Filter and related receiving circuit

Abstract

The invention discloses a filter and a related receiving circuit, the filter is used for receiving an input signal to generate a filtered signal, and the filter comprises a first component, a first capacitor and a second component. The first component is coupled between the input signal and a first end point, the first capacitor is coupled between the first end point and a second end point, a first end of the second component is coupled to the second end point, a second end of the second component is used for outputting the filtered signal, and the first component and the second component are inductance components.

Description

Technical Field

[0001] The invention relates to a filter and a related receiving circuit. Background Art

[0002] In the current external digital pre-distortion (EDPD) circuit, in order to suppress the strength of the third-order harmonics in the received signal to achieve better third-order anti-intermodulation distortion (Counter 3 rd In the external pre-distortion circuit, a filter is set to filter out the third-order harmonics in the received signal. However, since the ground voltage to which the filter is connected and the actual ground voltage on the printed circuit board include the traces in the chip and the bond wires of the package, additional inductance effects will be caused. Therefore, the characteristics of the filter will be different from the expected ones, and the third-order harmonics in the received signal cannot be effectively filtered out. Summary of the invention

[0003] Therefore, one of the objectives of the present invention is to provide a filter that can effectively filter out the third-order harmonics in the received signal when the received ground voltage is affected by the above-mentioned additional inductance effect, so as to solve the problems described in the prior art.

[0004] In one embodiment of the present invention, a filter is disclosed, which is used to receive an input signal to generate a filtered signal, and the filter includes a first component, a first capacitor and a second component. The first component is coupled between the input signal and a first terminal, the first capacitor is coupled between the first terminal and a second terminal, a first terminal of the second component is coupled to the second terminal, and a second terminal of the second component is used to output the filtered signal, wherein the first component and the second component are inductor components.

[0005] In one embodiment of the present invention, a receiving circuit disposed in a chip is disclosed, which includes a filter and a mixer. The filter is used to receive an input signal to generate a filtered signal, wherein the filter is coupled to a ground voltage, and the ground voltage is connected to an external ground voltage outside the chip through a contact of the chip. The mixer is used to receive the filtered signal and use an oscillating signal to perform a mixing operation on the filtered signal to generate a mixed signal. In addition, the filter includes a first component, a first capacitor and a second component, wherein the first component is coupled between the input signal and a first terminal, the first capacitor is coupled between the first terminal and a second terminal, a first end of the second component is coupled to the second terminal, and a second end of the second component is used to output the filtered signal, wherein the first component and the second component are inductor components. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 FIG. 4 is a schematic diagram of a chip according to an embodiment of the present invention. Figure 2 FIG. 4 is a schematic diagram of a filter according to an embodiment of the present invention. Figure 3 FIG. 4 is a schematic diagram of a filter according to an embodiment of the present invention. DETAILED DESCRIPTION

[0007] Figure 1 FIG. 1 is a schematic diagram of a chip 100 according to an embodiment of the present invention, wherein the chip 100 at least includes a receiving circuit 110 and contacts P1 and P2. Figure 1 As shown, the receiving circuit 110 includes a front-end circuit 112, a filter 114, an attenuator 116, a mixer 118 and a transimpedance amplifier (TIA) 119. In this embodiment, the receiving circuit 110 can be used for an external pre-distortion (EDPD) circuit, that is, the receiving circuit 110 receives a signal from a transmitting circuit through the contact point P1, and after generating relevant signal distortion information, provides the transmitting circuit with a pre-distortion operation, but the present invention is not limited thereto.

[0008] In the receiving circuit 110, the front-end circuit 112 may include an electrostatic discharge (ESD) clamp circuit or other processing circuits, which are used to receive a signal Vin from the contact point P1 to generate an input signal Vin'. The filter 114 is a low-pass filter, which is used to filter out the high-frequency components in the input signal Vin' to generate a filtered signal Vin". In this embodiment, the input signal Vin' includes an in-band signal and a harmonic signal, such as a third-order harmonic (3rd -order harmonic), and the filter 114 is used to filter out these harmonic signals. The attenuator 116 performs an attenuation operation on the filtered signal Vin" to reduce its strength to generate an attenuated signal VA. The mixer 118 uses an oscillation signal LO to perform a mixing operation on the attenuated signal VA to reduce the frequency of the attenuated signal VA to generate a mixed signal VMIX. Then, the transimpedance amplifier 119 amplifies the mixed signal VMIX to generate an amplified signal VMIX', and transmits the amplified signal VMIX' to the back-end processing circuit for related processing.

