TWI666897B - Device and method for handling signal interference - Google Patents

Abstract

A transmission device for processing signal interference includes a first transmission circuit for processing a first plurality of base frequency signals to generate a first plurality of radio frequency signals; a second transmission circuit for processing a second plurality of signals The baseband signal and the plurality of input signals to generate a second plurality of radio frequency signals; a feedback circuit coupled to the second transmission circuit for processing the second plurality of radio frequency signals and a plurality of leakage signals to generate a plurality of signals Error signals; and a control circuit, coupled to the first transmission circuit, the second transmission circuit, and the feedback circuit, for generating the plurality of signals based on the first plurality of fundamental frequency signals and the plurality of error signals. Enter the signal.

Description

Device and method for processing signal interference

The present invention relates to a device and method for a communication system, and more particularly to a device and method for processing signal interference.

According to the conventional technology, when different types of signals (such as signals of different communication standards) are transmitted at the same time, the signals may interfere with each other, which not only affects the transmission of the signals, but also violates the transmission specifications. Although several conventional techniques have been proposed to reduce such signal interference, such as digital pre-distortion or more expensive filters. However, these methods have the disadvantages of poor performance or excessive cost of interference cancellation. Therefore, how to reduce the signal interference in an effective and cheap way is an urgent problem.

Therefore, the present invention provides a transmission device and a transmission method for processing signal interference to solve the above problems.

The invention discloses a transmission device for processing signal interference, including a first transmission circuit for processing a first plurality of baseband signals to generate a first plurality of radio frequency signals; a second transmission circuit for processing a first Two or more baseband signals and plural input signals to generate a second plural A radio frequency signal, wherein a first frequency of the first plurality of radio frequency signals and a second frequency of the second plurality of radio frequency signals are different; a feedback circuit coupled to the second transmission circuit for processing the first Two or more radio frequency signals and multiple leak signals to generate a plurality of error signals, wherein the plurality of leak signals are related to the first plurality of radio frequency signals; and a control circuit coupled to the first transmission circuit, the first Two transmission circuits and the feedback circuit are used to generate the plurality of input signals according to the first plurality of fundamental frequency signals and the plurality of error signals.

10‧‧‧Communication System

20‧‧‧ Transmission device

200, 210, 40‧‧‧ transmission circuit

202, 212‧‧‧amplifier

220, 50‧‧‧ feedback circuit

230, 30‧‧‧ control circuit

300‧‧‧ Digital shift frequency circuit

302‧‧‧Estimated Circuit

400, 410‧‧‧L samplers

404, 414, 504, 514‧‧‧ mixers

402, 412, 502, 512‧‧‧ low-pass filters

500, 510‧‧‧ downsampler

90‧‧‧ flow

900, 902, 904, 906, 908, 910‧‧‧ steps

TX‧‧‧ sender

RX‧‧‧Receiver

FIG. 1 is a schematic diagram of a communication system according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a transmitting device according to a first embodiment of the present invention.

FIG. 3 is a schematic diagram of a control circuit according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of a transmission circuit according to a first embodiment of the present invention.

FIG. 5 is a schematic diagram of a feedback circuit according to an embodiment of the present invention.

FIG. 6 is a comparison diagram of power spectral density according to the first embodiment of the present invention.

FIG. 7 is a comparison diagram of power spectral density according to the first embodiment of the present invention.

FIG. 8 is a comparison diagram of power spectral density according to the first embodiment of the present invention.

FIG. 9 is a flowchart of a process according to an embodiment of the present invention.

FIG. 1 is a schematic diagram of a communication system 10 according to an embodiment of the present invention. The communication system 10 may be any communication system using orthogonal frequency-division multiplexing (OFDM) technology (also known as discrete multi-tone modulation (DMT) technology). It consists of a transmitting end TX and a receiving end RX. In Figure 1, the transmitting end TX and the receiving end RX It is used to describe the structure of the communication system 10. For example, the communication system 10 may be an asymmetric digital subscriber line (ADSL) system, a power line communication (PLC) system, and an Ethernet over coax (EOC) coaxial cable. And other wired communication systems. Alternatively, the communication system 10 may be a Bluetooth (BT), a wireless local area network (WLAN), a Digital Video Broadcasting (DVB) system, or a Long Term Evolution (LTE) system. And wireless communication systems such as advanced long-term evolution (LTE-advanced, LTE-A) systems, and 5th generation (5G) systems. In addition, the transmitting end TX and the receiving end RX can be set in devices such as a mobile phone, a notebook computer, and a personal computer, and are not limited thereto.

