GB2310341A - Transmitter circuit and antenna switch - Google Patents
Transmitter circuit and antenna switch Download PDFInfo
- Publication number
- GB2310341A GB2310341A GB9603187A GB9603187A GB2310341A GB 2310341 A GB2310341 A GB 2310341A GB 9603187 A GB9603187 A GB 9603187A GB 9603187 A GB9603187 A GB 9603187A GB 2310341 A GB2310341 A GB 2310341A
- Authority
- GB
- United Kingdom
- Prior art keywords
- antenna switch
- amplifier stage
- power
- transmitter circuit
- radio
- 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.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/74—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of diodes
-
- 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
- H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
- H04B1/40—Circuits
- H04B1/44—Transmit/receive switching
- H04B1/48—Transmit/receive switching in circuits for connecting transmitter and receiver to a common transmission path, e.g. by energy of transmitter
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Transmitters (AREA)
Description
TRANSMITTER CIRCUIT AND ANTENNA SWITCH
Field of the Invention
This invention relates to transmitter circuits of communication units. The invention is applicable to, but not limited to, antenna switches and amplifier designs of such transmitter circuits for mobile /portable radios and methods of controlling the operation of such amplifier designs and antenna switches.
Background of the Invention
In modern mobile and portable radio equipment there is an everincreasing need to miniaturise product size, reduce power dissipation and meet stringent performance criteria. In particular, it is desirable to reduce power dissipation, and hence increase the operating efficiency, in such radio equipment by reducing the component count for transmitter operations.
In addition, most of the European countries now have to comply with the European Telecommunication Standard ETS 300-113 for radio emissions. In particular, ETS 300-113 specifies stringent adjacent channel power transient specifications for periods of ramping-up the transmitter's power. Such specifications are typically difficult to comply with due to, amongst other factors, the combination of switching on power supplies of the transmitter circuit, transient effects from switching modulation and frequency-mixing signals into the transmitter path and transient effects due to the rate of increase of radio frequency signal levels.
This invention seeks to provide a transmitter circuit, and method of operation, to mitigate at least some of the problems highlighted above.
Summarv of the Invention
In a first aspect of the preferred embodiment of the present invention, a transmitter circuit is provided. The transmitter circuit includes an antenna switch having an output operably coupled to an antenna for controlling transmission and reception of radio frequency signals to and from the antenna and at least one amplifier stage for receiving a first radio-frequency input signal and for providing to an input of the antenna switch an amplified radio-frequency output signal, wherein the antenna switch is directly responsive to an operation of the at least one amplifier stage.
In this manner, the antenna switch operation is dictated by an operation of the at least one amplifier stage.
Preferably, the transmitter circuit also includes a power source operably coupled to the at least one amplifier stage and to the antenna switch thereby facilitating the direct responsive operation of the antenna switch according to an operation of the at least one amplifier stage. In the preferred embodiment of the invention, a feedback circuit couples the input of the antenna switch to the power source to enable the operation of the antenna switch to respond directly to a power level of the first radiofrequency input signal. A matching circuit is included to match an output of the at least one amplifier stage to the power source to optimise power transfer of the first radio-frequency input signal to the antenna switch.
In this manner, the antenna switch responds to the power source applied to the at least one amplifier stage which in turn is responsive to the input first radio-frequency input signal. Advantageously, no additional power source is required to operate the antenna switch and hence there are no resistive losses due to the power source and no resultant switching transients due to the activation of such a power source. In addition, the operation of the antenna switch for a transmit mode is initiated automatically when the transmitter circuit is ramped up.
In a second aspect of the present invention, a method of operating a transmitter circuit is provided. The transmitter circuit includes an antenna switch with an output operably coupled to an antenna for controlling transmission and reception of radio frequency signals to and from the antenna and operably coupled to at least one amplifier stage. The method includes the step of generating an output of the antenna switch in direct response to an operation of the at least one amplifier stage.
In this manner the antenna switch operation is controlled by an operation of the at least one amplifier stage.
In a preferred embodiment of the second aspect of the present invention, the transmitter circuit further includes a power source operably coupled to the at least one amplifier stage and to the antenna switch. The step of generating an output of the antenna switch in direct response to an operation of the at least one amplifier stage includes the steps of receiving a first radio-frequency input signal at an input of the at least one amplifier stage, increasing a power source input to the at least one amplifier stage in response to a power level of the first radio-frequency input signal and operating the antenna switch in direct response to the power source input to the at least one amplifier stage.