[0009] In another embodiment of the present invention, the attenuator 116 may be removed from the receiving circuit 110 , that is, the mixer 118 may use the oscillating signal LO to perform a mixing operation on the filtered signal Vin″ to generate the mixed signal VMIX.

[0010] In this embodiment, the ground voltage GND' to which the filter 114 is connected is connected to the ground voltage GND on the external printed circuit board through the contact P2 of the chip 100, wherein the ground voltage GND is an external ground voltage of the chip 100. Since there may be a long wiring between the ground voltage GND' to which the filter 114 is connected and the contact P2 of the chip 100, and the contact P2 of the chip 100 and the contact P3 on the printed circuit board include the bonding wire of the package, these wiring and the bonding wire can be regarded as an equivalent inductor 102. This equivalent inductor 102 will cause the characteristics of the filter to be different from the expected, especially when the frequency of the in-band signal included in the input signal Vin' is 5GHz to 6GHz, and the frequency of the third-order harmonic is between 15GHz and 18GHz. For example, if the filter 114 is a conventional notch filter or a resistor-capacitor low-pass filter, it will not be able to effectively filter out the third-order harmonics in the input signal Vin′ due to the influence of the equivalent inductor 102 .

[0011] Therefore, this embodiment proposes a design of a filter 114, which can offset or balance the equivalent inductance 102 caused by the above-mentioned routing and bonding wires, so that the filter 114 can effectively filter out the third-order harmonics in the input signal Vin'. Figure 21 is a schematic diagram of a filter 114, the filter 114 includes inductors L1-L3, capacitors C1, C2 and resistors R1, R2, wherein the inductor L1 is coupled between the terminal N1 and the input signal Vin', the capacitor C1 is coupled between the terminal N1 and the terminal N2, the inductor L2 is coupled between the terminal N2 and the terminal N4, the inductor L3 is coupled between the terminal N1 and the terminal N3, the capacitor C2 is coupled between the terminal N3 and the terminal N4, the resistor R1 is coupled between the terminal N2 and the ground voltage GND', the resistor R2 is coupled between the terminal N3 and the ground voltage GND', and the terminal N4 is used to output the filtered signal Vin". Figure 2 In the filter 114 shown, the design of the inductors L1, L2, L3 and the capacitors C1, C2 can offset or balance the equivalent inductance 102 between the ground voltage GND' and the ground voltage GND at the contact point P3 on the external printed circuit board, so as to stabilize the performance of the filter 114. In addition, the resistors R1 and R2 are used for impedance matching between the input and output ends of the filter 114.

[0012] It should be noted that in the above-mentioned embodiment, the present invention implements the filter 114 with inductors L1, L2, and L3. In another embodiment of the present invention, any one of the inductors L1, L2, and L3 of the filter 114 can be replaced by other components with similar functions, such as inductive components. Inductive components include but are not limited to transmission lines. For example, the inductor L1 is replaced by a transmission line, and the inductors L2 and L3 are still inductors. For example, the inductors L1 and L2 are replaced by transmission lines, and the inductor L3 is still inductors. For example, the inductors L1, L2, and L3 are all replaced by transmission lines. It should be noted that when the above-mentioned replacement is implemented, the values ​​of the capacitors C1 and C2 may need to be adjusted accordingly, and these design changes should fall within the scope of the present invention.

[0013] The following table shows the Figure 2 The losses of the filter 114, the conventional resistor-capacitor low-pass filter and the band-stop filter at different frequencies, where the frequencies 5 GHz, 5.56 GHz and 6 GHz are in-band signals in the input signal Vin', and 15 GHz, 16.68 GHz and 18 GHz are the corresponding third-order harmonics. As shown in Table 1, the Figure 2 The filter 114 can maximize the loss difference between the in-band signal and the third-order harmonic, and thus has the best filtering effect.

