CN111404574B - Intermediate frequency device applied to WLAN zero intermediate frequency transceiver system - Google Patents
Intermediate frequency device applied to WLAN zero intermediate frequency transceiver system Download PDFInfo
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- H—ELECTRICITY
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- 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
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- 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
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Abstract
The invention relates to an intermediate frequency device applied to a WLAN (wireless local area network) zero intermediate frequency transceiver system, belongs to the technical field of electronic circuits, and solves the problem of low reuse rate of the conventional device. The intermediate frequency device comprises a control component, a third-order/fifth-order filter and a multiplexer; when the zero intermediate frequency transceiver works in a transmitting mode, the control component controls the third-order/fifth-order filter to be switched to a third-order filter mode, and simultaneously controls the multiplexer to gate a transmitting channel, so that the third-order filter is connected in a transmitting link; when the zero intermediate frequency transceiver works in a receiving mode, the control component controls the third order/fifth order filter to be switched to a fifth order filter mode, and simultaneously controls the multiplexer to gate a receiving channel, so that the fifth order filter is connected in a receiving link. The switching between the third-order filter and the fifth-order filter is realized, and the reuse rate of the intermediate frequency device is improved.
Description
Technical Field
The invention relates to the technical field of electronic circuits, in particular to an intermediate frequency device applied to a WLAN zero intermediate frequency transceiver system.
Background
A method of multiplexing filters as shown in figure 1. The RX/TX control circuit of the method is connected with a multiplexing type filter circuit and a multiplexer, and the input end and the output end of the multiplexing type filter circuit are respectively provided with two multiplexers. Wherein the multiplexing-type filter is a first order filter. When the radio frequency transceiver is operated in a transmitting mode, the RX/TX control circuit switches the multiplexing-type filter to a low-pass filter mode and connects the multiplexer to the transmitting path, and when the radio frequency transceiver is operated in a receiving mode, the RX/TX control circuit switches the multiplexing-type filter to a complex band-pass filter mode and connects the multiplexer to the receiving path. The multiplexing filter is a first-order filter, is not suitable for multiplexing a high-order filter of a zero intermediate frequency architecture transceiver, and causes the problem of low multiplexing rate.
The existing conversion structure of the third-order filter and the fifth-order filter is lack of elimination of the frequency response peak of the filter, and the frequency response characteristic of the filter is poor.
Disclosure of Invention
In view of the foregoing, an embodiment of the present invention provides an if apparatus applied to a WLAN zero if transceiver system, so as to solve the problem of low reuse rate of the existing apparatus.
In one aspect, an embodiment of the present invention provides an intermediate frequency device for a WLAN zero intermediate frequency transceiver system, including a control component, a third order/fifth order filter, and a multiplexer;
when the zero intermediate frequency transceiver works in a transmitting mode, the control component controls the third-order/fifth-order filter to be switched to a third-order filter mode, and simultaneously controls the multiplexer to gate a transmitting channel, so that the third-order filter is connected in a transmitting link;
when the zero intermediate frequency transceiver works in a receiving mode, the control component controls the third order/fifth order filter to be switched to a fifth order filter mode, and simultaneously controls the multiplexer to gate a receiving channel, so that the fifth order filter is connected in a receiving link.
In a further development of the above method, the multiplexer comprises a first multiplexer and a second multiplexer;
one end of the first multiplexer is respectively connected with a frequency mixing component of a receiving link and a digital-to-analog conversion component of a transmitting link, and the other end of the first multiplexer is connected with the input end of the third-order/fifth-order filter; and controlling and gating the connection between the frequency mixing component of the receiving chain or the digital-to-analog conversion component of the transmitting chain and the input end of the third-order/fifth-order filter based on the control component;
one end of the second multiplexer is connected with the output end of the third-order/fifth-order filter, and the other end of the second multiplexer is respectively connected with the analog-to-digital conversion component of the receiving link and the frequency mixing component of the transmitting link; and controlling and gating the connection of the third order/fifth order filter output end and the analog-to-digital conversion component of the receiving chain or the frequency mixing component of the transmitting chain based on the control component.
Further, the device also comprises a first programmable gain amplifier, a second programmable gain amplifier and/or a third programmable gain amplifier;
wherein the first programmable gain amplifier is connected between a mixing component of the receive chain and the first multiplexer; the second programmable gain amplifier is connected between the output end of the third-order/fifth-order filter and the second multiplexer; the third programmable gain amplifier is connected between the second multiplexer and an analog-to-digital conversion component of the receive chain.
