MXPA00004580A - Monolithic high frequency antenna switch - Google Patents

Abstract

An antenna switch (101) for selectively connecting an output differential signal pair (190, 200) of an output power amplifier (110) to a single-ended signal (170) of an antenna (130) when transmitting and selectively connecting an input differential signal pair (210, 220) of a low noise input amplifier (120) to the single-ended signal (170) of the antenna (130) when receiving. A first balun (140) having a single ended-signal (160) connected to an antenna (130) connects a first (190) and second (200) output differential signal to a power output amplifier (110). A second balun (150) havinga single-ended signal (180) connected to the antenna (130) connects a first (210) and second (220) input differential signal to a low noise input amplifier (120). A first diode (230) selectively shorts the first output differential signal (190) to the second output differential signal (200) of the first balun (140) when receiving and a second diode (240) selectively shorts the first input differential signal (210) to the second input differential signal (220) of the second balun (150) when transmitting.

Description

HIGH FREQUENCY MONOLITHIC ANTENNA SWITCH FIELD OF THE INVENTION Technical Field of the Invention The present invention pertains generally to switching mechanisms for selectively connecting a power output amplifier or a low noise input amplifier from a transceiver to an anteha and, more particularly, to an antenna switch capable of operation at high frequencies that selectively connects differential signals of either an output power amplifier or differential signals of a low noise input amplifier of a radio transceiver to an antenna.

Description of Related Art When a single antenna is connected to a radio transceiver, a mechanism is required to selectively connect a transceiver output a. the antenna while isolating a transceiver input from the antenna during transmissions to selectively connect the transceiver input to the antenna while isolating the transceiver output from the antenna during receptions. In the past, the input and output signals from the transceiver have typically been designed in a single-ended, fifty-ohm environment with various methods available to provide switching functionality. For example, a Field Effect Transistor (FET) 'is incorporated into a single-pole double reversal circuit configuration to selectively connect the signals from a single end to the antenna depending on whether the transceiver is transmitting or receiving. x Even though Field Effect Transistors in a single-pole double-inversion circuit configuration and other switching mechanisms are capable of incorporating into a single integrated circuit chip along with the transceptor, their operation is limited to relatively high frequencies. low. Operation at higher frequencies typically requires the use of discrete PIN diodes or expensive Gallium Arsenide transistors to perform the switching function. For example, a commonly known technique uses a PIN diode in combination with a quarter-wavelength transmission line to selectively transform a short circuit into an open circuit and vice versa to selectively connect and disconnect the antenna to either the amplifier. energy output or the low noise input amplifier of the transcept.

Currently, there are increased demands to reduce the size of radio equipment, particularly in the radio telephone industry. To reduce the size of the radio equipment, more and more functionality is being incorporated into a single integrated circuit chip.As more functionality is integrated into the single integrated circuit, however, the interference between different functional blocks increases. reduce the interference, the signals that run between components are guided as differential signals instead of signals from a single end.Therefore, to incorporate an antenna switch "in tablet" requires a mechanism to connect a pair of output signal differential of the power output amplifier and a signal pair 'differential input of the low noise amplifier to a single-ended signal of the antenna.Also, the antenna switch needs to operate at relatively high radio frequencies used by many radio phones currently found and that will appear in the future, these radio frequencies may be in excess of two gigahertz. It would be advantageous, therefore, to design. an antenna switch for selectively connecting a differential output signal pair of a power output amplifier and a differential input signal pair of a low noise input amplifier of a transceiver to a signal of a single end of a antenna. It would also be advantageous if the antenna switch operated at frequencies above two gigahertz and is capable of integration into a single-chip integrated circuit, particularly a Bipolar Complementary Metal Oxide Semiconductor, with the transceiver. It would still be further advantageous if the antenna switch were economical to manufacture, SUMMARY OF THE INVENTION The present invention comprises an antenna switch for selectively connecting a differential signal signal output from an output power amplifier to a signal from a single end of an antenna when selectively transmitting and connecting a pair of signals. differential input signal from a low noise input amplifier to the signal from a single end of. the antenna when it receives. A single-ended signal of a first balanced-unbalanced transformer is electrically connected to an antenna and a first and second differential signals of the balanced-unbalanced transformer are electrically connected to a power output amplifier.

