Patent Application
20120309327
The present invention relates to the field of amplifiers.
Antennas and antenna arrays may be designed to have the ability to operate in both a transmit mode and a receive mode. Transmit/receive (TR) systems associated with such antennas and antenna arrays typically have two electrical paths, one path for when the TR system is in a receive mode, and another path for when the TR system is in a transmit mode. Accordingly, conventional TR chips require a switch network to implement bidirectional operation. The switch network enables TR systems to both allow an electrical signal, such as a transmit signal, produced by the TR system to be transmitted to, and radiated by, the antenna, and also allow information detected by the antenna to be sent via an electrical signal, such as a receive signal, to be analyzed by the TR system.
A TR system may include a 3-port circulator for low-loss/high-power applications, which may be coupled at a first port to an antenna, or antenna array, at a second port to the input of a receive amplifier, and at a third port to the output of a transmit amplifier. In such a TR system, the output of the receive amplifier and the input of the transmit amplifier can be coupled to a single pole, double throw static switch. Accordingly, the amplifiers may be alternately coupled between the antenna and the remainder of the TR system via operation of the switch and the circulator.
Alternatively, the circulator may be replaced by a second single pole, double throw static switch, which allows the antenna to be alternately coupled to the input of the receive amplifier and the output of the transmit amplifier. Accordingly, when the TR system is operating in a transmit mode, the switches operate to electrically couple the antenna to the remainder of the system via the transmit amplifier, while electrically isolating, or decoupling, the receive amplifier from the antenna and the rest of the system, so that the system processor may deliver a transmit signal to the antenna. When the TR system is operating in a receive mode, the switches flip, thereby coupling the antenna to the rest of the TR system via the receive amplifier while electrically isolating the transmit amplifier from the antenna and the rest of the system, so that the system processor may receive a receive signal detected by the antenna.
Loss due to conventional switch networks, directly effects the noise performance of a receive amplifier located in the electrical path used for the receive mode of the TR system. Furthermore, such loss also effects the performance of a transmit amplifier used in the electrical path for the transmit mode, thereby contributing to degradation of the range of the antenna and reducing the capability of the TR system.
Embodiments of the present invention integrate tuning elements, capacitors, and transistors of the input matching network of transmit and receive amplifiers with those of a switch to achieve the functions of, and therefore, obviate the need for, switches and circulators in TR systems by allowing transmit and receive amplifiers to operate as signal switches. By removing the need for switches or circulators, and thereby reducing the number of electronic elements required to achieve bidirectional RF capability in the TR system, loss due to a switch network is reduced, while the cost to fabricate the TR system, as well as the amount of space required by the TR system, are also reduced. Furthermore, embodiments of the present invention provided an amplifier that may be operated as a signal switch.
In accordance with one exemplary embodiment of the present invention, there is provided an antenna system including a system processor, an antenna element, a receive amplifier including an input coupled to the antenna element, and an output coupled to the system processor, and a transmit amplifier including an input coupled to the output of the receive amplifier, and an output coupled to the input of the receive amplifier.
The input of the receive amplifier may be directly coupled to the output of the transmit amplifier, and the output of the receive amplifier may be directly coupled to the input of the transmit amplifier.
The system processor may be configured to receive a receive signal from the antenna element via the receive amplifier, and may be configured to transmit a transmit signal to the antenna element via the transmit amplifier.
The inputs of the receive amplifier and transmit amplifier may each include a switch transistor.
A gate of each switch transistor may be coupled to the system processor, each switch transistor may be configured to operate as a signal switch, and the system processor may be configured to control each switch transistor in accordance with a transmit mode and a receive mode of the antenna system.
The receive amplifier and the transmit amplifier may be configured to alternately allow electrical signals to pass therethrough.
The outputs of the receive amplifier and the transmit amplifier may each include an amplifier transistor.
The system processor may be coupled to gates of the amplifier transistors and may be configured to control a gate bias voltage of the amplifier transistors to control the amplifier transistors in accordance with a transmit mode or a receive mode of the antenna system.
The receive amplifier and the transmit amplifier may each include a plurality of tuning elements coupled to transmission lines.
One or more of the tuning elements may be configured to be tunable to adjust impedance of the amplifiers.
One or more of the tuning elements may be configured to be operated as a quarter-wave shunt switch.
The receive amplifier and the transmit amplifier may include a monolithic microwave integrated circuit component.
The receive amplifier may be a low-noise amplifier, and the transmit amplifier may be a high-power amplifier.
