CN103378870A - Communication device and radio frequency equalizer - Google Patents

Abstract

A radio frequency equalizer comprises a first resistor coupled to an input end, a second resistor coupled between the first resistor and an output end, a first capacitor, a first inductor, a first switch coupled to the input end, the first capacitor and the first inductor, a second switch coupled to the output end, the first capacitor and the first inductor, a second capacitor, a second inductor and a third switch coupled to the first resistor, the second capacitor and the second inductor. The first switch selectively couples the first capacitor or the first inductor to the input terminal according to a control signal. The second switch selectively couples the first capacitor or the first inductor to the output end according to the control signal. The third switch selectively couples the second capacitor or the second inductor to a connection point of the first resistor and the second resistor according to the control signal.

Description

Communication Devices and RF Equalizers

technical field

The invention relates to a radio frequency equalizer, in particular to a radio frequency equalizer capable of compensating the power flatness of radio frequency signals.

Background technique

Due to the advancement of the mobile communication system in recent years, it can provide various communication services, such as voice service, data service, and video service, in a manner that is not limited to the user's location. The general mobile communication system is a multiple access system, which means that multiple users can access the system at the same time and allocate appropriate wireless network resources to the users. The multiple access technologies used include: global mobile communication System (Global System for Mobile communications, GSM), code division multiple access system (Code Division Multiple Access, CDMA), wideband code division multiple access system (Wideband Code Division Multiple Access, WCDMA), and long term evolution (LongTerm Evolution, LTE) technology and so on. In addition, Long Term Evolution Advanced (LTE Advanced) is an enhanced technology developed according to the Long Term Evolution (LTE) standard.

In order to enable one mobile communication device to support multiple different communication technologies (eg, the above-mentioned GSM, CDMA, WCDMA, LTE, etc.), multi-mode mobile communication device design has gradually become the mainstream of the market. Since the frequency bands used by various communication technologies are different, the multi-mode mobile communication device must support a sufficiently wide frequency range, for example, a frequency range extending from 0.7 gigahertz (GHz) to 3 gigahertz (GHz).

However, due to the characteristics of the electronic components in the mobile communication device, under the same input power, the processed output power of the mobile communication device for radio frequency signals of different frequency bands may be different, resulting in different power levels of the radio frequency signals. flat phenomenon. FIG. 1a is a graph showing the output power of the RF signal versus frequency, which is an example of the output power of the RF signal decreasing as the frequency increases. FIG. 1b is another curve showing the output power of the RF signal relative to the frequency. This is an example of the output power of the RF signal increasing as the frequency increases. Both the power increase and decrease are one of the phenomena of the output power of the RF signal being uneven.

In order to solve the phenomenon that the output power of the radio frequency signal is not flat, the present invention proposes a radio frequency equalizer, which can effectively compensate the flatness of the output power of the radio frequency signal.

Contents of the invention

According to an embodiment of the present invention, a communication device includes a radio frequency transceiver, a radio frequency equalizer, a power amplifier, and a duplexer. The radio frequency transceiver is used for generating a plurality of radio frequency signals according to a plurality of baseband signals. The RF equalizer is coupled to the RF transceiver for receiving the RF signal and generating a plurality of equalized RF signals according to a control signal, wherein a frequency response corresponding to the RF equalizer is adjusted in response to the control signal. The power amplifier is coupled to the radio frequency equalizer for receiving the equalized radio frequency signal and amplifying the equalized radio frequency signal to generate a plurality of amplified radio frequency signals. The duplexer is coupled to the power amplifier for receiving the amplified radio frequency signal and transmitting the amplified radio frequency signal to an antenna.