In this manner, the antenna switch responds to the power source applied to the at least one amplifier stage which in turn is responsive to the input first radio-frequency input signal.
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 a prior art transmitter circuit.
FIG. 2 is a block diagram of a transmitter circuit, according to a preferred embodiment of the invention.
FIG. 3 is a graph showing a performance improvement of the transmitter circuit according to a preferred embodiment of the invention.
FIG. 4 is a flow chart of a method of operating the transmitter circuit in accordance with the preferred embodiment of the invention.
Detailed Description of the Drawings
Referring first to FIG. 1, a block diagram of a prior art transmitter circuit is shown. The transmitter circuit of FIG. 1 shows a multi-stage power amplifier chain. An input radio frequency signal (Pin) 10 is fed to a switch 12 controlled by a switch control signal 14. The switch is connected to an input of a first amplifier stage 16 which has a first power source 18 and an output to an input of a second amplifier stage 20 which has in turn a second power source 22. In a similar manner, other stages may be connected as shown. A final amplifier stage 24 has a final power source 26 and an output connected to an input of a PIN diode antenna switch 28. The output of the final amplifier stage 24 and input of the PIN diode antenna switch 28 is connected to a voltage/ current source 36 via a radio-frequency choke 30 and a high-power dissipation resistor 32. The output 42 of the PIN diode antenna switch 28 is connected to an antenna (not shown) and a second radio-frequency choke 38 to a receiver circuit with the second radiofrequency choke 38 being coupled to ground via high power dissipation resistor 40. A power control signal 17 is shown connected to the first amplifier stage to control the radio frequency power gain through the amplifier chain.
In operation, the input radio frequency signal (Pin) 10 inputs a low power radio frequency signal to the power amplifier chain. The switch 12 is typically a PIN diode switch, controlled by a control signal with a timing to meet the ETS Adjacent Channel Transients Specification. The switch may also be located between the amplifier stages. The power control signal 17 is used to regulate the output power (Pout) of the power amplifier chain.
The PIN diode antenna switch 28 is used as transmit/receive antenna switch and is controlled by the voltage/ current source 36. A positive bias across the PIN diode antenna switch 28 creates a low impedance and enables transmit signals to pass from the amplifier stages to the antenna, whilst a negative bias across the PIN diode antenna switch 28 creates a high impedance and isolates the antenna from the transmit path, thereby allowing receive signals to pass from the antenna to the receiver. The radio frequency (RF) chokes (RFCs) 30 and 38 have a high impedance for
RF and low impedance for direct current (DC) signals. The high power dissipation resistors 32 and 40 limit the dc current through the PIN diode antenna switch 28. It is possible for only one of these resistors to be used and for the power sources to each amplifier stage to be supplied from a single power source.
Some of the disadvantages associated with such prior art transmitter designs include: (i) PIN diode current (Ipin) needs to be chosen for maximum possible RF output power. For example, typically Ipin = 100 mA for a 0.1 to 25W power amplifier design. Hence, the dissipated power is significant with Pdiss=I2R + any temperature loss. Such a current level requires a high power dissipation resistor 32 with a typical power dissipation level of 1.5
Watts being measured; (ii) a separate power source is typically used for controlling the operation of the PIN diode antenna switch 28 and the amplifier stages; (iii) in order to meet the ETS 300-113 Adjacent Channel Transients
Specification a switch 12 is typically necessary to improve isolation between input and output of the power amplifier chain and minimise the transient effects of switching on the PIN diode antenna switch 28; and (iv) the operation of switch 12 may cause undesirable instability problems within the transmitter circuit.
Referring now to FIG. 2, a block diagram of a transmitter circuit is shown, according to a preferred embodiment of the invention. The transmitter circuit includes a PIN diode antenna switch 72 having an output 76 operably coupled to an antenna for controlling transmission and reception of radio frequency signals to and from the antenna and at least one amplifier stage for receiving a first radio-frequency input signal 50 and for providing to an input of the PIN diode antenna switch 72 an amplified radio-frequency output signal 63, wherein the PIN diode antenna switch 72 is directly responsive to an operation of the at least one amplifier stage.