FIG. 2 is a schematic diagram of a transmitting device 20 according to an embodiment of the present invention, which can be used in the transmitting end TX of FIG. 1 to eliminate signal interference, such as mutual interference of different types of signals. The transmitting device 20 includes a transmitting circuit 200, an amplifier 202, a transmitting circuit 210, an amplifier 212, a feedback circuit 220, and a control circuit 230. In detail, the transmission circuit 200 is used to process the baseband signal x _B [n] (such as a complex signal) to generate a radio frequency signal. . The transmission circuit 210 is used to process the baseband signal x _W [n] and the input signal y _A [n] to generate a radio frequency signal Of which the radio frequency signal Frequency w _B and RF signal The frequency w _{W is} not the same. The feedback circuit 220 is coupled to the transmission circuit 210 and is used for processing radio frequency signals. And leak signals (Such as its amplified signal by adding signals) to produce an error signal e [n], where the signal is leaking Related to RF signals . The control circuit 230 is coupled to the transmission circuit 200, the transmission circuit 210, and the feedback circuit 220, and is configured to generate an input signal y _A [n] according to a base frequency signal x _B [n] and an error signal e [n]. The amplifier 202 is coupled to the transmission circuit 200, and the amplifier 212 is coupled between the transmission circuit 210 and the feedback circuit 220. The transmitting device 20 can transmit the RF signal processed by the amplifier 202 The resulting amplified signal y _{B, PO} [n], and can be transmitted to the RF signal processed by the amplifier 212 And leak signals The amplified signal y _{W, PO} [n] obtained by adding the signals of. In this embodiment, the index n can range from 0 to N-1, where N is a positive integer. In addition, if there is an attenuation gain g between the transmission circuit 200 and the transmission circuit 210, a leakage signal can be obtained. .

According to the conventional technology, when the baseband signal x _B [n] and the baseband signal x _W [n] are transmitted at the same time, the leaked signal RF signal Cause interference, not only affect RF signals Transmission also violates transmission specifications. According to the present invention, by using the feedback circuit 220 and the control circuit 230, leakage signals can be largely eliminated. While maintaining RF signals Integrity.

FIG. 3 is a schematic diagram of a control circuit 30 according to an embodiment of the present invention, which can be used in the transmitting device 20 of FIG. 2 to implement the control circuit 230. The control circuit 30 includes a digital frequency shifting (DFS) 300 and an estimation circuit 302. In detail, the digital shift frequency circuit 300 is coupled to the transmission circuit 200 and is configured to process the base frequency signal x _B [n] according to the frequency w _B and the frequency w _W to generate a frequency shift signal. . The estimation circuit 302 is coupled to the digital frequency shift circuit 300, the transmission circuit 210, and the feedback circuit 220, and processes the frequency shift signal. And the error signal e [n] to generate the input signal y _A [n], where the error signal e [n] is related to the leak signal And RF signals .

According to FIG. 3, in an embodiment, when the transmission circuit 210 processes a frequency shift signal, When a processed signal is obtained, the frequency of the processed signal is the same as the frequency w _B. In an embodiment, the estimation circuit 302 processes the frequency shift signal according to a modified normalized least mean square (modified NLMS) filter algorithm. And error signal e [n]. In one embodiment, according to the modified normalized minimum mean square filter algorithm, the error signal e [n] is defined according to the following equation: ; And ê [n | n + 1] = e [n | n + 1] -e [n-1 | n + 1] (Eq. 1)

Where x _n is the input vector of the modified normalized minimum mean square filter algorithm, w _k is the weight vector of the modified normalized minimum mean square filter algorithm, and d [n] is the leak signal ( ).