According to another embodiment of the present invention, a radio frequency equalizer is used to receive a plurality of radio frequency signals, and generate a plurality of equalized radio frequency signals according to a control signal, including a first resistor, a second resistor, a first capacitor, The first inductor, the first switch, the second switch, the second capacitor, the second inductor and the third switch. The first resistor is coupled to an input terminal. The second resistor is coupled between the first resistor and an output terminal. The first switch is coupled to the input terminal, the first capacitor and the first inductor, and is used for selectively coupling the first capacitor or the first inductor to the input terminal according to a control signal. The second switch is coupled to the output terminal, the first capacitor and the first inductor, and is used for selectively coupling the first capacitor or the first inductor to the output terminal according to a control signal. The third switch is coupled to the first resistor, the second resistor, the second capacitor and the second inductor, and is used for selectively coupling the second capacitor or the second inductor to a connection between the first resistor and the second resistor according to a control signal point.

Description of drawings

Figure 1a is a graph showing the output power of an RF signal versus frequency.

Figure 1b is another graph showing RF signal output power versus frequency.

FIG. 2 is a block diagram showing a communication device according to an embodiment of the invention.

FIG. 3 is a block diagram showing a communication device according to another embodiment of the present invention.

FIG. 4 is a circuit diagram showing a radio frequency equalizer according to an embodiment of the invention.

FIG. 5 a is an equivalent circuit diagram showing a radio frequency equalizer according to an embodiment of the present invention when the control signal has a first state.

FIG. 5 b shows a frequency response curve of an RF equalizer according to an embodiment of the present invention.

FIG. 6 a is an equivalent circuit diagram showing the radio frequency equalizer according to an embodiment of the present invention when the control signal has a second state.

FIG. 6b shows a frequency response curve of an RF equalizer according to another embodiment of the present invention.

7 is a graph showing power versus frequency of an amplified RF signal output by a power amplifier after being compensated by an RF equalizer according to an embodiment of the present invention.

[Description of main component labels]

200, 300～communication device; 210, 310～baseband signal processing device;

220, 320～RF transceiver; 230, 430, 530, 630～RF equalizer;

240～power amplifier; 250～directional coupler;

260～duplexer; 270～antenna;

280, 380～power detector; 290～load;

501, 502, 601, 602～curve; C1, C2～capacitance;

Ctrl～control signal; IN～input terminal;

L1, L2～inductance; N1～connection point;

OUT～output terminal; R1, R2～resistance;

RX ~ receiving port; S1, S2, S3 ~ switch;

TX ~ transmission port.

Detailed ways

In order to make the manufacture, operation method, objectives and advantages of the present invention more obvious and easy to understand, several preferred embodiments are specifically cited below, together with the accompanying drawings, and are described in detail as follows:

Example:

FIG. 2 is a block diagram showing a communication device according to an embodiment of the invention. The communication device 200 may at least include a baseband signal processing device 210 , a radio frequency transceiver 220 , a radio frequency equalizer 230 , a power amplifier 240 , a directional coupler 250 , a duplexer 260 and an antenna 270 . The baseband signal processing device 210 is used for processing and generating the baseband signal. The baseband signal processing device 210 may include multiple hardware devices to perform baseband signal processing, including analog to digital conversion (analog to digital conversion, ADC)/digital to analog conversion (digital to analog conversion, DAC), gain (gain) adjustment, Modulation and demodulation, and encoding/decoding, etc. The baseband signal processing device 210 may further include a transmitting port TX for transmitting uplink (uplink) signals, and a receiving port RX for receiving downlink (downlink) signals.

The radio frequency transceiver 220 is used to process the radio frequency signal, which can receive the downlink radio frequency signal, and convert the radio frequency signal into a baseband signal for further processing by the baseband signal processing device 210, or receive from the baseband signal processing device 210 The baseband signal for the uplink and converts the baseband signal into a radio frequency signal for transmission. The radio frequency transceiver 220 may also include a plurality of hardware devices to perform the above radio frequency conversion. For example, the radio frequency transceiver 220 may include a mixer (mixer), which is used to multiply the base frequency signal by the oscillation used in the mobile communication system. A carrier at a transmission frequency of 900 MHz, 1800 MHz, or 1900 MHz for GSM, or 900 MHz, 1900 MHz, or 2100 MHz for UMTS, or 900 MHz, 2100 MHz for LTE , or 2600 MHz, or depending on the standards of other wireless access technologies.