A single-ended signal of a second balanced-unbalanced transformer is electrically connected to the antenna and a first and second difference signals of the second balanced-unbalanced transformer are electrically connected to a low noise input amplifier. A first diode selectively shorts the first differential signal to the second differential signal of the first balanced-unbalanced transformer when the transceiver is receiving, resulting in an open circuit in the first balanced-unbalanced transformer. In this way, the single-ended signal is isolated from the first and second differential signals of the first balanced-unbalanced transformer. Likewise, . a second diode selectively shorts the first differential signal to the second differential signal of the second balanced-unbalanced transformer when the transceiver is transmitting resulting in an open circuit in the second balanced-unbalanced transformer. In this way, the single-ended signal is isolated from the first and second differential signals of the second balanced-unbalanced transformer. A preferred diode for use in the present invention is a Bipolar Complementary Metal Oxide Semiconductor period used for electrostatic protection on integrated circuit pads.

BRIEF DESCRIPTION OF THE DRAWINGS For a more complete understanding of the present invention, reference is made to the following detailed description, taken in conjunction with the accompanying drawings, wherein, Figure 1 is a functional block diagram of a antenna switch circuit of the present invention.

DETAILED DESCRIPTION OF THE MODALITIES Referring now to Figure 1, a functional block diagram of a circuit for implementing an antenna switch is illustrated. A transceiver 100 comprises a power output amplifier 110 for transmitting an output signal and a low noise input amplifier 120 for receiving an input signal. The power output amplifier 110 and the low noise input amplifier 120 are electrically connected to an antenna 130 via an antenna switch 101. In a preferred embodiment, the transceiver 100 and the antenna switch 101. are manufactured as a single integrated semiconductor component. The antenna switch 101 includes a first balanced-unbalanced transformer 140 and a second balanced-unbalanced transformer 150 respectively connecting the power output amplifier 110"and the low noise input amplifier 120 to the antenna 130. A port 160 of Single-ended signal from the first balanced-unbalanced transformer 140 is electrically connected to a single-ended signal port 170 of the antenna 130, Also, a single-ended signal port 180 of the second balanced-unbalanced transformer 150 is connected electrically to the single-ended signal port 170 of the antenna 130. The output of the power output amplifier 110 is electrically connected to the first balanced-unbalanced transformer 140 via a differential output signal pair comprising a first signal 190 output differential and a second 200 differential output signal. , the input of the low noise input amplifier 120 is electrically connected to the second balanced-unbalanced transformer 150 via a differential input signal pair comprising a first input differential signal 210 and a second input differential signal 220.