FIG. 4 is a schematic diagram of a transmission circuit 40 according to a first embodiment of the present invention, which can be used in the transmission device 20 of FIG. 2 to implement the transmission circuit 200 or the transmission circuit 210. The transmission circuit 40 includes a liter sampler (upsampler) 400, a low-pass filter (LPF) 402, a mixer 404, a liter sampler 410, a low-pass filter 412, and A mixer 414. In detail, when the transmission circuit 40 is used to implement the transmission circuit 200, the up-samplers 400 and 410 process the baseband signal x _B [n] = x _{B, I} [n] + jx _{B, Q} [n] to generate Sampling signal x _{B, S} [n] = x _{B, S, I} [n] + jx _{B, S, Q} [n]. The low-pass filters 402 and 412 are respectively coupled to the up-samplers 400 and 410, and are used to filter the up-sampled signals x _{B, S} [n] to generate filtered signals x _{B, F} [n] = x _{B, F, I} [n] + jx _{B, F, Q} [n]. The mixers 404 and 414 are respectively coupled to the low-pass filters 402 and 412, and are used to filter the signal x _{B, F} [n] according to the frequency w _B to generate a radio frequency signal. .

Similarly, when the transmission circuit 40 is used to implement the transmission circuit 210, the up-samplers 400 and 410 process the baseband signal x _W [n] = x _{W, I} [n] + jx _{W, Q} [n] to generate samples Signal x _{W, S} [n] = x _{W, S, I} [n] + jx _{W, S, Q} [n]. The low-pass filters 402 and 412 are respectively coupled to the up-samplers 400 and 410, and are used to filter the up-sampled signals x _{W, S} [n] to generate filtered signals x _{W, F} [n] = x _{W, F, I} [n] + jx _{W, F, Q} [n]. The mixers 404 and 414 are coupled to the low-pass filters 402 and 412, respectively, and are used to filter the signal x _{W, F} [n] according to the frequency w _W to generate a radio frequency signal. .

FIG. 5 is a schematic diagram of a feedback circuit 50 according to an embodiment of the present invention, which can be used in the transmission device 20 of FIG. 2 to implement the feedback circuit 220. The feedback circuit 50 includes a decimator 500, a low-pass filter 502, a mixer 504, a down-sampler 510, a low-pass filter 512, and a mixer 514. In detail, the mixers 504 and 514 are used to mix the RF signals according to the frequency w _W And leak signals Sum the signals (or their amplified signals y _{W, PO} [n]) to produce a mixed signal x _M [n] = x _{M, I} [n] + jx _{M, Q} [n]. Low-pass filters 502 and 512 are coupled to mixers 504 and 514, respectively, and are used to filter the mixed signal x _M [n] to generate a filtered signal x _{M, F} [n] = x _{M, F, I} [n ] + jx _{M, F, Q} [n]. The down-samplers 500 and 510 are coupled to the low-pass filters 502 and 512, respectively, and are used to process the filtering signals x _{M, F} [n] to generate an error signal e [n].

In one embodiment, the baseband signal x _B [n] is a Bluetooth signal, and the baseband signal x _W [n] is a wireless local area network signal, but is not limited thereto. Those with ordinary knowledge in the art can apply the present invention to a transmitting end transmitting multiple signals at the same time to solve the problem of signal interference.

Based on the above, the following uses Bluetooth and wireless local area network as an example to illustrate an embodiment of the present invention according to the transmission device 20, in which BT and WLAN represent the Bluetooth and wireless local area network respectively to improve the clarity of the statement. .

First, the BT baseband signal of the transmission circuit 200 and the WLAN baseband signal of the transmission circuit 210 are defined as follows: x _B [n] = x _{B, I} [n] + jx _{B, Q} [n]; and x _W [n ] = x _{W, I} [n] + jx _{W, Q} [n] (Eq. 2)

Where x _{B, I} [n] and x _{B, Q} [n] are the real and imaginary signals of the BT baseband signal, and x _{W, I} [n] and x _{W, Q} [n] are WLAN respectively The real and imaginary signals of the baseband signal. Then, after the BT baseband signal and the WLAN baseband signal are respectively subjected to corresponding upsampling operations (such as upsampling and low-pass filters), the upsampling operation is performed at the corresponding radio frequency (i.e. Change), become BT radio frequency signal And WLAN RF signals , Which can be expressed as follows: ;as well as

Wherein w _B and w _W are (eg, different) RF frequencies (ie, carrier frequencies) of BT and WLAN, and θ _B and θ _W are (eg, different) phases of BT and WLAN mixers, respectively.