The RF equalizer 230 is coupled to the RF transceiver 220 for receiving the uplink RF signal, and generates an equalized RF signal according to a control signal Ctrl and the received uplink RF signal. According to an embodiment of the present invention, the control signal Ctrl is generated by the power detector 280 to adjust a frequency response corresponding to the RF equalizer 230, so that the communication device 200 can compensate the output power of the RF signal through the RF equalizer 230 The phenomenon of unevenness (the following paragraphs will introduce the radio frequency equalizer 230 proposed by the present invention in more detail).

The power amplifier 240 is coupled to the RF equalizer 230 for receiving the equalized RF signal and amplifying the equalized RF signal to generate an amplified RF signal. The directional coupler 250 is coupled between the power amplifier 240 and the duplexer 260 to transmit most of the amplified RF signal to the duplexer 260 and feed back a part of the amplified RF signal to the power detector 280 . The directional coupler 250 may include an input port coupled to an output of the power amplifier 240, an output port coupled to an input of the duplexer 250, an output port coupled to a load 290 (typically a 50 ohm load). A signal isolation port and a coupling port for feeding back a part of the amplified radio frequency signal.

The duplexer 260 is coupled to the power amplifier 240 through the directional coupler 250 for receiving the amplified RF signal and transmitting the amplified RF signal to the antenna 270 . The amplified radio frequency signal is finally transmitted into the air through the antenna. In downlink signal processing, the duplexer 260 receives a downlink RF signal from the antenna 270 and transmits the received signal to the receiving port RX of the RF transceiver 220 .

According to an embodiment of the present invention, the power detector 280 is used to detect the power of the amplified RF signal, and generate the control signal Ctrl according to the power of the amplified RF signal. It should be noted that the power detector 280 can be implemented as an independent device, or integrated in the radio frequency transceiver 220 as shown in FIG. 2 , and the present invention is not limited to any implementation. In addition, when the power detector 280 is integrated in the radio frequency transceiver 220, the power detector 280 can also be an independent device, or can be implemented by an internal component (for example, a processor) of the radio frequency transceiver 220, the present invention It is not limited to any one embodiment.

According to another embodiment of the present invention, the power detector can also be integrated in the baseband signal processing device. FIG. 3 is a block diagram showing a communication device according to another embodiment of the present invention. The communication device 300 may at least include a baseband signal processing device 310 , a radio frequency transceiver 320 , a radio frequency equalizer 230 , a power amplifier 240 , a directional coupler 250 , a duplexer 260 and an antenna 270 . The introduction of the baseband signal processing device 310, radio frequency transceiver 320, radio frequency equalizer 230, power amplifier 240, directional coupler 250, duplexer 260 and antenna 270 can refer to the relevant description of FIG. 2 and will not be repeated here. .

In this embodiment, the power detector 380 is integrated in the baseband signal processing device 310 . The power detector 380 can also be an independent device, or can be implemented by components (eg, a processor) inside the baseband signal processing device 310 , and the present invention is not limited to any implementation. It should be noted that, in this embodiment, a part of the amplified RF signal fed back by the directional coupler 250 can be directly sent to the power detector 380 for power detection, or first down-converted by the RF transceiver 320, and then transmitted to the power detector 380 for power detection, and the present invention is not limited to any implementation.

According to an embodiment of the present invention, the power detector 280/380 is mainly used to detect the flatness of a curve of the power of the amplified RF signal versus frequency. For example, the power detector 280/380 can record radio frequency signals of different frequency bands (for example, different transmission frequency bands used by different communication technologies, or different transmission frequency bands used by the same communication technology, or others) after being amplified by the power amplifier 240 to obtain a power versus frequency curve of the amplified RF signal (for example, the curves shown in Figures 1a and 1b). After obtaining the curve of power versus frequency, the power detector 280/380 can further judge according to the curve whether the power of the amplified radio frequency signal increases or decreases as the frequency increases, so as to generate a corresponding control signal Ctrl to adjust the radio frequency equalization The frequency response of the device 230.