Further, the third-order/fifth-order filter comprises a first operational amplifier, a second operational amplifier, a third operational amplifier, a fourth operational amplifier and a fifth operational amplifier which are connected in sequence; first resistors (R9, R10, R15, R16, R21, R22, R27 and R28) are connected in series between the inverting output end of the operational amplifier and the non-inverting input end of the next operational amplifier and between the non-inverting output end of the operational amplifier and the inverting input end of the next operational amplifier;
the third order/fifth order filter also comprises switches K1-K12; wherein the switch K1 is connected in series between the inverting output terminal of the second operational amplifier and the non-inverting input terminal of the third operational amplifier, the switch K2 is connected in series between the non-inverting output terminal of the second operational amplifier and the inverting input terminal of the third operational amplifier, the switches K3 and K7 are connected in series between the inverting output terminal of the second operational amplifier and the inverting output terminal of the fourth operational amplifier, the switches K4 and K8 are connected in series between the non-inverting output terminal of the second operational amplifier and the non-inverting output terminal of the fourth operational amplifier, the switches K5 and K9 are connected in series between the non-inverting output terminal of the third operational amplifier and the non-inverting output terminal of the fifth operational amplifier, the switches K6 and K10 are connected in series between the inverting output terminal of the third operational amplifier and the inverting output terminal of the fifth operational amplifier, the switch K11 is connected in series between the non-inverting input terminal of the fourth, the switch K12 is connected in series between the inverting input end of the fourth operational amplifier and the inverting output end of the fifth operational amplifier;
the control component controls the switches K3, K4, K9 and K10 to be closed and the switches K1, K2, K5-K8, K11 and K12 to be opened so that the third-order/fifth-order filter is switched into a third-order filter mode; and the switches K1, K2, K5-K8, K11 and K12 are controlled to be closed, and K3, K4, K9 and K10 are controlled to be opened, so that the third-order/fifth-order filter is switched to a fifth-order filter mode.
Further, the third/fifth order filter further comprises a resistor R1 and a resistor R2, and is used for adjusting the gain of the filter;
one end of the resistor R1 is connected with the non-inverting input end of the first operational amplifier, the other end of the resistor R1 is the positive voltage input end of the third-order/fifth-order filter, one end of the resistor R2 is connected with the inverting input end of the first operational amplifier, and the other end of the resistor R2 is the negative voltage input end of the third-order/fifth-order filter.
Further, the resistance of the resistor R1 is equal to the resistance of the resistor R2.
Further, resistance-capacitance series branches are connected between the non-inverting input end and the inverting output end of the first operational amplifier, the second operational amplifier, the third operational amplifier, the fourth operational amplifier and the fifth operational amplifier, and between the inverting input end and the non-inverting output end of the first operational amplifier and between the inverting input end and the non-inverting output end of the second operational amplifier; and second resistors (R3, R4, R29 and R30) connected with the resistor-capacitor series branch in parallel are further arranged between the non-inverting input end and the inverting output end and between the inverting input end and the non-inverting output end of the first operational amplifier and the fifth operational amplifier.
Further, the resistors in each of the rc series branches are variable resistors (R5, R6, R13, R14, R17, R18, R23, R24, R31, and R32) and have equal resistance values, and the capacitors (C1 to C10) in each of the rc series branches are variable capacitors and have equal capacitance values.
Further, the third/fifth order filter further comprises a resistor R11 and a resistor R12;
one end of the resistor R11 is connected with the non-inverting input end of the second operational amplifier, and the other end of the resistor R11 is connected with one ends of the switches K5 and K9; one end of the resistor R12 is connected with the inverting input end of the second operational amplifier, and the other end is connected with one ends of the switches K6 and K10.
Further, the resistance of the resistor R11 is equal to the resistance of the resistor R12.
Compared with the prior art, the invention can realize at least one of the following beneficial effects:
1. the third order/fifth order filter provided by the invention is matched with the multiplexer for use, so that the problem that the prior art is not suitable for multiplexing the high-order filter of the transceiver with the zero intermediate frequency architecture is solved, the switching between the third order filter and the fifth order filter is realized, and the multiplexing rate of an intermediate frequency device is improved.
2. The control assembly controls the multiplexer to be connected with the sending channel or the receiving channel, the problem that a large amount of chip area is occupied by independently designing the sending link and the receiving link is solved, miniaturization of the intermediate frequency device is achieved, the chip area is saved, and cost is reduced.