Due to BT radio frequency signal WLAN RF signal Causes interference, considering the attenuation gain g of the path between BT and WLAN, the BT leakage signal can be Expressed as:

In the present invention, it is assumed that the amplifier 212 has a third-order non-linear model, which can indicate that the amplified signal obtained by the processing of the amplifier 212 is as follows:

Where a ₁ and a ₃ are first-order coefficients and third-order coefficients of the amplifier 212, respectively. According to (Eq. 5), under the influence of the nonlinear model of the amplifier, the WLAN radio frequency signal And BT leak signal Addition of the interfering signals will produce intermodulation interference signals S ₁ and S ₂ .

The following describes an embodiment of a control circuit of the present invention in two parts. First, the structure and operation of the control circuit will be described. In detail, the control circuit includes a digital shift frequency circuit and an estimation circuit. For example, the estimation circuit is an adaptive filter that performs an adaptive algorithm, where the adaptive algorithm It can be a normalized minimum mean square filter algorithm, but it is not limited to this. The relevant parameters of the adaptive algorithm and the three operational signals of the estimation circuit: the desired signal, the output signal of the estimation circuit, and the error signal will be defined in the following paragraphs. Then, the performance of the estimation circuit is further improved with a modified normalized minimum mean square filter algorithm.

Considering that the radio frequency w _{B of} BT and the radio frequency w _{W of} WLAN are different, the present invention first uses a digital shift frequency circuit to process the BT base frequency signal x _B [n]. In detail, according to the RF frequencies w _B and w _w , the digital shift frequency circuit shifts the BT base frequency signal x _B [n] to the frequency (w _B -w _W ) to obtain a frequency shift signal. . So the frequency shift signal After the up-scaling operation of WLAN, the frequency of the resulting signal can be compared with the BT leakage signal. The same frequency. Defines frequency-shifted signals processed by adaptive filters The resulting signal is: y _A [n] = y _{A, I} [n] + jy _{A, Q} [n] (Eq. 6)

Then, the WLAN upsampling operation and the upsampling operation are performed on the sum signal of the signal y _A [n] and the WLAN base frequency signal x _W [n] to generate a WLAN radio frequency signal. .

According to the operation of the estimated circuit, the expected signal can be a BT leak signal . The error signal (i.e. the input signal of the amplifier 212) is related to (or can be considered as) the desired signal And WLAN RF signals Sum.

According to the above, after the input signal of the amplifier 212 passes the amplifier 212 and then passes through the feedback path, it can be provided to the iterative operation to calculate the appropriate estimated circuit parameters. Based on the design of this architecture, the circuit estimates the BT leakage signal before entering the amplifier 212 A cancellation operation is performed to reduce the interference signal output by the amplifier 212.

It should be noted that if the adaptive algorithm used in the estimation circuit is a conventionally normalized minimum mean square filter algorithm, the above design can greatly eliminate the BT leakage signal. , But it also eliminates a small part of the signal of the WLAN baseband signal x _W [n], reducing the extent of performance improvement. Therefore, the present invention uses a modified normalized minimum mean square filter algorithm to improve the attenuation of the WLAN fundamental frequency signal x _W [n].

First, the two error terms (estimated circuit error signal) of the adaptive algorithm are defined as follows:

among them Is the input vector of the adaptive algorithm, w _n = [w _n [0], w _n [1], ..., w _n [L-1]] ^T is the weight vector of the adaptive algorithm and the expected signal (I.e. BT leak signal ) .

Next, define and Is the difference term. According to the Minimum Mean Square Error (MMSE) criterion, consider the following two

To solve the above equation, define Δ w _{n + 1} = w _{n + 1} - w _n , and define the following cost function according to the Lagrange multiplier method:

Among them, λ is a Lagrange multiplier of a complex number. Next, do the cost function Partial differential of, and assuming the result is 0, you can get:

Substituting (Equation 13) into (Equation 10), a complex Lagrange multiplier λ can be derived as follows:

Next, enter Lagrange multiplier λ (Equation 13), add α as the adaptive parameter (ie, step parameter), and add a small positive value of c to avoid The algorithm abnormality caused by 0 can get the following equation:

It should be noted that although the desired signal can be regarded as a BT leak signal However, in fact, the true value of d [n] cannot be obtained directly, so that ê ^* [n | n] in (Equation 15) cannot be obtained from (Equation 7) and (Equation 8). Therefore, the present invention provides a solution to approximate ê ^* [n | n] with ê ^* [n] -ê ^* [n-1]. (Eq. 15) can be modified as follows:

As the number of iterations increases, the accuracy of the above approximation can be improved. The reason is that when the number of iterations increases, the parameters will gradually converge, so that Will get closer The calculation results will become more and more accurate.