FIG. 4 is a circuit diagram showing a radio frequency equalizer according to an embodiment of the invention. The RF equalizer 430 may include resistors R1 and R2, capacitors C1 and C2, inductors L1 and L2, and switches S1, S2 and S3. The resistors R1 and R2 are coupled in series between the input terminal IN and the output terminal OUT of the RF equalizer 430 . The switch S1 is coupled between the input terminal IN of the radio frequency equalizer 430 , the capacitor C1 and the inductor L1 for selectively coupling one of the capacitor C1 or the inductor L1 to the input terminal IN according to the control signal Ctrl. The switch S2 is coupled between the output terminal OUT of the radio frequency equalizer 430 , the capacitor C1 and the inductor L1 for selectively coupling one of the capacitor C1 or the inductor L1 to the output terminal OUT according to the control signal Ctrl. Therefore, in response to different states of the control signal Ctrl, one of the capacitor C1 and the inductor L1 is coupled in parallel with the resistors R1 and R2 between the input terminal IN and the output terminal OUT. Likewise, the switch S3 is coupled between the resistors R1 and R2 , the capacitor C2 and the inductor L2 for selectively coupling the capacitor C2 or the inductor L2 to a connection point N1 of the resistors R1 and R2 according to the control signal Ctrl.

According to an embodiment of the present invention, when the power detector 280/380 judges that the power of the amplified radio frequency signal decreases as the frequency increases (for example, as shown in the curve of FIG. A logic high level state or a logic low level state) the control signal Ctrl is used to control the switching operation of the switches S1, S2 and S3, and then obtain the equivalent circuit diagram of the radio frequency equalizer as shown in FIG. 5a-.

As shown in FIG. 5 a , when the control signal Ctrl has the first state, the equivalent circuit of the radio frequency equalizer 530 includes resistors R1 and R2 , capacitor C1 and inductor L2 . The capacitor C1 and the resistors R1 and R2 are coupled in parallel between the input terminal IN and the output terminal OUT, and the inductor L2 is coupled between the connection point N1 of the resistors R1 and R2 and a terminal (eg, a ground point). It should be noted that the inductor L1 is electrically isolated from the input terminal IN and the output terminal OUT, and the capacitor C2 is electrically isolated from the resistors R1 and R2.

FIG. 5 b shows a frequency response curve of an RF equalizer according to an embodiment of the present invention. The frequency response curve shown in FIG. 5b is the frequency response curve corresponding to the equivalent circuit of the radio frequency equalizer shown in FIG. 5a. As shown in the figure, the frequency response corresponding to the equivalent circuit of the RF equalizer 530 is a curve in which the insertion loss decreases as the frequency of the RF signal increases. Therefore, when the power detector 280/380 detects the amplified RF signal When the power of the signal decreases as the frequency increases, the control signal Ctrl can be set to have a first state, so as to compensate the unevenness of the output power of the radio frequency signal through the radio frequency equalizer 230 .

It should be noted that the capacitance value of the capacitor C1 and the inductance value of the inductor L2 can be adjusted according to the slope of the required frequency response to achieve the best compensation effect. According to an embodiment of the present invention, when the capacitance of the capacitor C1 and the inductance of the inductor L2 are smaller, a slope of a frequency response corresponding to the radio frequency equalizer is larger. For example, as shown in FIG. 5 b , the capacitance of the capacitor C1 and the inductance of the inductor L2 corresponding to the frequency response curve 502 are smaller than the capacitance of the capacitor C1 and the inductance of the inductor L2 corresponding to the frequency response curve 501 .

According to another embodiment of the present invention, when the power detector 280/380 judges that the power of the amplified radio frequency signal increases as the frequency increases (for example, as shown in the curve of FIG. , a logic low level state or a logic high level state) the control signal Ctrl is used to control the switching operation of the switches S1, S2 and S3, and then obtain the equivalent circuit diagram of the radio frequency equalizer shown in FIG. 6a-.