A first diode 230 is electrically connected between the first output differential signal 190 and the second output differential signal 200. Although any orientation of the first diode 230 can be accommodated by applying the appropriate voltages to the cathode and anode of the diode, in the preferred embodiment of the present invention, the cathode of the first diode 230 is electrically connected to the first differential signal 190"of output and anode in the first diode 230 is electrically connected to the second output differential signal 200. A second diode 240 is electrically connected between the first input differential signal 210 and the second input differential signal 220, similar to the first diode 230, any orientation The second diode 240 can be accommodated, however, in the preferred embodiment of the present invention, the anode of the second diode 240 is electrically connected to the first input differential signal 210 and the cathode of the second diode 240 is electrically connected to the second diode 240. 220 input differential signal, The construction and use of the transformed ores 140 and 150 balanced-unbalanced used in. the present invention with well-known in the industry. As an example, the first balanced-unbalanced transformer 140 and the second balanced-unbalanced transformer 150 comprise a resonance loop created by a first inductor 300, a first capacitor 308, a second inductor 305 and a second capacitor 315. A shunt The central 320 is electrically connected to an appropriate voltage such as the power supply voltage Vcc or ground to produce an appropriate reference voltage for use in polarizing the first diode 230 and the second diode 240. In the preferred embodiment, the bypass 320 The center of the first balanced-unbalanced transformer 140 is connected to Vcc, while the central branch 320 of the second balanced-unbalanced transformer 150 is connected to ground. The values of the components and the circuit configurations used in the balanced-unbalanced transformers 140 and 150 are selected based on a desired operating frequency of the transmitted and received signals. Additionally, the direct current block capacitors 250, whose values are also selected based on the desired operating frequency of the transmitted and received signals, are included in the block direct current signals. even though the present invention is applicable to all operating frequencies, the advantages of the present invention are particularly relevant at high frequencies where there is no economical "pill" solution. The first balanced-unbalanced transformer 140 is designed to resonate at the desired operating frequency of the transmitted and received signal. Under these conditions, a short circuit between the first output differential signal 190 and the second output differential signal 2 * D0 of the first balanced-unbalanced transformer 140 results in an open-circuit condition in the signal port 160 of a single end. . The open circuit condition isolates the first output differential signal 190 and the second output differential signal 200 from the single-ended signal port 160, thereby isolating the antenna power output amplifier 110. As will be described, the present invention exploits this property of the balanced-unbalanced transformers to effect the antenna switch, Also, the second, balanced-unbalanced transformer 150 is designed to resonate at the desired operating frequency of the transmitted and received signal and a short between. the first input differential signal 210 and the second input differential signal 220 of the second balanced-unbalanced transformer 150 result in an open-circuit condition in the single-ended signal port 180. The open cir- cuit condition isolates the first input differential signal 210 and the second input differential signal 220 from the single-ended signal port 180 thereby isolating the low noise input amplifier 120 from the antenna 130. To isolate the low noise input amplifier 120 of the antenna 130 during transmissions, a controller 300 applies a forward bias voltage, such as a power supply voltage Vcc, to the anode of the second diode 240 through a control signal line 310. The power supply voltage Vcc is of forward bias since the cathode of the second diode 240 is connected to ground through the center branch 320 of the second balanced-unbalanced transformer 150. The control line 310 also includes a limiting resistor 400. of current, even when separate control signal lines 310 could be used to apply separate polarization voltages to the first diode 230 and the second diode 240, a single signal control line 310 and a single bias voltage is used in the preferred of the present invention. Therefore, the control signal line 310 is also electrically connected to the cathode of the first diode 230. In this way, when the controller 300 applies a forward bias voltage Vcc to the anode of the second diode 240, it is at the same time applying a reverse bias voltage to the cathode of the first diode 230 since the anode of the first diode 230 is connected to the power supply voltage Vcc through the central branch 3 ^ 0 of the first balanced-unbalanced transformer 140, the voltage of forward bias through the second diode 240 results in a short circuit between the first input differential signal 210 and the second input differential signal 220, which in turn results in an open-circuit condition in the signal port '180 of a single end of the second balanced-unbalanced transformer 150, thus isolating the first