In order to cover the operational frequency range 30MHz to 512MHz the following conditions were employed: Frequency Range: 30MHz - 512MHz Supply Voltage: 7.5V Power Output: 3W nominal RF transistor 101: PolyFet L8711P (trade name) Pin Diodes (switches 171-179) : MA4P275 (Rs=0.5 ohm max at lOmA).
The following design procedure was used for selection of the components to be operationally present (i.e. switched in) in the output circuit 119. A similar procedure can be used for selection of the components to be operationally present in the input circuit 117: 1. The overall operational frequency range was divided into bands.
2. Each band was selected so that the impedance step up/down had a bandwidth according to Q arising from the impedance step up/down. Q is here defined as the ratio of the band centre frequency to the bandwidth.
Maintaining Q constant across all bands ensures that the band edge mismatch is controlled. The Q of the n-th band is where RnL=50 (where RnL is load impedance) and RnS is S...
: the real part of the load line Z of the transistor 101 in the n-th band.
The n bands may be found using the following algorithm S.....
* (which is a novel general approach per se): S.....
* (i) Start of the algorithm: Set BIL-30MHz (ii) For n = 2,3,4 (until Brjj =512MHZ) compute Qn.
(iii) Compute K from the formula (KI) (iv) Compute the start of the n-th band using B,.L=B(fl1)H (v) Compute the end of the n-th band using B =BK End of the algorithm Using this algorithm applied to the range 30MHz 512MHz we obtained nine bands as listed in the following Table 1.
TABLE 1
Frequency Inductors selected to Capacitors selected Band (MHz) be operation in output to be operational in circuit 119 output circuit 119 30-41 161, 163, 165, 167, 169 181, 183, 185, 187, 189 41-56 161, 163, 165, 169 181, 183, 185, 187 56-77 161,169 181, 189 77-105 161,165,167 185,187 105-144 161,167 183,187 144-198 161,165 181,185,189 198-271 161,165 181,185 271-372 161,163 185 s 372-512 161,163 181, 183 S.....
* : 5 In this example, the inductances of the coils had the following values: 161:2.7nH; 163:5.4nH; 165:10.8nH; 167:21.6nH; 169:43.2nH.
* The capacitors had the following values: * 181:6.7pF; 183:13.4pF; 185:26.8pF; 187:53.6pF; 189:107.2pF.
The inductances of the coils and the capacitances of the capacitors were selected to be related to Qn and the centre frequency of the relevant band so their values were preclefined and could be stored in a
predefined table.
A simulation was carried out using a simulation software tool ADS' (trade name), including relevant models for the transistor, the PIN diodes and the passive components.
The results obtained are shown in Table 2 as follows:
TABLE 2
Band Number Band (MHz) Worst case Worst case row VSWR 1 30 - 41 0.33 1.99 2 41 - 56 0.26 1.70 3 56 - 77 0.34 2.03 4 77 - 105 0.4 2.33 s.. ______________________- 105 - 144 0.49 2.92 6 144 - 198 0.4 2.33 7 198 271 0.51 3.08 Ie**s 8 271 - 372 0.49 2.92
_______________________ _______________________
* 9 372 - 512 0.48 2.85 * 0 0 * S. The results in Table 2 show that the circuits of FIG.s 2 and 3 provide expected results and demonstrates suitability in a wideband amplifier circuit.
Claims (23)
1. An amplifier circuit for use in a radio transmitter, including a RF power amplifier and impedance matching means for matching the input and output impedances of the power amplifier in a plurality of frequency bands, the impedance matching means including, connected to a signal terminal of the power amplifier, a plurality of inductive coil-capacitor individually selectable single pole combinations, each of the capacitors and coils having an associated electrically controllable switch to control switching of . 15 the capacitor or inductor in or out of the circuit.
2. An amplifier circuit according to claim 1 wherein S.....
* . the impedance matching means includes, connected to each of an input signal terminal and an output signal terminal of the amplifier, a plurality of capacitors and a plurality of non-transformer inductors, each of the capacitors and inductors having an associated electrically controllable switch to control switching of the capacitor or inductor in or out of the circuit.
3. An amplifier circuit according to claim 1 or claim 2 wherein the capacitors are connected directly together in a parallel bank arrangement.
4. An amplifier circuit according to any one preceding claims wherein the circuit includes a plurality of arms connected in electrical parallel each including one of the capacitors and the switch associated with the capacitor connected to the capacitor.
5. An amplifier circuit according to claim 4 wherein each of the arms is connected to ground and the switch associated with each capacitor is connected between the capacitor and ground.
6. An amplifier circuit according to any one of the preceding claims wherein the inductors are connected directly together in electrical series.
7. An amplifier according to any one of the preceding claims wherein the switch associated with each inductor is connected in electrical parallel with its associated inductor.
8. An amplifier circuit according to any one of the preceding claims wherein the inductors are single coil *:::: 15 inductors.
9. An amplifier circuit according to any one of the * * preceding claims including a controller for controlling the application of control signals to the switches to * * control selectively the state of the switches.