FIG. 6 is a comparison diagram of power spectrum density (PSD) according to the first embodiment of the present invention. Figure 6 shows the power spectral density of the input signal y _A [n] with a normalized minimum mean square filter algorithm and a modified normalized minimum mean square filter algorithm, where "NLMS" means normalized The result of the minimum mean square filter algorithm, and "Modified NLMS" represents the result of the modified normalized minimum mean square filter algorithm. The input signal y _A [n] is added in the reverse direction (negative value) on the WLAN transmission path to eliminate the BT leakage signal . Therefore, the more similar the BT signal output here is to the BT leak signal, the better the result of interference cancellation. In Figure 6, the result of the normalized minimum mean square filter algorithm is -62.64dBm / Hz, and the result of the modified normalized minimum mean square filter algorithm is -62.62dBm / Hz, and the actual The BT leakage interference signal is -63.63dBm / Hz. It is worth noting the result of the intermediate frequency. If there is a signal in this area, the signal will cause interference to the WLAN signal. According to Figure 6, the result of the normalized minimum mean square filter algorithm is -88.63 dBm / Hz, and the result of the modified normalized minimum mean square filter algorithm is -113 dBm / Hz. Therefore, the modified normalized minimum mean square filter algorithm can indeed reduce the amount of interference and make the quality of the WLAN signal less affected.

FIG. 7 is a comparison diagram of power spectral density according to the first embodiment of the present invention. In Figure 7, the input signal of the amplifier 212 ( + ) Will be compared: the BT leakage signal is not eliminated, the normalized minimum mean square filter algorithm is used, and the modified normalized minimum mean square filter algorithm is used. "Without Cancellation" indicates the result without any interference cancellation, "NLMS" indicates the result of the normalized minimum mean square filter algorithm, and "Modified NLMS" indicates the result of the modified normalized minimum mean square filter algorithm . The results obtained by the above three methods are: -63.63dBm / Hz, -87.87dBm / Hz, and -90.6dBm / Hz. After comparing the above differences, a normalized minimum mean square filter algorithm and a modified normalized minimum mean square filter algorithm are obtained to eliminate interference of 24.24dB and 26.97dB, respectively.

FIG. 8 is a comparison diagram of power spectral density according to the first embodiment of the present invention. In Figure 8, the output signal (y _{W, PO} [n]) of the amplifier 212 caused by different interference cancellation methods will be compared. This result is also the actual result that will be measured finally: BT leakage signal is not eliminated, use Normalized minimum mean square filter algorithm and modified normalized minimum mean square filter algorithm. "Without Cancellation" indicates the result without using any interference cancellation, "NLMS" indicates the result of the normalized minimum mean square filter algorithm, and "Modified NLMS" indicates the result of the modified normalized minimum mean square filter algorithm, "OOB" means out-of-band, and "OOB Emission" means out-of-band transmission. The results obtained by the above three methods are: -62.04 dBm / Hz, -70.11 dBm / Hz, and -68.65 dBm / Hz. After comparing the above differences, a normalized minimum mean square filter algorithm and a modified normalized minimum mean square filter algorithm are obtained to eliminate interference of 8.07dB and 6.61dB, respectively.

FIG. 9 is a flowchart of a process 90 according to an embodiment of the present invention, which is used to describe the operation mode of the aforementioned transmitting device 20, and includes the following steps: Step 900: Start.

Step 902: Process the first plurality of base frequency signals to generate a first plurality of radio frequency signals.

Step 904: Process the second plurality of base frequency signals and the plurality of input signals to generate a second plurality of radio frequency signals, wherein a first frequency of the first plurality of radio frequency signals and a first frequency of the second plurality of radio frequency signals. The two frequencies are not the same.

Step 906: Process the second plurality of radio frequency signals and the plurality of leakage signals to generate a plurality of error signals, wherein the plurality of leakage signals are related to the first plurality of radio frequency signals.

Step 908: Generate the plurality of input signals according to the first plurality of base frequency signals and the plurality of error signals.

Step 910: End.

It should be noted that the transmission circuit 200, the amplifier 202, the transmission circuit 210, the amplifier 212, the feedback circuit 220, and the control circuit 230 may be integrated into one or more circuits according to design considerations or system requirements. In addition, the transmitting device 20 and the circuits therein may be implemented by hardware, software, firmware, electronic system, or a combination of the above devices, and is not limited thereto.

