KR20040051479A - Rf front-end for dual-band wireless transceiver module - Google Patents

Abstract

PURPOSE: An RF front end of a dual-mode band wireless transceiver is provided to be supplied for a dual-mode wireless transceiver module, and to supply a dual-mode RF front end having an antenna select diversity for both transmission path and receiving path. CONSTITUTION: An RF front end adopted within a dual-mode transceiver module connects the first and second dual-mode band antennas(40a,40b), and consists of the first and second signal receiving paths for receiving an RF signal in two different frequency bands, the first and second signal transmission paths for transmitting the RF signal in two different frequency bands, and a switch unit for connecting the first and second dual-mode band antennas(40a,40b) with the first and second signal transmission and receiving paths. The switch unit is composed of a DPDT(Dual Pole Dual Throw) switch(31) and two SPDT(Single Pole Dual Throw) switches(32,33).

Description

RF FRONT-END FOR DUAL-BAND WIRELESS TRANSCEIVER MODULE}

This application is related to another pending US patent application entitled “RF FRONT-END OF DUAL-MODE WIRELESS LAN MODULE” with application number 10 / 225,808, filed Aug. 21, 2002. Partial serial application of a pending US patent application entitled "RF FRONT-END FOR DUAL-MODE WIRELESS LAN MODULE" with application number 10 / 226,006.

The present invention relates to a radio frequency (RF) front end design, and more particularly, to an RF front end employed in a dual band radio transceiver module.

There are a number of two-mode wireless communications products currently available on the market, such as two-mode cellular phones, two-mode wireless LAN (WLAN) cards, and access points (APs).

RF front-end design is the key to success in designing dual-mode wireless transceiver modules. One problem with RF front-end design is how to design the antenna selection diversity function. In general, since the transmitted signal is much stronger than the received signal, antenna selection diversity for the receiver is more important than for the transmitter. Thus, most designs have antenna select diversity for the receiver, but no antenna diversity for the transmitter. Antenna diversity for the receiver allows the wireless transmission module to select a better performing antenna for the received signal. Since the transmitter does not have antenna diversity, there is a small insertion loss in the transmission path. By the way, such a design usually connects the transmission path directly to the antenna and results in difficulty in impedance matching.

Due to the influence of the operating environment, the antenna diversity function in the transmission path can help to improve the quality of the transmission signal. However, adding antenna diversity functionality for the transmitter requires adding more control components, which increases the insertion loss of the transmission path.

Therefore, RF frontends with antenna diversity for both transmitters and receivers and smaller insertion losses in both transmitters and receivers of dual-mode wireless communication modules are desirable to overcome the disadvantages described above.

It is a primary object of the present invention to provide a radio frequency (RF) front end for a dual mode radio transceiver module.

It is another object of the present invention to provide a dual mode RF front end with antenna selection diversity for both transmit and receive paths.

1 is a block diagram of a dual mode WLAN (WLAN) including an RF front end in accordance with the present invention;

FIG. 2 is a schematic diagram illustrating an example of an implementation of a switching unit of the RF front end of FIG. 1.

An RF front end according to an embodiment of the present invention is employed in a dual mode transceiver module, includes first and second dual band antennas, and includes a first and a second for receiving an RF signal in two different frequency bands. Connecting two signal reception paths, first and second signal transmission paths for transmitting RF signals in two different frequency bands, and first and second dual band antennas and first and second signal transmission and reception paths; It includes a switch unit. The switch unit includes a dipole double throw (DPDT) switch and two monopole double throw (SPDT) switches and performs antenna selection for both the first and second transmission paths and the first and second reception paths.

Other object advantages and novel forms of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.

Embodiment

1 and 2, an 802.11a / b dual mode wireless LAN (WLAN) module includes two main parts: a radio frequency (RF) part and a baseband part. The RF unit includes two dual band antennas 40a and 40b, an RF front end 30 and an RF integrated circuit (IC: 20). The baseband portion includes an interface circuit (without reference numerals) to the baseband (BB) IC 10 and the RFIC 20. The baseband portion includes an interface (not shown) for electrically connecting with the laptop computer 600.

Typically, the coupling between the RFIC 20 and the BBIC 10 is achieved based on a known combination of 802.11a / b chipset solutions, and the coupling between the BBIC 10 and the interface is known to those skilled in the art, Detailed descriptions of these couplings are omitted herein.