differential input signal 210 and the second one the differential input 220 of the gate 170. signal from a single end of the antenna 130. At the same time, the controller 300 is applying a reverse bypass voltage through the first diode -230, 'The reverse bias voltage through the first diode 230 creates the equivalent of an open circuit through the first diode 230 and the first balanced-unbalanced transformer 140 operates in a normal manner with the output differential signal pair being electrically connected to the antenna 130 through the first balanced-unbalanced transformer 140. In a similar way, to isolate the power output amplifier 110 from the antenna 130 during the receptions, the controller 300 applies voltage to the cathode of the first diode 230 which places * the first diode 230 in a forward derived state. For example, by connecting the control signal line 310 to ground, the controller applies a lead derivation voltage to the first diode 230 since the anode of the first diode 230 is connected to the supply voltage Vcc of power through the lead 320 central of the first balanced-unbalanced transformer 140. The forward tap voltage across the first diode 230 results in a short circuit between the first differential signal 190, the output signal and the second differential output signal 200, which in turn results in an open circuit condition in the gate 160 Single-ended signal from the first balanced-unbalanced transformer 140, thereby isolating the first output differential signal 190 and the second output differential signal 200 from the signal port 170 of a single end of the antenna 130, At the same At the time, the controller 300 is applying a reverse bias voltage across the second diode 240 through the control signal signal 310. The reverse tap voltage through the second diode 240 creates the equivalent of an open circuit through the second diode 240 and in this way, the second balanced-unbalanced transformer 150 operates in a normal manner with the differential input signal pair being electrically connected to the antenna 130 through the second balanced-unbalanced transformer 150. The preferred embodiment of the present invention also includes inductive low pass filters 312• Inductive low pass filters serve to isolate the first differential signal 190 from the first differential input signal 210. It is also understood that even when the voltage Vcc of power supply and ground are used to forward-drift and reverse-reverse the first diode 230 and the second diode 240, any voltages which polarize forward and reverse the diodes can be used. To operate at relatively high frequencies, for example greater than two gigahertz, 'the first diode 230 and the second diode 230 require specific operating characteristics,' An ideal diode for use, as the first and second diodes 2_30 and 240 have the following characteristics; a resistance -r "of low series during the operation in a derived state in advance, a time 1 / t of prolonged transit and a capacitance CJO of joint derived in low reverse. Even when expensive semiconductor devices such as Gallium Arsenide (GaS) could be used to build an integrated circuit chip that incorporates the antenna switch and the transceiver, such a device would be prohibitively expensive. In the preferred embodiment of the present invention, an economic diode that fulfills these requirements is manufactured by a manufacturing process. of Bipolar Complementary Metal Oxide Semiconductor (BICHES). Although not used as a circuit breaker, the diodes currently used for Electrostatic Discharge (ESD) protection in bipolar complementary metal oxide semiconductors have the desired characteristics. For example, in the Philips Qubic 1 silicon chip manufacturing process, an electrostatic discharge protection diode with catalog number DB100W has a resistance rs in series equal to three ohms * in the forward derivative state, at equal to five nanoseconds and a CJO capacitance of reverse bypass board equal to one hundred and twenty six femtofarads. These values are sufficient for operation in the preferred embodiment of the present invention at frequencies above three hundred megahertz. In the reverse polarization state, this diode has a joint capacitance equal to one hundred and twenty-six femtof radii. Additional information regarding the design and operation of these electrostatic discharge protection diodes can be found in the Philips Qubic 1 or other design manual. Similar bipolar complementary metal oxide semiconductor design manuals. In addition to operating at the desired frequencies, bipolar complementary metal oxide semiconductor electrostatic discharge protection diodes of this type are inexpensive to manufacture and are easily integrated into an integrated circuit chip with other functionality of the transceiver, even when the use of bipolar complementary metal oxide semiconductor diodes for electrostatic discharge protection is well known, its use as a diode to provide high-speed "on-chip" switching functionality has not been previously taught in. the industry. Although a preferred embodiment of the method and apparatus of the present invention has been illustrated in the accompanying Drawing, and has been described in the above Detailed Description, it is understood that the invention is not limited to the described embodiment, but is capable of numerous new provisions, modifications and substitutions without abandoning the spirit of the invention as set forth and defined by the following claims. '"*