As shown in FIG. 6 a , when the control signal Ctrl has the second state, the equivalent circuit of the radio frequency equalizer 630 includes resistors R1 and R2 , capacitor C2 and inductor L1 . The inductor L1 and the resistors R1 and R2 are coupled in parallel between the input terminal IN and the output terminal OUT, and the capacitor C2 is coupled between the connection point N1 of the resistors R1 and R2 and an end point (eg, a ground point). It should be noted that at this time, the capacitor C1 is electrically isolated from the input terminal IN and the output terminal OUT, and the inductor L2 is electrically isolated from the resistors R1 and R2.

FIG. 6b shows a frequency response curve of an RF equalizer according to another embodiment of the present invention. The frequency response curve shown in FIG. 6b is the frequency response corresponding to the equivalent circuit of the radio frequency equalizer shown in FIG. 6a. As shown in the figure, the frequency response corresponding to the equivalent circuit of the RF equalizer 630 is a curve in which the insertion loss increases as the frequency of the RF signal increases. Therefore, when the power detector 280/380 detects the amplified RF signal When the power of the frequency increases gradually with the increase of the frequency, the control signal Ctrl can be set to have a second state, which is used to compensate the unevenness of the output power of the radio frequency signal through the radio frequency equalizer 230 .

It should be noted that the capacitance of the capacitor C2 and the inductance of the inductor L1 can be adjusted according to the slope of the required frequency response to achieve the best compensation effect. According to an embodiment of the present invention, when the capacitance of the capacitor C2 and the inductance of the inductor L1 are larger, a slope of the frequency response corresponding to the radio frequency equalizer is larger. For example, as shown in FIG. 6 b , the capacitance of the capacitor C2 and the inductance of the inductor L1 corresponding to the frequency response curve 602 are greater than the capacitance of the capacitor C2 and the inductance of the inductor L1 corresponding to the frequency response curve 601 .

7 is a graph showing power versus frequency of an amplified RF signal output by a power amplifier after being compensated by an RF equalizer according to an embodiment of the present invention. As shown in the figure, compared with FIG. 1a and FIG. 1b, in the embodiment of the present invention, the frequency response corresponding to the radio frequency equalizer is adjusted through the control signal Ctrl, so that the power of the amplified radio frequency signal relative to the frequency curve The flatness can be effectively increased, thus solving the phenomenon that the output power of the radio frequency signal is not flat.

The use of the ordinal numerals "first", "second", "third" and the like to modify elements in the claims does not in itself imply any priority, order of precedence, order of priority among elements, or method performed The sequence of steps is used only as a label to distinguish between different elements with the same name (with different ordinal numbers).

Although the present invention is disclosed above with preferred embodiments, it is not intended to limit the scope of the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, The scope of protection of the present invention should be defined by the appended claims.

Claims (15)