3. The present application provides a first programmable gain amplifier (PGA1), a second programmable gain amplifier (PGA2), and a third programmable gain amplifier (PGA3), wherein the third/fifth order filter generally provides a limited gain, and the PGA1 and the cascaded PGA2 and PGA3 can provide a wider gain range. In addition, the gain in the filter circuit is flexibly controlled, and the large gain range and the small gain stepping are conveniently realized for receiving the intermediate frequency; for the transmit intermediate frequency, a third/fifth order filter is connected in series with a second programmable gain amplifier (PGA2), also achieving a large gain range and small gain steps.
4. The application provides a three/five-order filter circuit, adopts the negative feedback circuit that operational amplifier constitutes, has improved operational amplifier magnification's stability, has reduced the non-linear distortion of signal to the interference of noise to the signal has been restrained, simultaneously, has reduced the consumption of intermediate frequency device, has improved the reliability of intermediate frequency device.
5. The application is provided with a resistance-capacitance series branch for adjusting a third-order/fifth-order filter, the resistance-capacitance series branch forms a lossless integrator, the lossless integrator has the advantages of low power consumption, low voltage, wide gain regulation and control and the like, the existing operational amplifier is only provided with a branch formed by connecting a capacitor and a resistor in parallel, the gain bandwidth is limited, if the variable resistor is not used for adjustment, a peak can be generated at the cut-off frequency of the amplitude-frequency response of the filter, the frequency response characteristic of the filter is influenced, and the frequency performance of the filter is reduced. Meanwhile, the second resistor and the resistance-capacitance series branch are connected in parallel to form the lossy integrator, so that the situation that the integrator is saturated and loses the integration function due to direct-current bias is avoided, and the reliability of the filter is improved.
In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.
FIG. 1 is a circuit configuration diagram of a multiplexing method of a filter;
FIG. 2 is a circuit diagram of an intermediate frequency device in one embodiment;
FIG. 3 is a block diagram of a third/fifth order filter circuit in one embodiment;
reference numerals:
100-a control component; 200-third/fifth order filters; 310-a first multiplexer; 320-a second multiplexer; 410-a first programmable gain amplifier; 420-a second programmable gain amplifier; 430-third programmable gain amplifier.
Detailed Description
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate preferred embodiments of the invention and together with the description, serve to explain the principles of the invention and not to limit the scope of the invention.
An embodiment of the present invention discloses an if apparatus applied to a WLAN zero if transceiver system, as shown in fig. 2, including a control component 100, a third/fifth order filter 200 and a multiplexer; when the zero intermediate frequency transceiver works in a transmitting mode, the control component controls the third-order/fifth-order filter to be switched to a third-order filter mode, and simultaneously controls the multiplexer to gate a transmitting channel, so that the third-order filter is connected in a transmitting link; when the zero intermediate frequency transceiver works in a receiving mode, the control component controls the third order/fifth order filter to be switched to a fifth order filter mode, and simultaneously controls the multiplexer to gate a receiving channel, so that the fifth order filter is connected in a receiving link.
When the device is implemented, the control component is respectively connected with the third-order/fifth-order filter and the control end of the multiplexer, the control component realizes the switching between the third-order filter and the fifth-order filter by controlling the third-order/fifth-order filter, and the control component realizes the gating of the transmitting channel or the receiving channel by controlling the multiplexer.
The third order/fifth order filter provided by the embodiment is used in cooperation with the multiplexer, so that the problem that the prior art is not suitable for multiplexing of a high-order filter of a zero intermediate frequency architecture transceiver is solved, the switching between the third order filter and the fifth order filter is realized, and the multiplexing rate of an intermediate frequency device is improved.
Preferably, the multiplexer includes a first multiplexer 310 and a second multiplexer 320; one end of the first multiplexer is respectively connected with a frequency mixing component of a receiving link and a digital-to-analog conversion component of a transmitting link, and the other end of the first multiplexer is connected with the input end of the third-order/fifth-order filter; and controlling and gating the connection between the frequency mixing component of the receiving chain or the digital-to-analog conversion component of the transmitting chain and the input end of the third-order/fifth-order filter based on the control component; one end of the second multiplexer is connected with the output end of the third-order/fifth-order filter, and the other end of the second multiplexer is respectively connected with the analog-to-digital conversion component of the receiving link and the frequency mixing component of the transmitting link; and controlling and gating the connection of the third order/fifth order filter output end and the analog-to-digital conversion component of the receiving chain or the frequency mixing component of the transmitting chain based on the control component.
The control assembly controls the multiplexer to be connected with the sending channel or the receiving channel, the problem that a large amount of chip area is occupied by independently designing the sending link and the receiving link is solved, miniaturization of the intermediate frequency device is achieved, the chip area is saved, and cost is reduced.