Claims (8)

1. CLAIMS: 1. An antenna switch for isolating an output amplifier of an antenna, comprising: a balanced-unbalanced transformer having a single-ended signal electrically connected to the antenna and a first and second output differential signal electrically connected to the amplifier departure; and an element for selectively short-circuiting the first differential output signal to the second output differential signal of the balanced-unbalanced transformer when the output amplifier of the antenna is isolated. 2, - The antenna switch according to claim 1, wherein the element for selectively short-circuiting the first differential output signal to the second output signal of the balanced-unbalanced transformer comprises: a diode electrically connected between the first and the second second output differential signal of the first balanced-unbalanced transformer; and an element for forwarding the diode when the output amplifier of the antenna is isolated. 3. - An antenna switch -to isolate "an input amplifier of an antenna, comprising: a balanced-unbalanced transformer having a signal from a single end electrically connected to the antenna and a first and second differential input signal electrically connected - to the input amplifier, and an element for selectively short-circuiting the first differential input signal to the second input differential signal of the balanced-unbalanced transformer when the input amplifier is isolated from the antenna. with claim 3, wherein the element for selectively short-circuiting the first differential input signal to the second differential input signal of the balanced-unbalanced transformer comprises: a diode electrically connected between the first and the second differential input signal of the balanced transformer - unbalanced, and an element pa To polarize the diode in advance when the input amplifier of the antenna is isolated. 5. An antenna switch comprising: a first balanced-unbalanced transformer having a single-ended signal electrically connected to an antenna and a first and second output differential signal electrically connected to a power output amplifier; a second balanced-unbalanced transformer electrically connected to the antenna and a first and second input differential signal electrically connected to a low noise input amplifier; an element for selectively short-circuiting the first differential output signal to the second output differential signal of the first balanced-unbalanced transformer when it receives; and an element for selectively short-circuiting the first input differential signal to the second input differential signal of the second balanced-unbalanced transformer when transmitting. 6. The antenna switch according to claim 5, wherein the element for selectively short-circuiting the first differential output signal to the second output differential signal of the first balanced-unbalanced transformer comprises: a first diode electrically connected between the first and the second output differential signal of the first balanced-unbalanced transformer; Y . an element for advancing polarization the first diode when receiving and reverse polarizing the first diode when transmitting; and further wherein the element for selectively short-circuiting the first differential input signal to the second input differential signal of the second balanced-unbalanced transformer comprises: a second diode electrically connected between the first and the second input differential signal of the second balanced transformer -unbalanced; and an element for reverse polarizing the second diode when it receives, and forward polarization _ the second diode when transmitting. 7. The antenna switch according to claim 6, wherein the element for polarizing the first diode and the element for polarizing the second diode comprises a controller that selectively applies a polarized voltage in advance to an anode of the first diode and a reverse polarized voltage to an anode of the second diode when it receives and applies a reverse bias voltage to the anode of the first diode y. a forward bias voltage to the anode of the second diode when transmitting. 8. An antenna switch according to claim 7, wherein the element for polarizing the first diode comprises a central branch of the first balanced-unbalanced transformer that electrically connects a direct current energy supply voltage Vcc to a cathode of the first diode, the central branch of the first balanced-unbalanced transformer to provide a reference voltage to the cathode of the first diode and wherein, in addition, the element for polarizing the second diode further comprises a central branch in the second balanced-unbalanced transformer that electrically connects a direct current earth voltage to a cathode the second diode, the central branch of the second balanced-unbalanced transformer to provide a reference voltage to the cathode of the second diode 9. The antenna switch according to claim 6, in where the first diode and the second diode or they are transistors of gallium arsenide. 10, - The antenna switch according to claim 6, wherein the first diode and the second diode are bipolar complementary metal oxide semiconductor diodes. 11, - The antenna switch 'according to claim 10, wherein the first diode and the second diode are bipolar complementary metal oxide semiconductor electrostatic discharge protection diodes. SUMMARY OF THE INVENTION An antenna switch (101) for selectively connecting a pair (190, 200) of differential output signal of an output power amplifier (110) to r. a signal (170) of a single end of an antenna (1 = 30) when transmitting and selectively connecting a differential input signal pair (210, 220) of a low noise input amplifier (120) to the signal ( 170) of a single end of the antenna (130) when it receives. A first balanced-unbalanced transformer (140) having a single-ended signal (160) connected to an antenna (130) connects a first (190) and a second (200) differential, output signal to an amplifier (110) of energy output. A second balanced-unbalanced transform (150) having a signal (180) of a single end connected to the antenna (130) connects a first (210) and a second (220) differential input signal to an amplifier (120) low noise input. A first diode (230) selectively shorts the first output differential signal (190) to the second output differential signal (200) of the first balanced-unbalanced transformer (140) when it receives and a second diode (240) selectively shorts the first signal (210) input differential to the second input signal (220) differential input of the second balanced (unbalanced) transformer (150) when transmitting,