In summary, the present invention provides a device and a method thereof. By using the feedback circuit and the control circuit, interference between signals generated when different types of signals are transmitted at the same time can be reduced. Compared with the conventional technology, the present invention not only has better performance, but also has lower cost. The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in accordance with the scope of patent application of the present invention shall fall within the scope of the present invention.

Claims (10)

A transmission device for processing signal interference includes: a first transmission circuit for processing a first plurality of baseband signals to generate a first plurality of radio frequency signals; a second transmission circuit for processing a second The plurality of base frequency signals and the plurality of input signals to generate a second plurality of radio frequency signals, wherein a first frequency of the first plurality of radio frequency signals and a second frequency of the second plurality of radio frequency signals are different; A feedback circuit is coupled to the second transmission circuit and is used to process the second plurality of radio frequency signals and the plurality of leakage signals to generate a plurality of error signals, wherein the plurality of leakage signals are related to the first plurality of radio frequency signals. And a control circuit coupled to the first transmission circuit, the second transmission circuit, and the feedback circuit to generate the plurality of input signals according to the first plurality of base frequency signals and the plurality of error signals. The transmission device according to claim 1, wherein the control circuit includes a digital shift frequency circuit coupled to the first transmission circuit for processing the first complex number according to the first frequency and the second frequency. Base frequency signals to generate a plurality of frequency shifted signals; and an estimation circuit coupled to the number shifted frequency circuit, the second transmission circuit and the feedback circuit for processing the plurality of frequency shifted signals and the complex number Error signals to generate the plurality of input signals, wherein the plurality of error signals are related to the plurality of leakage signals and the second plurality of radio frequency signals. The transmission device according to claim 2, wherein when the second transmission circuit processes the plurality of frequency-shifted signals to obtain the plurality of processed signals, a third frequency of the plurality of processed signals is the same as the first frequency . The transmission device according to claim 2, wherein the estimation circuit processes the plurality of frequency shift signals and the complex number according to a modified normalized least mean square (modified NLMS) filter algorithm. Error signals. The transmission device according to claim 4, wherein according to the modified normalized minimum mean square filter algorithm, the plurality of error signals are defined according to the following equation: ; And ê [n | n + 1] = e [n | n + 1] -e [n-1 | n + 1]; where x _{n is} the value of the modified normalized minimum mean square filter algorithm An input vector, w _k is a weight vector of the modified normalized minimum mean square filter algorithm, and d [n] is the plurality of leakage signals. The transmission device according to claim 1, wherein the first transmission circuit includes: a first plurality of up-samplers for processing the first plurality of base-frequency signals to generate a first plurality of up-sampled signals; A plurality of low-pass filters, coupled to the first plurality of up-samplers, for filtering the first plurality of up-sampled signals to generate a first plurality of filtered signals; and a first plurality of mixers, The first plurality of low-pass filters are coupled to mix the first plurality of filtering signals according to the first frequency to generate the first plurality of radio frequency signals. The transmission device according to claim 1, wherein the second transmission circuit includes: a second plurality of up-samplers for processing the second plurality of base-frequency signals to generate a second plurality of up-sampled signals; Two or more low-pass filters, coupled to the second plurality of up-samplers, for filtering the second plurality of up-sampled signals to generate a second plurality of filtered signals; and a second plurality of mixers, The second plurality of low-pass filters are coupled to mix the second plurality of filtering signals according to the second frequency to generate the second plurality of radio frequency signals. The transmission device according to claim 1, wherein the feedback circuit is coupled to the second transmission circuit through an amplifier. The transmission device according to claim 1, wherein the feedback circuit includes: a third plurality of mixers for mixing the second plurality of radio frequency signals and the plurality of leakage signals according to the second frequency. To generate a plurality of mixing signals; a third plurality of low-pass filters, coupled to the third plurality of mixers, for filtering the plurality of mixing signals to generate a plurality of filtering signals; and a plurality of filtering signals; and The down-sampler is coupled to the third plurality of low-pass filters and is used to process the plurality of filtering signals to generate the plurality of error signals. The transmitting device according to claim 1, wherein the first plurality of fundamental frequency signals are Bluetooth signals, and the second plurality of fundamental frequency signals are wireless local area network (WLAN) signals .