1. A communication device, comprising: a radio frequency transceiver, used for generating a plurality of radio frequency signals according to a plurality of baseband signals; a radio frequency equalizer, coupled to the radio frequency transceiver, for receiving the plurality of radio frequency signals, and generating a plurality of equalized radio frequency signals according to a control signal; a power amplifier, coupled to the radio frequency equalizer, for receiving the plurality of equalized radio frequency signals, and amplifying the plurality of equalized radio frequency signals to generate a plurality of amplified radio frequency signals; and a duplexer, coupled to the power amplifier, for receiving the amplified radio frequency signals and transmitting the amplified radio frequency signals to an antenna, A frequency response corresponding to the radio frequency equalizer is adjusted in response to the control signal. 2. The communication device according to claim 1, further comprising: a power detector, used to detect the power of the plurality of amplified radio frequency signals, and generate the control signal according to the power of the plurality of amplified radio frequency signals; and A directional coupler, coupled between the power amplifier and the duplexer, is used to feed back a part of the amplified radio frequency signals to the power detector. 3. The communication device according to claim 2, wherein the power detector is included in the radio frequency transceiver. 4. The communication device according to claim 2, further comprising: A baseband signal processing device is used to process and generate the plurality of baseband signals, wherein the power detector is included in the baseband signal processing device. 5. The communication device according to claim 1, wherein the radio frequency equalizer comprises: a first resistor coupled to an input terminal; a second resistor coupled between the first resistor and an output terminal; a first capacitor; a first inductance; a first switch, coupled to the input terminal, the first capacitor and the first inductor, for selectively coupling the first capacitor or the first inductor to the input terminal according to the control signal; a second switch, coupled to the output terminal, the first capacitor and the first inductor, for selectively coupling the first capacitor or the first inductor to the output terminal according to the control signal; a second capacitor; a second inductor; and a third switch, coupled to the first resistor, the second resistor, the second capacitor and the second inductor, for selectively coupling the second capacitor or the second inductor to the second capacitor according to the control signal A connection point between the first resistor and the second resistor. 6 . The communication device according to claim 5 , wherein a slope of the frequency response corresponding to the RF equalizer is larger when a capacitance value of the first capacitor and an inductance value of the second inductor are smaller. 7. The communication device according to claim 5, wherein when an inductance value of the first inductor and a capacitance value of the second capacitor are larger, a slope of the frequency response corresponding to the radio frequency equalizer is larger . 8. The communication device according to claim 2, wherein when the power detector detects that the power of the amplified radio frequency signals decreases as the frequency of the amplified radio frequency signals increases, the radio frequency equalizer The appliance has an equivalent circuit consisting of: a first resistor coupled to an input terminal; a second resistor coupled between the first resistor and an output terminal; a capacitor coupled between the input terminal and the output terminal; and An inductor is coupled between a connection point and an end point of the first resistor and the second resistor. 9. The communication device according to claim 2, wherein when the power detector detects that the power of the amplified radio frequency signals increases as the frequency of the amplified radio frequency signals increases, the radio frequency equalizer The appliance has an equivalent circuit consisting of: a first resistor coupled to an input terminal; a second resistor coupled between the first resistor and an output terminal; an inductor coupled between the input terminal and the output terminal; and A capacitor is coupled between a connection point and an end point of the first resistor and the second resistor. 10. The communication device according to claim 2 , wherein the power detector generates the control signal to adjust the frequency response corresponding to the RF equalizer to increase the power of the amplified RF signals relative to the The flatness of a curve of frequencies of amplified RF signals. 11. A radio frequency equalizer, used to receive a plurality of radio frequency signals, and generate a plurality of equalized radio frequency signals according to a control signal, comprising: a first resistor coupled to an input terminal; a second resistor coupled between the first resistor and an output terminal; a first capacitor; a first inductance; a first switch, coupled to the input terminal, the first capacitor and the first inductor, for selectively coupling the first capacitor or the first inductor to the input terminal according to the control signal; a second switch, coupled to the output terminal, the first capacitor and the first inductor, for selectively coupling the first capacitor or the first inductor to the output terminal according to the control signal; a second capacitor; a second inductor; and a third switch, coupled to the first resistor, the second resistor, the second capacitor and the second inductor, for selectively coupling the second capacitor or the second inductor to the second capacitor according to the control signal A connection point between the first resistor and the second resistor. 12. The radio frequency equalizer according to claim 11, wherein when the control signal has a first state, the first capacitor is coupled between the input terminal and the output terminal, and the first inductor and the input terminal and the output end are electrically insulated, the second inductor is coupled between a connection point and an end point of the first resistor and the second resistor, and the second capacitor is electrically insulated from the first resistor and the second resistor sex insulation. 13. The radio frequency equalizer according to claim 11, wherein when the control signal has a second state, the first inductor is coupled between the input terminal and the output terminal, and the first capacitor and the input terminal and the output end are electrically insulated, the second capacitor is coupled between a connection point and an end point of the first resistor and the second resistor, and the second inductor is electrically insulated from the first resistor and the second resistor sex insulation. 14. The radio frequency equalizer according to claim 11, wherein the smaller the capacitance value of the first capacitor and the inductance value of the second inductor, the larger the slope of a frequency response corresponding to the radio frequency equalizer . 15. The radio frequency equalizer according to claim 11 , wherein when an inductance value of the first inductor and a capacitance value of the second capacitor are larger, a slope of a frequency response corresponding to the radio frequency equalizer is higher. big.

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