Preferably, the transmitter circuit includes a power source operably coupled to the at least one amplifier stage and to the antenna switch thereby facilitating a direct responsive operation of the antenna switch according to an operation of the at least one amplifier stage. This direct response facilitation is provided by a feedback circuit from the input of the antenna switch to the power source to enable the operation of the antenna switch to respond directly to a power level of the first radio-frequency input signal. The feedback circuit includes a matching circuit to match an output of the at least one amplifier stage to the power source to optimise power transfer of the first radio-frequency input signal to the antenna switch. In the preferred embodiment of the invention the antenna switch is a pin diode antenna switch having a pin diode input bias supplied from the power source and the power source varies with a power level of the first radio-frequency input signal thereby increasing a dynamic range of output power of the at least one amplifier stage and limiting power dissipation from the antenna switch.
In the preferred embodiment of the invention, the transmitter circuit of FIG. 2 shows a multi-stage power amplifier chain. However, the invention is equally applicable to a single power amplifier stage. An input radio frequency signal (Pin) 50 is fed to a first amplifier stage 52 which has a power control source 54 and an output to an input of a second amplifier stage 58 which has in turn a power source 60. In a similar manner, other stages may be connected as shown. A final amplifier stage 24 has a final power source 26 and an output connected to an input of a PIN diode antenna switch 28. The output of the final amplifier stage 62 and input of the PIN diode antenna switch 72 is connected via a feedback circuit 66 to the first amplifier stage 52 and the second amplifier stage 58 via a radiofrequency choke 68 and a DC blocking capacitor 70 providing low impedance for RF and high impedance for DC. The radio-frequency choke 68 and a DC blocking capacitor 70 are also designed to match the output of the final amplifier stage 62 to the antenna switch to optimise the power transferred from the final amplifier stage 62 to the antenna. The output 76 of the PIN diode antenna switch 72 is connected to an antenna (not shown) and via a second radio-frequency choke 74 to a receiver circuit.
In operation, the input radio frequency signal (Pin) 50 inputs a low power radio frequency signal to the power amplifier chain. This input causes the first amplifier stage to draw current from the power control source 54. As the current is drawn from the power control source 54 the first amplifier stage 52 amplifies the input radio frequency signal (Pin) 50 and inputs the amplified signal to the second amplifier stage 58 which draws current from its power source 60. This current is fed to the PIN diode antenna switch 72 to bias the PIN diode antenna switch 72 for transmitter operations. Biasing the PIN diode antenna switch 28 positively creates a low impedance and enables transmit signals to pass from the amplifier stages to the antenna. It is within the contemplation of the invention that the DC current of one or more amplifier stages are fed to the
PIN diode antenna switch 72 via the feedback circuit 66.
In an alternative embodiment of the invention, the biasing of the PIN diode antenna switch 72 is controlled by the power control source 54.
Advantageously, in the preferred embodiment of the invention, no resistor is required at the input of the PIN diode switch and thus there is no resistive power dissipation loss. No initial additional switch is necessary to improve isolation as the amplifiers are activated when a radio frequency input signal is received and the PIN diode antenna switch 72 is negatively biased to provide additional isolation. There is a reduction in power dissipation of driver stage(s) due to voltage drop (typically approx.
1VDC) across the PIN diode antenna switch 72. The PIN diode current is adapted to the desired output power and not, as in the prior art transmitter circuit, permanently arranged to provide for the maximum available output power. This enables the transmitter circuit to be effectively used across a wider power range. A separate power source for the PIN diode antenna switch 72 is not required as the bias input is provided by at least one of the amplifier stages thereby reducing the problems associated with transient interference in switching on transmitter power sources. This is accomplished as the Ibias of the final stage is used as a collector current for at least one earlier amplifier stage thereby facilitating the DC power consumption being increased as the input radio frequency signal (Pin) 50 is increased.
Referring now to FIG. 3, a graph highlighting a performance improvement of the transmitter circuit is shown, according to a preferred embodiment of the invention. The graph shows output power versus time for various amplifier circuits. Graph 80 shows the performance of the prior art transmitter circuit of FIG. 1 without the switch 12. It is noticeable that any signal input to the amplifier chain is at a relatively high level and hence, not effectively isolated from the antenna. This type of performance would fail spurious emission limits during receiver operation of the mobile radio unit. Graph 82 shows the performance of the prior art transmitter circuit of FIG. 1 with the switch 12 included. Any signal input to the amplifier chain is at a low level, but the effect of switching on power supplies to facilitate transmitter operation, e.g. switching on the PIN diode antenna switch 28, causes significant transient problems with the generation of undesirable "spikes". This type of performance would cause problems in meeting adjacent channel power transient specifications limits during the transmitter ramp-up function. Graph 84 shows the performance of the transmitter circuit of FIG. 2 in accordance with the preferred embodiment of the invention. Any signal input to the amplifier chain is at a low level as the PIN diode antenna switch 72 isolates the amplifier chain and any input signal from the antenna and the amplifier power sources are disabled due to the removal of an input signal.