10. An amplifier according to claim 9 wherein the controller is operable to apply control signals such that in the impedance matching means connected to a signal terminal or each of a plurality of signal terminals of the power amplifier only a selected one of the capacitors and a selected one of the inductors is switched in the amplifier circuit.
11. An amplifier circuit according to claim 10 wherein the controller is operable to apply control signals such that in the impedance matching means connected to a signal terminal or to each of a plurality of signal terminals of the power amplifier, different capacitor- inductor combinations are selected in different frequency bands by selection of appropriate switches.
12. An amplifier circuit according to claim 11 which is operable in n different frequency bands using n different capacitor-inductor combinations, where n is an integer selected to give substantially constant Q across all bands, Q being the ratio between the centre frequency and bandwidth of each frequency band.
13. An amplifier circuit according to claim 11 or claim 12 wherein the circuit is operable to provide selection of at least six different capacitor-inductor combinations each in a different frequency band.
14. An amplifier circuit according to claim 13 wherein the circuit is operable to provide selection of at least *..se, 15 nine different capacitor-inductor combinations each in a S...
different frequency band.
15. An amplifier circuit according to any one of the preceding claims wherein the power amplifier is operable * in a frequency range which includes the range 30 MHz to 512 MHz.
:":
16. An amplifier circuit according to any one of the preceding claims wherein the power amplifier comprises a power transistor.
17. An amplifier circuit according to any one of the preceding claims wherein the power transistor comprises
a field effect transistor.
18. An amplifier circuit according to any one of the preceding claims wherein at least one of the switches comprises a PIN diode switch.
19. An amplifier circuit according to any one of the preceding claims wherein at least one of the switches comprises a transistor switch.
20. An amplifier circuit according to any one of the preceding claims wherein the switches are included together in an integrated circuit.
21. An amplifier circuit according to claim 1 and substantially as herein described with reference to the accompanying drawings.
22. A method of operating an amplifier circuit for use in a radio transmitter, including a RF power amplifier and impedance matching means for matching the input and output impedances of the power amplifier in a plurality of frequency bands, the impedance matching means * 15 including, connected to a signal terminal of the power amplifier, a plurality of inductive coil-capacitor individually selectable single pole combinations, each of the capacitors and coils having an associated electrically controllable switch to control switching of . 20 the capacitor or inductor in or out of the circuit, the method including operating the switches to select different coil-capacitor combinations in different operational frequency bands.
23. A RF transmitter including an amplifier circuit according to any one of preceding claims 1 to 21.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0425146A GB2420923B (en) | 2004-11-15 | 2004-11-15 | Amplifier circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0425146A GB2420923B (en) | 2004-11-15 | 2004-11-15 | Amplifier circuit |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB0425146D0 GB0425146D0 (en) | 2004-12-15 |
| GB2420923A true GB2420923A (en) | 2006-06-07 |
| GB2420923B GB2420923B (en) | 2007-05-02 |
Family
ID=33523731
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0425146A Expired - Fee Related GB2420923B (en) | 2004-11-15 | 2004-11-15 | Amplifier circuit |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2420923B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1914886A1 (en) * | 2006-10-19 | 2008-04-23 | Alcatel Lucent | Multi-band power amplifier |
| CN101867347B (en) * | 2009-04-15 | 2012-12-12 | 中国科学院电子学研究所 | Power amplifier circuit with reconfigurable frequency band in multi-band wireless mobile communication system |
| CN110932747A (en) * | 2019-12-02 | 2020-03-27 | 翱捷智能科技(上海)有限公司 | Integrated high-performance radio frequency transmit-receive switch |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3794941A (en) * | 1972-05-08 | 1974-02-26 | Hughes Aircraft Co | Automatic antenna impedance tuner including digital control circuits |
| US4201960A (en) * | 1978-05-24 | 1980-05-06 | Motorola, Inc. | Method for automatically matching a radio frequency transmitter to an antenna |
-
2004
- 2004-11-15 GB GB0425146A patent/GB2420923B/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3794941A (en) * | 1972-05-08 | 1974-02-26 | Hughes Aircraft Co | Automatic antenna impedance tuner including digital control circuits |
| US4201960A (en) * | 1978-05-24 | 1980-05-06 | Motorola, Inc. | Method for automatically matching a radio frequency transmitter to an antenna |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1914886A1 (en) * | 2006-10-19 | 2008-04-23 | Alcatel Lucent | Multi-band power amplifier |
| CN101867347B (en) * | 2009-04-15 | 2012-12-12 | 中国科学院电子学研究所 | Power amplifier circuit with reconfigurable frequency band in multi-band wireless mobile communication system |
| CN110932747A (en) * | 2019-12-02 | 2020-03-27 | 翱捷智能科技(上海)有限公司 | Integrated high-performance radio frequency transmit-receive switch |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0425146D0 (en) | 2004-12-15 |
| GB2420923B (en) | 2007-05-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20111115 |