The outputs of the receive amplifier and transmit amplifier may each include an amplifier transistor, the inputs of the receive amplifier and transmit amplifier may each include a switch transistor, a gate of the amplifier transistor of the receive amplifier may be coupled to an electrode of the switch transistor of the receive amplifier, and a gate of the amplifier transistor of the transmit amplifier may be coupled to an electrode of the switch transistor of the transmit amplifier.
The gates of the switch transistors may be coupled to the system processor, which may be configured to manipulate impedance of the amplifiers by sending control signals to the switch transistors in accordance with either a transmit mode and a receive mode of the antenna system.
In accordance with another exemplary embodiment of the present invention, there is provided an antenna system including a system processor configured to send a transmit signal and receive a receive signal, an antenna element configured to radiate the transmit signal and detect the receive signal, a receive amplifier configured to amplify the receive signal and including an input coupled to the antenna element and including a switch transistor, and an output coupled to the system processor and including an amplifier transistor coupled to the switch transistor, and a transmit amplifier configured to amplify the transmit signal and including an input coupled to the output of the receive amplifier and including a switch transistor, and an output coupled to the input of the receive amplifier and including an amplifier transistor coupled to the switch transistor of the transmit amplifier, wherein the system processor is configured to alternately operate the amplifiers as signal switches according to control signals delivered to gates of the switch transistors.
In accordance with yet another exemplary embodiment of the present invention, there is provided an amplifier including an amplifier transistor, and a switch transistor, wherein the amplifier is configured to be switched on and off by controlling bias voltages of the transistors.
The transistors may be configured to have the bias voltages controlled by a control signal delivered to a gate of the switch transistor.
An electrode of the switch transistor may be coupled to a gate of the amplifier transistor, and a gate signal may be sent to the gate of the amplifier transistor in accordance with the control signal.
Accordingly, embodiments of the present invention allow for TR systems of improved performance and reduced size and cost and for an amplifier that may be operated as a switch.
The accompanying drawings, together with the specification, illustrate exemplary embodiments of the present invention, and, together with the description, serve to explain aspects of embodiments of the present invention. The above and other features and aspects of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:
A switch used in a TR chip of an electronically scanned antenna array system may be implemented as a separate component from the amplifier design of the transmit and receive amplifiers used in the TR system. Accordingly, switches are often designed in isolation from the design of the amplifier, and integrated only after the switches are individually optimized.
Benefit may be realized by designing the switches to be part of the same circuit that includes the amplifiers used to amplify the transmit signals and receive signals, and by merging various elements of corresponding switches and amplifiers, thereby enhancing performance of the antenna array system with minimal disadvantage.
Referring to
The receive amplifier 30 may operate as a low-noise amplifier (LNA) while the TR system 10 is in a receive mode. While in the receive mode, an impedance of a transmit path through the transmit amplifier 40 is high, and the transmit path operates as an “open” circuit. In order to match impedance with an input of the receive amplifier 30, TR switch parasitics may be utilized at the input 32 of the receive amplifier 30. When the TR system 10 of the present embodiment is operated in a transmit mode, the transmit amplifier 40 may operate as a high-power amplifier. While in the transmit mode, impedance of a receive path through the receive amplifier 30 is high, and the receive path operates as an “open” circuit.
The arrows 3 and 4 of
Referring to
Similarly, when the TR system 10 is in a transmit mode, the impedance measured from line 112 of the transmit amplifier 40 is a nominal impedance, allowing an electrical signal to pass therethrough, such as a transmit signal from the system processor 100 to the antenna 20. When the TR system is in a receive mode, the impedance of line 112 of the transmit amplifier 40 is high, and electrical signals along the transmit path are effectively blocked by the transmit amplifier 40.
The switch transistor 102 may be operated by a TR control signal delivered to a gate of the switch transistor 102, which may be a digital signal sent via the TR state line 130, thereby causing the switch transistor 102 to operate as a signal switch. Furthermore, an electrode of the switch transistor 102 may be coupled to a gate of an amplifier transistor at an output side 31, 41 of the amplifier 30, 40, according to embodiments of the present invention, whereby operation of the switch transistor 102 delivers a gate signal to the amplifier transistor via the gate line 131. The switch network parasitics of the inputs 32 and 42 may be designed to effectively match the topology of the amplifiers 30 and 40.
Accordingly, benefit may be realized by an amplifier that may be operated as a signal switch and by a TR system that obviates the need for switch or circulator circuitry by utilizing design of receive and transmit amplifiers of embodiments of the present invention.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that features of different embodiments may be combined to form further embodiments, and that various changes in form and details may be made therein, without departing from the spirit and scope of the present invention as defined by the following claims and their equivalents.