The dual band antennas 40a and 40b operate in the 2.4 to 2.4835 GHz frequency band and the 5.15 to 5.825 GHz frequency band. The RFIC 20 transmits a signal to the dual band antennas 40a and 40b via the RF front end 30 and receives the signal.

The RF front end 30 has three switches 31-33, four filters 101-104, four baluns 201-204, two power amplifiers 301, 302: PA, three logic control units. (34-36). Three switches 31-33 control the diversity and transmit / receive functions of the dual band antennas 40a and 40b. Three logic control units 34-36 control the ON / OFF states of the three switches 31-33 and the PAs 301,302.

Switch 31 is a bipolar double throw (DPDT) switch, pins 4 and 6 connected to two dual band antennas 40b and 40a, respectively, and pins 12 and 10 connected to switches 32 and 33, respectively. It is configured with. The switches 32 and 33 are single pole double throw (SPDT) switches. The switch 32 connects the pin 12 of the switch 31 with a first frequency band signal transmission path, which is optionally provided with a ballon 203, a PA 301, and a filter 103, or 201) and a filter 101, and the first frequency band signal receiving path. Conversely, the first frequency band may be, for example, the 2.4-2.4835 GHz band, and the second frequency band may be the 5.15-5.825 GHz band. Filters 101 and 102 are band pass filters (BPFs), and filters 103 and 104 are low pass filters (LPFs).

The signal received from the dual band antennas 40a and 40b is configured with the signal f1 Rx (2.4-2.4835 GHz) and the signal f2 Rx (5.15-5.825 GHz) selected by the combination of the switches 31-33. The signal f1 Rx is filtered by the BPF 101, and the filtered signal f1 Rx is transmitted to the RFIC 20 via the balun 201. Similarly, the signal f2 Rx is filtered by the BPF 102, and the filtered signal f2 Rx is delivered to the RFIC 20 via the balun 202.

The signal sent to the dual band antennas 40a and 40b for transmission is configured with a signal f1 Tx (2.4-2.4835 GHz) and a signal f2 Tx (5.15-5.825 GHz) generated by the RFIC 20. The signal f1 Tx is sent to the PA 301 via the balun 203. The signal f1 Tx is amplified by the PA 301 and then filtered by the LPF 103, and the filtered signal f1 Tx is routed through the switches 31 and 32 to the dual band antennas 40a and 40b. All. Similarly, the signal f2 Tx is first sent to the PA 302 via the balun 204. The signal f2 Tx is amplified by the PA 302 and then filtered by the LPF 104, and the filtered signal f2 Tx is routed through the switches 31 and 33 to the dual band antennas 40a and 40b. All.

The # 1 logic control unit 35 is controlled by the antenna diversity control signal ANT_Control from the BBIC 10 and outputs signals V1 and V2 for controlling the switch 31. When the voltage level of the signal V1 is low and the voltage level of the signal V2 is high, the pins 4 and 12 are connected and the pins 6 and 10 are connected; When the voltage level of the signal V1 is high and the voltage level of the signal V2 is low, the pins 4 and 10 are connected and the pins 6 and 12 are connected. Therefore, the antenna selection function of the RF front end 30 is achieved by the switch 31 and the # 1 logic control unit 35.

The # 2 logic control unit 34 is controlled by the transmit / receive control signal Tx_Rx_Control from the BBIC 10 and controls the switches 32 and 33 to be connected to the transmission path and the reception path. When the transmit path is ON, the receive path is OFF; When the receive path is ON, the transmit path is OFF. By ensuring that only the transmit path and receive path are connected at the same time, good shielding between the transmit path and the receive path is ensured.

# 3 logic control unit 36 controls two PAs 301 and 302, which itself includes a PA power control signal PA_PWR_Control and a frequency band control signal BAND_Control and a Tx_Rx Control signal from BBIC 10; Is controlled by a combination of. When the PA 301 is ON, the PA 302 is OFF; When the PA 302 is ON, the PA 301 is OFF. Since only one PA is enabled at the same time, when one transmission path is selected, the associated PA is enabled to transmit the signal, and the PAs in the second transmission path are disabled.