[0014] Table 1

[0015] Figure 3is a schematic diagram of a filter 300 according to an embodiment of the present invention, wherein the filter 300 can be used as Figure 1 The filter 114 is shown. Figure 3 As shown, the filter 300 includes inductors L1, L2, capacitors C1, and resistors R1, R2, wherein the inductor L1 is coupled between a terminal N1 and an input signal Vin', the capacitor C1 is coupled between a terminal N1 and a terminal N2, the resistor R1 is coupled between a terminal N2 and a ground voltage GND', the resistor R2 is coupled between a terminal N3 and a ground voltage GND', a first end of the inductor L2 is connected to the terminal N2, and a second end of the inductor L2 is used to output a filtered signal Vin". Figure 3 In the filter 300 shown, the design of the inductors L1, L2 and the capacitor C1 can offset or balance the equivalent inductance 102 between the ground voltage GND' and the ground voltage GND at the contact point P3 on the external printed circuit board, so as to stabilize the performance of the filter 300. In addition, the resistors R1 and R2 are used for impedance matching between the input and output ends of the filter 300.

[0016] It should be noted that in the above-mentioned embodiment, the present invention implements the filter 300 with inductors L1 and L2. In another embodiment of the present invention, any one of the inductors L1 and L2 of the filter 300 can be replaced by other components with similar functions, such as inductor components. Inductor components include but are not limited to transmission lines. For example, the inductor L1 is replaced by a transmission line, while the inductor L2 is still an inductor. For example, both the inductors L1 and L2 are replaced by transmission lines. It should be noted that when the above-mentioned replacement is implemented, the values ​​of the capacitors C1 and C2 may need to be adjusted accordingly, and these design changes should fall within the scope of the present invention.

[0017] To briefly summarize the present invention, in the filter of the present invention, by using a special inductor configuration to complete the design of the filter, it is possible to avoid affecting its performance due to imperfections in the ground voltage. Therefore, the filter of the present invention can effectively filter out third-order harmonics to improve third-order anti-intermodulation distortion (CIM3). The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the claims of the present invention should fall within the scope of the present invention.

Explanation of symbols

Claims

1. A filter, which is used to receive an input signal to generate a filtered signal, characterized in that: The filter includes: A first component coupled between the input signal and a first terminal; a first capacitor coupled between the first terminal and a second terminal; and a second component, wherein a first terminal of the second component is coupled to the second end point, and a second terminal of the second component is used to output the filtered signal; The first component and the second component are inductive components.

2. The filter according to claim 1, characterized in that Also includes: A first resistor coupled between the second terminal and a ground voltage; as well as A second resistor is coupled between the first terminal and the ground voltage.

3. The filter according to claim 1, characterized in that Also includes: a third component coupled between the first terminal and a third terminal, wherein the third component is an inductor component; as well as A second capacitor is coupled between the third terminal and a fourth terminal, wherein the fourth terminal is coupled to the second terminal of the second component, and the fourth terminal is used to output the filtered signal.

4. The filter according to claim 3, characterized in that Also includes: A first resistor coupled between the second terminal and a ground voltage; as well as A second resistor is coupled between the third terminal and the ground voltage.

5. The filter according to claim 3, characterized in that The first component, the second component and the third component include at least one inductor.

6. The filter according to claim 3, characterized in that The first component, the second component and the third component include at least one transmission line.

7. A receiving circuit, arranged in a chip, characterized in that: The receiving circuit comprises: A filter is used to receive an input signal to generate a filtered signal, wherein the filter is coupled to a ground voltage, and the ground voltage is connected to an external ground voltage outside the chip through a contact of the chip, and the filter includes: A first component coupled between the input signal and a first terminal; a first capacitor coupled between the first terminal and a second terminal; and a second component, wherein a first terminal of the second component is coupled to the second end, and a second terminal of the second component is used to output the filtered signal, wherein the first component and the second component are inductive components; and A mixer is used for receiving the filtered signal and using an oscillating signal to perform a mixing operation on the filtered signal to generate a mixed signal.

8. The filter according to claim 7, characterized in that Also includes: A first resistor coupled between the second terminal and the ground voltage; as well as A second resistor is coupled between the first terminal and the ground voltage.

9. The filter according to claim 7, characterized in that Also includes: a third component coupled between the first terminal and a third terminal, wherein the third component is an inductor component; as well as A second capacitor is coupled between the third terminal and a fourth terminal, wherein the fourth terminal is coupled to the second terminal of the second component, and the fourth terminal is used to output the filtered signal.

10. The filter according to claim 9, characterized in that Also includes: A first resistor coupled between the second terminal and the ground voltage; as well as A second resistor is coupled between the third terminal and the ground voltage.

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