Transient problems due to undesirable "spikes" are removed as the transient effect generators of a separate PIN diode control power source and additional antenna switch are removed.
Referring now to FIG. 4, a method of operating a transmitter circuit in accordance with a preferred embodiment of the invention is provided.
The transmitter circuit includes a PIN diode antenna switch 72 with an output operably coupled to an antenna for controlling transmission and reception of radio frequency signals, to and from the antenna, and operably coupled to at least one amplifier stage. The method includes the step of generating an output of the antenna switch in direct response to an operation of the at least one amplifier stage.
In the preferred embodiment the transmitter circuit also includes a power source operably coupled to the at least one amplifier stage and to the antenna switch. The method as described in FIG. 4 includes the steps of receiving a first radio-frequency input signal at an input of the at least one amplifier stage, as shown in step 102, increasing a power source input to the at least one amplifier stage in response to a power level of the first radio-frequency input signal, as in step 104, and operating the antenna switch in direct response to the power source input to the at least one amplifier stage, as shown in step 106. In an alternative embodiment of the invention the method includes the step of providing a power control signal to the at least one amplifier stage to control a power gain of the at least one amplifier stage and thereby the operation of the antenna switch.
It is within contemplation of the invention that the multiamplifier stages can be replaced by a single amplifier stage and that at least one amplifier power source is used to control the operation of the antenna switch. In the preferred embodiment of the invention, the antenna switch is a PIN diode antenna switch.
Thus a transmitter circuit and method of operation are provided that mitigate some of the problems associated with undesired transmitter power dissipation and meeting stringent adjacent channel power transient specifications.
Claims (13)
1. A transmitter circuit comprising:
an antenna switch having an output operably coupled to an antenna for controlling transmission and reception of radio frequency signals to and from the antenna; and
at least one amplifier stage for receiving a first radio-frequency input signal and for providing to an input of the antenna switch an amplified radio-frequency output signal, wherein the antenna switch is directly responsive to an operation of the at least one amplifier stage.
2. The transmitter circuit of claim 1, further comprising:
a power source operably coupled to the at least one amplifier stage and to the antenna switch thereby facilitating a direct responsive operation of the antenna switch according to an operation of the at least one amplifier stage.
3. The transmitter circuit of any of the preceding claims, further comprising:
a feedback circuit from the input of the antenna switch to the power source to enable the operation of the antenna switch to respond directly to a power level of the first radio-frequency input signal.
4. The transmitter circuit of claim 3, wherein the feedback circuit comprises a matching circuit to match an output of the at least one amplifier stage to the power source to optimise power transfer of the first radio-frequency input signal to the antenna switch.
5. The transmitter circuit of any of the preceding claims, wherein the antenna switch is a pin diode antenna switch having a pin diode input bias supplied from the power source.
6. The transmitter circuit of any of the preceding claims, wherein power supplied by the power source varies with a power level of the first radio-frequency input signal thereby increasing a dynamic range of output power of the at least one amplifier stage and limiting power dissipation from the antenna switch.
7. The transmitter circuit of any of the preceding claims, further comprising a power control signal input to at least one of the plurality of amplifier stages, wherein the power control signal determines the level of amplification of the at least one of the plurality of amplifier stages.
8. The transmitter circuit of claim 7, wherein the power control signal is the at least one power source from the input of the antenna switch.
9. The transmitter circuit of any of the preceding claims, wherein the at least one amplifier stage is a plurality of radio-frequency power amplifier stages for use in a mobile radio.
10. A method of operating a transmitter circuit having an antenna switch with an output operably coupled to an antenna for controlling transmission and reception of radio frequency signals to and from the antenna and operably coupled to at least one amplifier stage, the method comprising the step of:
generating an output of the antenna switch in direct response to an operation of the at least one amplifier stage.