When the 802.11a / b dual mode WLAN module transmits a signal, the switches 32 and 33 connect the transmission paths under the control of the Tx_Rx_Control signal, and the # 3 logic control unit 36 enables the corresponding transmission paths. Select which PAs 301 and 302 are turned on.

When the 802.11a / b dual mode WLAN module receives a signal, the switches 32 and 33 connect the receive paths under the control of the Tx_Rx_Control signal.

The 802.11a / b dual mode WLAN module is mounted within the laptop computer 600, and the two dual band antennas 40a, 40b are located in various locations within the laptop computer 600. Thus, the two dual band antennas 40a and 40b have various receive / transmit capabilities for incoming / outgoing signals. The ANT_Control signal controls switch 31 to select dual band antennas 40a and 40b with good reception / transmission performance.

Using this design of antenna selection function, the receive path or transmit path is enabled at a given time. Thus, the receive path is well shielded from the transmit path. Moreover, since only two switch control stages are used on each transmit or receive path, lower insertion loss is achieved within the transmit or receive path.

This design can be used not only for the RF front-end design for 802.11a / b dual mode WLAN modules, but also for the design of other dual band wireless transceiver modules for wireless communications devices such as cellular phones.

By the way, although the various features and advantages of the present invention have been described in the above detailed description with the detailed description of the structure and function of the present invention, the disclosed contents are only examples, and modifications in the shape, size and arrangement of parts are attached. To the full extent indicated by the broad general meaning of the terms in the appended claims, it may be made within the principles of the present alias.

As described above, according to the present invention, a dual mode RF capable of providing a radio frequency (RF) front end for a dual mode radio transceiver module and having antenna selection diversity for both a transmission path and a reception path Can provide a frontend

Claims (8)

A radio frequency (RF) front end adapted to be employed within a dual mode transceiver module having a first and a second dual band antenna, first and second signal transmission paths, and first and second signal reception paths, A bipolar double throw (DPDT) switch having first and second output pins and first and second input pins coupled to the first and second dual band antennas, respectively; A first single pole double throw (SPDT) switch coupling a second input pin and a first signal transmission and reception path of a dual mode transceiver module; And a second SPDT switch coupling the first input pin and the second signal transmission and reception path of the dual mode transceiver module. According to claim 1, Any one of the second output pin and the first input pin connected to the second output and the input pin connected to the first output and the input pin or the first output pin and the second input pin connected. And a first logic control unit for controlling the DPDT switch to select the radio frequency front end. 3. The apparatus of claim 2, further comprising a second logic control unit for controlling the first and second SPDT switches to enable either the first and second signal transmission paths or the first and second signal reception paths. Radio frequency front end, characterized in that configured to. An RF front end adapted to be employed in a dual mode transceiver module, First and second antennas, First and second signal receiving paths for receiving RF signals in two different frequency bands, First and second signal transmission paths for transmitting RF signals in two different frequency bands, And a switch unit connecting the first and second antennas with the first and second signal transmission and reception paths and performing an antenna selection function in both the first and second transmission paths and the first and second reception paths. Radio frequency front end, characterized in that. The apparatus of claim 4, further comprising: a DPDT switch coupled to the first and second antennas, a first SPDT switch connecting the DPDT switch and the first signal transmission and reception path, and a DPDT switch and the second signal transmission and reception path connecting the DPDT switch and the second signal transmission and reception path. And a second SPDT switch. 5. The radio frequency front end of claim 4, wherein each of the first and second signal transmission paths comprises first and second power amplifiers (PAs). 7. The radio frequency front end according to claim 6, further comprising a logic control unit for enabling either one of the first PA or the second PA. A radio frequency (RF) front end adapted to be employed within a dual mode transceiver module having a first and a second dual band antenna, first and second signal transmission paths, and first and second signal reception paths, A first switch having first and second output pins and first and second input pins coupled to the first and second dual band antennas, respectively; A second switch coupling the second input pin and the first signal transmission and reception path of the dual mode transceiver module; A third switch coupling the first input pin and a second signal transmission and reception path of the dual mode transceiver module; A first power amplifier connected to the first transmission path, And a second power amplifier connected to the second transmission path, And a transmit path and a receive path are mutually exclusively enabled, and a first power amplifier and a second power amplifier are mutually exclusively enabled.