Preferably, a first programmable gain amplifier 410, a second programmable gain amplifier 420 and/or a third programmable gain amplifier 430; wherein the first programmable gain amplifier is connected between a mixing component of the receive chain and the first multiplexer; the second programmable gain amplifier is connected between the output end of the third-order/fifth-order filter and the second multiplexer; the third programmable gain amplifier is connected between the second multiplexer and an analog-to-digital conversion component of the receive chain.
Specifically, when the zero intermediate frequency transceiver operates in a transmission mode, the first multiplexer 310, the third/fifth order filter 200, the second programmable gain amplifier 420 and the second multiplexer 320 in the intermediate frequency device operate simultaneously, wherein the third/fifth order filter 200 is switched to a third order filter mode, the first multiplexer and the second multiplexer are connected to a transmission channel, and the third order filter is connected to a transmission link, so that the transmission of signals is realized. When the zero intermediate frequency transceiver works in a receiving mode, the first programmable gain amplifier 410, the first multiplexer 310, the third order/fifth order filter 200, the second programmable gain amplifier 420, the second multiplexer 320 and the third programmable gain amplifier 430 in the intermediate frequency device work simultaneously, wherein the third order/fifth order filter 200 is switched to a fifth order filter mode, the first multiplexer and the second multiplexer are connected with a transmitting channel, and the third order filter is connected with a transmitting chain to realize the receiving of signals.
Compared with fig. 1, the present application provides the first programmable gain amplifier (PGA1), the second programmable gain amplifier (PGA2), and the third programmable gain amplifier (PGA3), and the third/fifth order filter generally provides a limited gain, while PGA1 and cascaded PGA2 and PGA3 can provide a larger gain range. Meanwhile, the gain in the filter circuit is flexibly controlled, and a large gain range and small gain stepping are conveniently realized for receiving the intermediate frequency; for the transmit intermediate frequency, a third/fifth order filter is connected in series with a second programmable gain amplifier (PGA2), also achieving a large gain range and small gain steps.
The gain of three programmable gain amplifiers in the intermediate frequency device is calculated by
Wherein R isaIs the input resistance of a programmable gain amplifier, RiFor adjustable resistance, the resistance R can be adjustediA corresponding gain is obtained. In the embodiment, the programmable gain amplifier and the third-order/fifth-order filter are matched with each other, and the programmable gain amplifier with a higher gain bandwidth product is obtained by adjusting the adjustable resistor of the programmable gain amplifier, so that the design difficulty of the high-gain active RC filter is reduced, the combination of coarse gain adjustment and fine gain adjustment is realized, and the flexibility of gain control of the intermediate frequency device is improved.
Preferably, as shown in the circuit structure diagram of the third/fifth order filter of fig. 3, the third/fifth order filter includes a first operational amplifier OP1, a second operational amplifier OP2, a third operational amplifier OP3, a fourth operational amplifier OP4, and a fifth operational amplifier OP5 connected in sequence; first resistors (R9, R10, R15, R16, R21, R22, R27 and R28) are connected in series between the inverting output end of the operational amplifier and the non-inverting input end of the next operational amplifier and between the non-inverting output end of the operational amplifier and the inverting input end of the next operational amplifier; the third order/fifth order filter also comprises switches K1-K12, resistors R25 and R26; wherein, the switch K1 is connected in series between the inverting output terminal of the second operational amplifier and the non-inverting input terminal of the third operational amplifier, the switch K2 is connected in series between the non-inverting output terminal of the second operational amplifier and the inverting input terminal of the third operational amplifier, the switches K3 and K7 are connected in series between the inverting output terminal of the second operational amplifier and the inverting output terminal of the fourth operational amplifier, the switches K4 and K8 are connected in series between the non-inverting output terminal of the second operational amplifier and the non-inverting output terminal of the fourth operational amplifier, the switches K5 and K9 are connected in series between the non-inverting output terminal of the third operational amplifier and the non-inverting output terminal of the fifth operational amplifier, the switches K6 and K10 are connected in series between the inverting output terminal of the third operational amplifier and the inverting output terminal of the fifth operational amplifier, the switch K11 and the resistor R25 are connected in series between the non-inverting input terminal of, the switch K12 and the resistor R26 are connected in series between the inverting input end of the fourth operational amplifier and the inverting output end of the fifth operational amplifier; the control component controls the switches K3, K4, K9 and K10 to be closed and the switches K1, K2, K5-K8, K11 and K12 to be opened so that the third-order/fifth-order filter is switched into a third-order filter mode; and the switches K1, K2, K5-K8, K11 and K12 are controlled to be closed, and K3, K4, K9 and K10 are controlled to be opened, so that the third-order/fifth-order filter is switched to a fifth-order filter mode. Compared with the prior art, the control assembly of the application can form a negative feedback amplifying circuit while realizing mode switching of a third-order filter and a fifth-order filter by controlling the corresponding switches, for example, when the filter works in the fifth-order filter mode, the fourth operational amplifier OP4, the fifth operational amplifier OP5 and the switch K11 form the negative feedback amplifying circuit, the stability of the amplification factor of the operational amplifier is improved, the nonlinear distortion of signals is reduced, and the interference of noise to the signals is inhibited. Meanwhile, based on the circuit structure of the filter, the filter of the corresponding approximation function can be realized by adopting the approximation function of the all-pole filter such as Chebyshev, Butterworth and the like.
Specifically, the first resistor includes resistors R9, R10, R15, R16, R21, R22, R27, and R28, wherein a resistor R9 is connected in series between an inverting output terminal of the first operational amplifier OP1 and an inverting input terminal of the second operational amplifier OP2, a resistor R10 is connected in series between an inverting output terminal of the first operational amplifier OP1 and an inverting input terminal of the second operational amplifier OP2, a resistor R15 and a switch K1 are connected in series between an inverting output terminal of the second operational amplifier OP1 and an inverting input terminal of the third operational amplifier OP1, a resistor R1 is connected in series between an inverting output terminal of the third operational amplifier OP1 and an inverting input terminal of the fourth operational amplifier OP1, the resistor R27 and the switch K7 are connected in series between the inverting output terminal of the fourth operational amplifier OP4 and the non-inverting input terminal of the fifth operational amplifier OP5, and the resistor R28 and the switch K8 are connected in series between the non-inverting output terminal of the fourth operational amplifier OP4 and the inverting input terminal of the fifth operational amplifier OP 5.
Compared with the prior art, the positive feedback circuit formed by the operational amplifier is not adopted in the application. In contrast, in this embodiment, if the non-inverting input terminal of the second operational amplifier OP2 is positive, the positive output terminal of the second operational amplifier OP2 is positive, and when the switch K4 is on, the switch K2 is off, and the switch K9 is on, the negative input terminal of the fifth operational amplifier OP5 is positive, the negative output terminal is positive, and the positive output terminal is negative, the positive output terminal is fed back to the positive input terminal of the second operational amplifier OP2 through the switch K9, and the feedback is negative. In the prior art, the gain of an amplifier can be improved by using a positive feedback amplifying circuit of a filter, the positive feedback amplifying circuit can amplify very fine input signals, the deep negative feedback amplifying circuit possibly causes the whole amplifier to work abnormally to cause the circuit to self-excite, and under the condition of no input signals, the self-excitation can cause the circuit to still have waveform output with certain frequency, so that the reliability of the filter is reduced; in the application, the whole circuit structure is considered, the resistance-capacitance series branch formed by the variable resistor connected with the capacitor in series is arranged, and the gain can be improved by adjusting the resistance value of the variable resistor in the resistance-capacitance series branch; therefore, a positive feedback amplifying circuit is not needed to increase the gain of the amplifier. Considering that a filter with higher amplifier gain is easily interfered by noise, the negative feedback amplifying circuit formed by the operational amplifier is arranged to improve the stability of the amplification factor of the operational amplifier, reduce the nonlinear distortion of signals and inhibit the interference of the noise to the signals, namely, the negative feedback amplifying circuit is arranged to be obtained from the whole circuit structure of the whole filter and put into a circuit due to the control of a control component on a corresponding switch, and the filter formed by the negative feedback amplifying circuit reduces the power consumption of an intermediate frequency device and improves the reliability of the intermediate frequency device.
Preferably, the third/fifth order filter further comprises a resistor R1 and a resistor R2 for adjusting the gain of the filter; one end of the resistor R1 is connected with the non-inverting input end of the first operational amplifier, the other end of the resistor R1 is the positive voltage input end of the third-order/fifth-order filter, one end of the resistor R2 is connected with the inverting input end of the first operational amplifier, and the other end of the resistor R2 is the negative voltage input end of the third-order/fifth-order filter; the resistance R1 is equal to the resistance R2.
Specifically, the third/fifth order filter has a bandwidth of
Wherein K is a proportional coefficient of resistance, is determined by all resistances in the third-order/fifth-order filter circuit structure, and can be adjusted by adjusting the capacitance C1Get the corresponding bandwidth. The formula for calculating the gain of the third order/fifth order filter is
Wherein R is1The resistance value of the input end resistor of the third-order/fifth-order filter is K' which is a resistor parameter and is obtained by the resistors (R3 and R4) of the first-stage lossy integrator, and the value of the resistor is a multiple of the resistor R3. The gain of the third-order/fifth-order filter is controlled by adjusting the resistance value of the resistor R1, and the filter is simple to operate and easy to implement.
Preferably, a resistance-capacitance series branch is connected between the non-inverting input end and the inverting output end of the first operational amplifier, the second operational amplifier, the third operational amplifier, the fourth operational amplifier and the fifth operational amplifier, and between the inverting input end and the non-inverting output end of the first operational amplifier, the resistance-capacitance series branch constitutes a lossless integrator, and the lossless integrator is implementedThe method has the advantages of low power consumption, low voltage, wider gain control and the like. The frequency response spike is calculated as
The prior operational amplifier is only provided with a branch circuit formed by connecting a capacitor and a resistor in parallel, so that the gain bandwidth product A' is limited, and if the variable resistor is not used for adjusting RzThe magnitude of (1) is larger, the peak generated at the cut-off frequency of the amplitude-frequency response of the filter is larger, the frequency response characteristic of the filter is influenced, and the frequency performance of the filter is reducedz(R5, R6, R13, R14, R17, R18, R23, R24, R31 and R32) by adjusting the resistance RzThe frequency response peak of the filter is reduced, and meanwhile, the resistance of the resistance-capacitance series branch is a variable resistance, so that the deviation caused by the process and the temperature in the actual working condition can be reduced, and the frequency response characteristic of the third-order/fifth-order filter is improved. The filter also comprises second resistors (R3, R4, R29 and R30) connected with the resistance-capacitance series branch in parallel between the non-inverting input end and the inverting output end and between the inverting input end and the non-inverting output end of the first operational amplifier and the fifth operational amplifier, and a lossy integrator is formed by the second resistors (R3, R4, R29 and R30) connected with the resistance-capacitance series branch in parallel, so that the situation that the integrator is saturated and loses the integration function due to direct-current bias is avoided, and the reliability of the filter is improved. . Preferably, the resistors in each of the rc series branches are variable resistors (R5, R6, R13, R14, R17, R18, R23, R24, R31, and R32) and have equal resistance values, and the capacitors (C1 to C10) in each of the rc series branches are variable capacitors and have equal capacitance values. The resistance values of variable resistors (R5, R6, R13, R14, R17, R18, R23, R24, R31 and R32) and a capacitor C in the circuit1The capacitance value of the filter is in reciprocal relation, and only the capacitance C needs to be adjusted for separately debugging the gain and the bandwidth of the third-order/fifth-order filter1The resistance value of the variable resistor can be obtained, and then the corresponding gain and bandwidth can be obtained. Meanwhile, the capacitance values of the capacitors C1-C10 are the same, so that the circuit is simplified, and the circuit structure of the third-order/fifth-order filter is simpler and is easy to implement. The specific capacity value is selected according to the third orderThe design requirement of the/fifth order filter is determined and reasonable.
Specifically, the resistance-capacitance series branch comprises resistors R5, R6, R13, R14, R17, R18, R23, R24, R31, R32 and capacitors C1-C10; the resistors R5, R6, R13, R14, R17, R18, R23, R24, R31 and R32 are all variable resistors and are used for adjusting the magnitude of frequency response spikes of the third-order/fifth-order filter; the capacitors C1-C10 are variable capacitors and are used for adjusting the bandwidth of the filter.
Wherein, a capacitor C1 and a resistor R5 are connected in series between the non-inverting input terminal and the inverting output terminal of the first operational amplifier, a capacitor C2 and a resistor R6 are connected in series between the inverting input terminal and the non-inverting output terminal of the first operational amplifier, a capacitor C3 and a resistor R13 are connected in series between the non-inverting input terminal and the inverting output terminal of the second operational amplifier, a capacitor C4 and a resistor R14 are connected in series between the inverting input terminal and the non-inverting output terminal of the second operational amplifier, a capacitor C5 and a resistor R17 are connected in series between the non-inverting input terminal and the inverting output terminal of the third operational amplifier, a capacitor C6 and a resistor R18 are connected in series between the inverting input terminal and the non-inverting output terminal of the third operational amplifier, a capacitor C7 and a resistor R23 are connected in series between the non-inverting input terminal and the inverting output terminal of the fourth operational amplifier, a capacitor C85, the capacitor C9 and the resistor R31 are connected in series between the non-inverting input terminal and the inverting output terminal of the fifth operational amplifier, and the capacitor C10 and the resistor R32 are connected in series between the inverting input terminal and the non-inverting output terminal of the fifth operational amplifier.
The second resistor comprises resistors R3, R4, R29 and R30, wherein the resistor R3 is connected in series between the non-inverting input end and the inverting output end of the first operational amplifier, the resistor R4 is connected in series between the inverting input end and the non-inverting output end of the first operational amplifier, the resistor R29 is connected in series between the non-inverting input end and the inverting output end of the fifth operational amplifier, and the resistor R30 is connected in series between the inverting input end and the non-inverting output end of the fifth operational amplifier.
The control of the response peak size of the third-order/fifth-order filter is realized by adjusting the resistance size in the resistance-capacitance series branch of the third-order/fifth-order filter, the requirement of the third-order/fifth-order filter on the high gain bandwidth of the operational amplifier is reduced, and the frequency response characteristic of the third-order/fifth-order filter is improved. Meanwhile, the second resistors (R3, R4, R29 and R30) and the resistor-capacitor series branch are connected in parallel to form the lossy integrator, so that the situation that the integrator is saturated and loses the integration function due to direct-current bias is avoided, and the reliability of the filter is improved.
Preferably, the third/fifth order filter further comprises a resistor R11 and a resistor R12; one end of the resistor R11 is connected with the non-inverting input end of the second operational amplifier, and the other end of the resistor R11 is connected with one ends of the switches K5 and K9; one end of the resistor R12 is connected with the inverting input end of the second operational amplifier, and the other end is connected with one ends of the switches K6 and K10. Preferably, the resistance R11 is equal to the resistance R12. Specifically, the resistor R11 and the resistor R12 are variable resistors, and different resistors can be configured according to different requirements of the third-order filter and the fifth-order filter on the resistance values of the resistors.
In summary, the if device in the present invention can respectively operate in the third-order filter mode or the fifth-order filter mode when the zero-if transceiver operates in the transmitting or receiving mode, thereby achieving the effect of multiplexing between the transmitting end and the receiving end, improving the multiplexing rate, saving the area of the if device chip, and reducing the cost.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (9)
1. An intermediate frequency device applied to a WLAN zero intermediate frequency transceiver system is characterized by comprising a control component, a third order/fifth order filter and a multiplexer;
when the zero intermediate frequency transceiver works in a transmitting mode, the control component controls the third-order/fifth-order filter to be switched to a third-order filter mode, and simultaneously controls the multiplexer to gate a transmitting channel, so that the third-order filter is connected in a transmitting link;
when the zero intermediate frequency transceiver works in a receiving mode, the control component controls the third order/fifth order filter to be switched to a fifth order filter mode, and simultaneously controls the multiplexer to gate a receiving channel, so that the fifth order filter is connected in a receiving link;
the third-order/fifth-order filter comprises a first operational amplifier, a second operational amplifier, a third operational amplifier, a fourth operational amplifier and a fifth operational amplifier which are connected in sequence; first resistors (R9, R10, R15, R16, R21, R22, R27 and R28) are connected in series between the inverting output end of the operational amplifier and the non-inverting input end of the next operational amplifier and between the non-inverting output end of the operational amplifier and the inverting input end of the next operational amplifier;
the third order/fifth order filter also comprises switches K1-K12; wherein the switch K1 is connected in series between the inverting output terminal of the second operational amplifier and the non-inverting input terminal of the third operational amplifier, the switch K2 is connected in series between the non-inverting output terminal of the second operational amplifier and the inverting input terminal of the third operational amplifier, the switches K3 and K7 are connected in series between the inverting output terminal of the second operational amplifier and the inverting output terminal of the fourth operational amplifier, the switches K4 and K8 are connected in series between the non-inverting output terminal of the second operational amplifier and the non-inverting output terminal of the fourth operational amplifier, the switches K5 and K9 are connected in series between the non-inverting output terminal of the third operational amplifier and the non-inverting output terminal of the fifth operational amplifier, the switches K6 and K10 are connected in series between the inverting output terminal of the third operational amplifier and the inverting output terminal of the fifth operational amplifier, the switch K11 is connected in series between the non-inverting input terminal of the fourth, the switch K12 is connected in series between the inverting input end of the fourth operational amplifier and the inverting output end of the fifth operational amplifier;
the control component controls the switches K3, K4, K9 and K10 to be closed and the switches K1, K2, K5-K8, K11 and K12 to be opened so that the third-order/fifth-order filter is switched into a third-order filter mode; and the switches K1, K2, K5-K8, K11 and K12 are controlled to be closed, and K3, K4, K9 and K10 are controlled to be opened, so that the third-order/fifth-order filter is switched to a fifth-order filter mode.
2. The if arrangement according to claim 1, wherein the multiplexer comprises a first multiplexer and a second multiplexer;
one end of the first multiplexer is respectively connected with a frequency mixing component of a receiving link and a digital-to-analog conversion component of a transmitting link, and the other end of the first multiplexer is connected with the input end of the third-order/fifth-order filter; and controlling and gating the connection between the frequency mixing component of the receiving chain or the digital-to-analog conversion component of the transmitting chain and the input end of the third-order/fifth-order filter based on the control component;
one end of the second multiplexer is connected with the output end of the third-order/fifth-order filter, and the other end of the second multiplexer is respectively connected with the analog-to-digital conversion component of the receiving link and the frequency mixing component of the transmitting link; and controlling and gating the connection of the third order/fifth order filter output end and the analog-to-digital conversion component of the receiving chain or the frequency mixing component of the transmitting chain based on the control component.
3. The if arrangement of claim 2, further comprising a first programmable gain amplifier, a second programmable gain amplifier and/or a third programmable gain amplifier;
wherein the first programmable gain amplifier is connected between a mixing component of the receive chain and the first multiplexer; the second programmable gain amplifier is connected between the output end of the third-order/fifth-order filter and the second multiplexer; the third programmable gain amplifier is connected between the second multiplexer and an analog-to-digital conversion component of the receive chain.
4. The if apparatus of claim 3, wherein the third/fifth order filter further comprises a resistor R1 and a resistor R2 for adjusting the gain of the filter;
one end of the resistor R1 is connected with the non-inverting input end of the first operational amplifier, the other end of the resistor R1 is the positive voltage input end of the third-order/fifth-order filter, one end of the resistor R2 is connected with the inverting input end of the first operational amplifier, and the other end of the resistor R2 is the negative voltage input end of the third-order/fifth-order filter.
5. The IF device according to claim 4, wherein the resistor R1 is equal to the resistor R2.
6. The intermediate frequency apparatus according to claim 5, wherein a resistor-capacitor series branch is connected between the non-inverting input terminal and the inverting output terminal of the first operational amplifier, the second operational amplifier, the third operational amplifier, the fourth operational amplifier and the fifth operational amplifier, and between the inverting input terminal and the non-inverting output terminal; and second resistors (R3, R4, R29 and R30) connected with the resistor-capacitor series branch in parallel are further arranged between the non-inverting input end and the inverting output end and between the inverting input end and the non-inverting output end of the first operational amplifier and the fifth operational amplifier.
7. The IF apparatus according to claim 6, wherein the resistors in each of the RC series branches are variable resistors (R5, R6, R13, R14, R17, R18, R23, R24, R31, R32) with equal resistance, and the capacitors (C1-C10) in each of the RC series branches are variable capacitors with equal capacitance.
8. The IF device according to claim 7, wherein the third/fifth order filter further comprises a resistor R11 and a resistor R12;
one end of the resistor R11 is connected with the non-inverting input end of the second operational amplifier, and the other end of the resistor R11 is connected with one ends of the switches K5 and K9; one end of the resistor R12 is connected with the inverting input end of the second operational amplifier, and the other end is connected with one ends of the switches K6 and K10.
9. The IF device according to claim 8, wherein the resistor R11 is equal to the resistor R12.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH11220355A (en) * | 1998-01-30 | 1999-08-10 | Sony Corp | Signal processing circuit |
| CN101145768A (en) * | 2006-09-13 | 2008-03-19 | 富士通媒体部品株式会社 | Acoustic wave device, resonator and filter |
| CN102104393A (en) * | 2009-12-16 | 2011-06-22 | 天津海泰超导电子有限公司 | FDD (Frequency Division Duplex) high-temperature superconducting RF (Radio Frequency) front end subsystem |
| CN107888224A (en) * | 2017-12-18 | 2018-04-06 | 南京中感微电子有限公司 | A kind of radio transceiver machine |
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| KR100734873B1 (en) * | 2005-12-12 | 2007-07-03 | 한국전자통신연구원 | Wavelength tracking apparatus and method in WDM-PON system |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11220355A (en) * | 1998-01-30 | 1999-08-10 | Sony Corp | Signal processing circuit |
| CN101145768A (en) * | 2006-09-13 | 2008-03-19 | 富士通媒体部品株式会社 | Acoustic wave device, resonator and filter |
| CN102104393A (en) * | 2009-12-16 | 2011-06-22 | 天津海泰超导电子有限公司 | FDD (Frequency Division Duplex) high-temperature superconducting RF (Radio Frequency) front end subsystem |
| CN107888224A (en) * | 2017-12-18 | 2018-04-06 | 南京中感微电子有限公司 | A kind of radio transceiver machine |
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