11. The method of operating a transmitter circuit according to claim 10, wherein the transmitter circuit further includes a power source operably coupled to the at least one amplifier stage and to the antenna switch, wherein the step of generating an output of the antenna switch in direct response to an operation of the at least one amplifier stage includes the steps of:
receiving a first radio-frequency input signal at an input of the at least one amplifier stage;
increasing a power source input to the at least one amplifier stage in response to a power level of the first radio-frequency input signal; and
operating the antenna switch in direct response to the power source input to the at least one amplifier stage.
12. The method of operating a transmitter circuit according to claim 10, wherein the method further comprises the step of:
providing a power control signal to the at least one amplifier stage to control a power gain of the at least one amplifier stage and thereby the operation of the antenna switch.
13. A transmitter circuit substantially as described herein with respect to FIG. 2 of the drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9603187A GB2310341A (en) | 1996-02-15 | 1996-02-15 | Transmitter circuit and antenna switch |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9603187A GB2310341A (en) | 1996-02-15 | 1996-02-15 | Transmitter circuit and antenna switch |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9603187D0 GB9603187D0 (en) | 1996-04-17 |
| GB2310341A true GB2310341A (en) | 1997-08-20 |
Family
ID=10788804
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9603187A Withdrawn GB2310341A (en) | 1996-02-15 | 1996-02-15 | Transmitter circuit and antenna switch |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2310341A (en) |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4380822A (en) * | 1981-11-02 | 1983-04-19 | Motorola, Inc. | Transmit-receive switching circuit for radio frequency circulators |
| EP0151014A2 (en) * | 1984-01-27 | 1985-08-07 | Nec Corporation | Radio transceiver including an antenna switching circuit |
| GB2273423A (en) * | 1992-12-10 | 1994-06-15 | Motorola Gmbh | An electrical switching circuit for a radio receiver |
-
1996
- 1996-02-15 GB GB9603187A patent/GB2310341A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4380822A (en) * | 1981-11-02 | 1983-04-19 | Motorola, Inc. | Transmit-receive switching circuit for radio frequency circulators |
| EP0151014A2 (en) * | 1984-01-27 | 1985-08-07 | Nec Corporation | Radio transceiver including an antenna switching circuit |
| GB2273423A (en) * | 1992-12-10 | 1994-06-15 | Motorola Gmbh | An electrical switching circuit for a radio receiver |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9603187D0 (en) | 1996-04-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5541554A (en) | Multi-mode power amplifier | |
| US6085074A (en) | Apparatus and method for amplifying an amplitude-varying signal | |
| US6169449B1 (en) | Transmission power control circuit capable of varying electric power over a wide range | |
| KR100293484B1 (en) | Transmitter for mobile communication that can selectively activate amplifiers | |
| JP3904817B2 (en) | Power amplifier module | |
| EP0397444B1 (en) | Circuitry for widening the effective range of a transmitter | |
| US5559471A (en) | Amplifier and biasing circuit therefor | |
| EP1800395B1 (en) | Dual bias control circuit | |
| EP1897216B1 (en) | Automatic bias control circuit for linear power amplifiers | |
| US6445247B1 (en) | Self-controlled high efficiency power amplifier | |
| US6356150B1 (en) | Portable integrated switching power amplifier | |
| EP0397445A2 (en) | Procedure for forming low power levels in a radio telephone transmitter | |
| EP1387486B1 (en) | Amplifier circuit and multistage amplifier circuit | |
| JPH07154169A (en) | High frequency power amplifier | |
| US6201441B1 (en) | Semiconductor circuit | |
| US6624700B2 (en) | Radio frequency power amplifier for cellular telephones | |
| WO2005022740A2 (en) | Method and apparatus providing integrated load matching using adaptive power amplifier compensation | |
| WO2004013957A2 (en) | Circuit for power amplification | |
| JP2006217362A (en) | Limiter circuit | |
| JP3228740B2 (en) | Power amplifier | |
| US6838932B2 (en) | Power amplifier capable of adjusting operating point | |
| US6122491A (en) | Communications system using power amplifier with dynamic biasing | |
| US20060114062A1 (en) | Self adaptable bias circuit for enabling dynamic control of quiescent current in a linear power amplifier | |
| US6725026B2 (en) | Intermodulation control device and method in mobile communication system | |
| US6253070B1 (en) | Diode amplifier bypass circuit |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |