Multifunctional multimode filter

Abstract

The invention provides a multifunctional multimode filter which comprises a filter which at least comprises a first-stage filtering module and a second-stage filtering module, the first-stage filtering module and the second-stage filtering module are both active filtering modules, and the order of the filter is at least two; the direct current offset compensation module is connected with the analog I / Q signal access end of the filter so as to carry out direct current offset compensation; the orthogonal switching module is connected with the direct current offset compensation module so as to carry out orthogonal switching on the analog I / Q signal after the direct current offset compensation; the notch module is arranged between the first-stage filtering module and the second-stage filtering module, is connected with the first-stage filtering module and the second-stage filtering module, and is used for adjusting the bandwidth of the filter; and the operational amplifier bias adjusting module is connected with the first-stage filtering module and the second-stage filtering module and is used for adjusting voltage bias for operational amplifiers of the first-stage filtering module and the second-stage filtering module under different bandwidths.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of multimode filtering, and in particular to a multifunctional multimode filter. Background Art

[0002] In the field of RF communications, traditional RF receivers are typically either zero-IF or low-IF receivers, depending on the frequency difference between the receiver's local oscillator signal and the RF signal. Zero-IF receivers typically use real filters for filtering, while low-IF receivers typically use complex filters. Current filters are generally incompatible with both types of receivers because the signal bandwidths of different receivers vary widely, making it difficult for the filter bandwidth to adapt to varying signal bandwidths and filtering requirements. Furthermore, existing filters suffer from DC offset, poor suppression of specific frequencies, offsets in the positions of orthogonal frequencies, and non-configurable filter parameters, resulting in a single filter function.

[0003] In addition, due to differences in the chip's operating voltage, process angle, and temperature (PVT), the on-chip resistors and capacitors have certain deviations from the designed values, which causes the actual filter bandwidth to change. Summary of the Invention

[0004] In order to solve the above technical problems, an embodiment of the present invention provides a multifunctional multimode filter, comprising: A filter comprising at least a first-stage filter module and a second-stage filter module, wherein the first-stage filter module and the second-stage filter module are both active filter modules, and the order of the filter is at least two; A DC offset compensation module is connected to the analog I / Q signal access terminal of the filter to perform DC offset compensation; An orthogonal switching module, connected to the DC offset compensation module, to perform orthogonal switching on the analog I / Q signals after DC offset compensation; a notch module, disposed between the first-stage filtering module and the second-stage filtering module, and connected to the first-stage filtering module and the second-stage filtering module, for adjusting the bandwidth of the filter; The operational amplifier bias adjustment module is connected to the first-stage filtering module and the second-stage filtering module, and is used to adjust the voltage bias of the operational amplifiers of the first-stage filtering module and the second-stage filtering module under different bandwidths.

[0005] In one embodiment, the DC offset compensation module includes a first group of current mirrors and a second group of current mirrors. The first group of current mirrors and the second group of current mirrors each include multiple current mirrors. The multiple current mirrors are of the same or different types. The first group of current mirrors is used to amplify the input signal of the filter, and the second group of current mirrors is used to fine-tune the amplified input signal.

[0006] In one embodiment, the first set of current mirrors includes a P-type current mirror and / or an N-type current mirror, and the first-stage filter module and the second-stage filter module have different amplification factors of the input signal.

[0007] In one embodiment, the orthogonal switching module includes a first switching circuit and a second switching circuit, the first switching circuit is correspondingly connected to the input ends of the first filter unit and the second filter unit in the filter, and the first switching circuit is correspondingly connected to the output ends of the first filter unit and the second filter unit in the filter. When the enable states of different switches in the first switching circuit and the second switching circuit are different, the orthogonal switching module will adaptively send the obtained analog I / Q signals to different filter units.

[0008] In one embodiment, the filter includes a first filter unit and a second filter unit, both of which include a first-stage filtering module and a second-stage filtering module. The first filter unit corresponds to the I path of the analog I / Q signal and is used to filter the I path differential signal. The second filter unit corresponds to the Q path of the analog I / Q signal and is used to filter the Q path differential signal.

[0009] In one embodiment, the DC offset compensation module, the orthogonal switching module, the notch module, and the operational amplifier bias adjustment module are each provided in pairs, and are respectively provided in the first filter unit and the second filter unit; The two notch modules are respectively located between the first-stage filter module and the second-stage filter module in the first filter unit, and between the first-stage filter module and the second-stage filter module in the second filter unit. The notch modules are formed by two groups of resistor and capacitor circuits connected in series.

[0010] In one embodiment, the notch module includes a first circuit connected to the positive pole of the output end of the first-stage filtering module and the positive pole of the input end of the second-stage filtering module, and a second circuit connected to the negative pole of the output end of the first-stage filtering module and the negative pole of the input end of the second-stage filtering module. The first circuit and the second circuit both include a resistance circuit and a first capacitor in parallel, a second capacitor and a second resistor connected in series with the resistance circuit and the first capacitor. The first circuit and the second circuit are connected in series with each other. The resistor located between the first circuit and the positive pole of the input end of the second-stage filtering module in the filter forms the first adjustable resistor of the notch module, and the resistor located between the second circuit and the negative pole of the input end of the second-stage filtering module in the filter forms the second adjustable resistor of the notch module.

[0011] In one embodiment, the multifunctional multimode filter further comprises: The orthogonal offset module is used to cross-merge at least four analog I / Q signals of the filter when the filter is switched to the complex filter mode to achieve complex filtering.

[0012] In one embodiment, the orthogonal offset module has a switch array, and multiple switch pairs in the switch array are respectively connected to the positive or negative poles of the input and output ends of the first filter unit and the second filter unit. Multiple different resistance circuits are connected between each of the switch pairs. The two switches in the switch pair adjust the orthogonal frequency offset by turning on different resistance circuits to achieve filtering of different intermediate frequency signals.

[0013] In one embodiment, the system further includes an automatic bandwidth calibration module, the automatic bandwidth calibration module including a charging module formed by a first-stage filtering module, a discharging module connected to the charging module, and an RC calibration logic module connected to the discharging module, the RC calibration logic module including a comparator, a latch, and a data analyzer connected in sequence, the data analyzer being connected to a capacitor in the charging module; When the filter starts calibration, the charging module charges, and then the analog I-channel or Q-channel signal obtained by the charging module is coupled to the data analyzer through the discharge module to obtain the capacitance size analysis result in the charging module. The capacitance size analysis result represents whether the current value of the capacitance is too large or too small. The data analyzer generates a corresponding adjustment value based on the capacitance size analysis result, and inputs the adjustment value into the capacitance of the charging module to adjust the value of the capacitance.

[0014] Based on the disclosure of the above embodiments, it can be known that the beneficial effects of the embodiments of the present invention include enriching the functions of the filter, so that the filter can become both a real filter and a complex filter, and the parameters are configurable. In addition, due to the addition of various functional modules, the bandwidth of the filter is configurable and can be automatically calibrated to better adapt to different signal bandwidths and filtering requirements. It can also improve the DC offset, specified frequency suppression, orthogonal frequency position and other effects of the filter, thereby significantly improving the performance of the filter.

[0015] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. The purposes and other advantages of the present application can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0016] The technical solution of the present application is further described in detail below through the accompanying drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 Schematic diagram of the structure of the filter in the existing solution.

[0019] Figure 2 Schematic diagram of the structure of a multifunctional multimode filter in an embodiment of the present invention.

[0020] Figure 3 Schematic diagram of the structure of the DC offset compensation module in an embodiment of the present invention.

[0021] Figure 4 Schematic diagram of the structure of the orthogonal switching module in an embodiment of the present invention.

[0022] Figure 5 Schematic diagram of the structure of the trap module in an embodiment of the present invention.

[0023] Figure 6 Schematic diagram of the structure of the operational amplifier bias adjustment module in an embodiment of the present invention.

[0024] Figure 7 Schematic diagram of the structure of the orthogonal offset module in an embodiment of the present invention.

[0025] Figure 8 Schematic diagram of the structure of the automatic bandwidth calibration module in an embodiment of the present invention.

[0026] Reference numerals: 1-Filter; 2-DC offset compensation module; 3-Orthogonal switching module; 4-Notch module; 5-Op amp bias adjustment module; 6-First filter unit; 7-Second filter unit; 8-Orthogonal offset module; 9-Automatic bandwidth calibration module. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings, but are not intended to limit the present invention.

[0028] It should be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the following description should not be considered as limiting, but merely as an example of an embodiment. Other modifications within the scope of the present disclosure will occur to those skilled in the art.

[0029] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the general description of the present disclosure given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

[0030] These and other characteristics of the invention will become apparent from the following description of a preferred form of embodiment given as a non-limiting example with reference to the accompanying drawings.

[0031] It should also be understood that although the invention has been described with reference to certain specific examples, those skilled in the art will be able to realize many other equivalent forms of the invention that have the characteristics recited in the claims and are therefore within the scope of protection defined thereby.

[0032] The above and other aspects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0033] Specific embodiments of the present disclosure will be described hereinafter with reference to the accompanying drawings; however, it should be understood that the disclosed embodiments are merely examples of the present disclosure, which may be implemented in a variety of ways. Well-known and / or repetitive functions and structures are not described in detail to avoid obscuring the present disclosure with unnecessary or redundant detail. Therefore, the specific structural and functional details disclosed herein are not intended to be limiting, but rather serve merely as a basis and representative basis for the claims to teach those skilled in the art to variously employ the present disclosure with substantially any suitable detailed structure.

[0034] This description may use the phrases "in one embodiment," "in another embodiment," "in a further embodiment," or "in other embodiments," each of which may refer to one or more of the same or different embodiments according to the present disclosure.

[0035] The structure of the traditional real active filter is as follows Figure 1 As shown, in this embodiment, a second-order low-pass filter is used as an example for description. Figure 1 As shown, resistors R1 / R2, capacitor C1, and op amp OP1 form the first-stage active filter module, while resistor R3, capacitor C2, and op amp OP2 form the second-stage active filter module. R4 provides negative feedback between the first and second-stage filter modules. Even-order filters use the second-order filter module as the basic unit to form higher-order even-order filters. Odd-order filters use the first-order active filter module formed by R1 / R2 and C1 / OP1 and the second-order filter module as basic units to form higher-order odd-order filters.

[0036] like Figure 2 As shown, an embodiment of the present invention provides a multifunctional multimode filter, comprising: Filter 1, comprising at least a first-stage filter module and a second-stage filter module, wherein the first-stage filter module and the second-stage filter module are both active filter modules, and the order of the filter 1 is at least two; A DC offset compensation module 2 is connected to the analog I / Q signal (i.e., analog I or Q signal, the same below) access terminal of the filter 1 to perform DC offset compensation; An orthogonal switching module 3 is connected to the DC offset compensation module 2 to perform orthogonal switching on the analog I / Q signals after DC offset compensation; The notch module 4 is provided between the first-stage filtering module and the second-stage filtering module and is connected to the first-stage filtering module and the second-stage filtering module to adjust the bandwidth of the filter 1; The operational amplifier bias adjustment module 5 is connected to the first-stage filtering module and the second-stage filtering module, and is used to adjust the voltage bias of the operational amplifiers of the first-stage filtering module and the second-stage filtering module under different bandwidths.

[0037] For example, the filter 1 in this embodiment is at least a second-order filter, including a first filter unit 6 and a second filter unit 7. The first filter unit and the second filter unit each include a first-stage filter module and a second-stage filter module. The first-stage filter module and the second-stage filter module are connected in series, that is, the output end of the first-stage filter module is connected to the input end of the second-stage filter module. The first filter unit corresponds to the I path of the analog I / Q signal and is used to filter the I path differential signal. The second filter unit corresponds to the Q path of the analog I / Q signal, that is, the differential signal of the analog I / Q signal, and is used to filter the Q path differential signal.

[0038] Further, continue to combine Figure 2 As shown, resistors R1 / R2, capacitor C1, and op amp OP1 constitute a first-stage filtering module (active), resistor R3, capacitor C2, and op amp OP2 constitute a second-stage filtering module (active), and R4 forms a negative feedback between the first-stage filtering module and the second-stage filtering module. Figure 2 The filter shown in FIG is a second-order filter, comprising a first filter unit located at the top and a second filter unit located at the bottom. The first filter unit receives an I-channel analog signal, and the second filter unit receives a Q-channel analog signal. Figure 2 After the four orthogonal differential signals VIN_IP / VIN_IN and VIN_QP / VIN_QN input pass through the above-mentioned (active) filters, four orthogonal differential output signals are generated, namely VOUT_IP / VOUT_IN for the I channel and VOUT_QP / VOUT_QN for the Q channel.

[0039] There are two of each of the DC offset compensation module 2 , the orthogonal switching module 3 , the notch module and the operational amplifier bias adjustment module 5 , which are respectively arranged in the first filter unit 6 and the second filter unit 7 .

[0040] The above content is only the structure of the filter 1 in one embodiment. In actual application, the order of the filter 1 can be increased, and the specific order is uncertain. The filter 1 can be a high-order odd-number filter 1 or a high-order even-number filter 1.

[0041] The solution of this embodiment enriches the functions of the original filter, enabling filter 1 to function as both a real filter and a complex filter, thus meeting the different filtering requirements of different scenarios. Furthermore, by setting the parameters of filter 1 to be configurable and adding various functional modules, the bandwidth of filter 1 is configurable and automatically calibrated to better adapt to different signal bandwidths and filtering requirements. Furthermore, the DC offset, specified frequency suppression, and orthogonal frequency position of filter 1 can be improved, significantly enhancing the performance of filter 1.

[0042] Further, such as Figure 3 As shown, the DC offset compensation module 2 in this embodiment includes a first set of current mirrors and a second set of current mirrors. The first and second sets of current mirrors each include multiple current mirrors, which may be of the same or different types. The first set of current mirrors is used to amplify the input signal of the filter 1, and the second set of current mirrors is used to fine-tune the amplified input signal. The first set of current mirrors includes a P-type current mirror and / or an N-type current mirror, and the first-stage filter module and the second-stage filter module have different input signal amplification factors.

[0043] For example, the reference current I_REF passes through Figure 3 After the first-stage N-type current mirror and the second-stage P-type current mirror, they are amplified a times and b times respectively, and then processed by the third-stage N-type current mirror and the fourth-stage P-type current mirror and output to the differential input ports DP and DN of the op amp. The third-stage N-type current mirror is a single-time amplification, and the current flowing out through the fourth-stage P-type current mirror is the differential current that compensates for DC, which are DP <n:0>and DN <n:0>The DC offset compensation module 2 can compensate the DC offset in equal and opposite directions according to the measured DC offset. Since the first and second stage current mirrors have certain magnifications, i.e. a, b, the compensation current DP <n:0>and DN <n:0>The compensation range and accuracy will be controlled by the magnification of the previous two current mirrors. The larger the magnification a and b, the larger the compensation range, the larger the step size, and the lower the accuracy; the smaller the magnification a and b, the smaller the compensation range, the smaller the step size, and the higher the accuracy; after selecting a fixed magnification, the compensation current DP <n:0>and DN <n:0>The specific selection process can be, but is not limited to, efficiently completed through a scanning algorithm.

[0044] Furthermore, the orthogonal switching module 3 includes a first switching circuit and a second switching circuit, the first switching circuit is correspondingly connected to the input ends of the first filter unit and the second filter unit in the filter 1, and the first switching circuit is correspondingly connected to the output ends of the first filter unit and the second filter unit in the filter 1. When the enable states of different switches in the switching circuit are different, the orthogonal switching module 3 will adaptively send the obtained analog I / Q signals to different filter units.

[0045] For example, Figure 4 As shown, Figure 2 Taking module 102 in FIG1 as an example, when ENA = 1 / ENB = 0, the input differential signals VIN_IP1 / VIN_IN1 are respectively fed into the op amps A1+ / A1- of channel I; when ENA = 0 / ENB = 1, the input differential signals VIN_IP1 / VIN_IN1 are respectively fed into the op amps B1+ / B1- of channel Q. The same applies to module 202 (quadrature switching module 3) of channel Q. This completes the switching of the quadrature signals between channels I and Q. For complex filter 1, incorrect selection of channels I and Q may prevent the receiver from receiving appropriate signals at specific frequencies, leading to chip reception anomalies. However, this embodiment avoids such errors by adding the quadrature switching module 3 (102 / 202). This ensures that filter 1, whether in real or complex filtering mode, correctly selects the I and Q signals for different filter units, ensuring that the receiver receives appropriate signals at characteristic frequencies.

[0046] Furthermore, in this embodiment, the two notch modules 4 are respectively located between the first-stage filter module and the second-stage filter module in the first filter unit 6, and between the first-stage filter module and the second-stage filter module in the second filter unit 7, and the notch module 4 is formed by two groups of resistor and capacitor circuits connected in series.

[0047] Specifically, the notch module 4 includes a first circuit connected to the positive pole of the output end of the first-stage filter module and the positive pole of the input end of the second-stage filter module, and a second circuit connected to the negative pole of the output end of the first-stage filter module and the negative pole of the input end of the second-stage filter module. The first circuit and the second circuit both include a resistance circuit and a first capacitor in parallel, a second capacitor and a second resistor connected in series with the resistance circuit and the first capacitor. The first circuit and the second circuit are connected in series with each other. The resistor located between the first circuit and the positive pole of the input end of the second-stage filter module in the filter 1 forms the first adjustable resistor of the notch module 4, and the resistor located between the second circuit and the negative pole of the input end of the second-stage filter module in the filter 1 forms the second adjustable resistor of the notch module 4.

[0048] For example, combined with Figure 5 As shown in the figure, the resistor R31 (resistance circuit) and the capacitor C31 (first capacitor) are connected in parallel, and then the network connected in series with the capacitor C32 (second capacitor) and the resistor R31 (second resistor) is connected in series to divide the voltage. The result of the series voltage division is connected in series with R33 (first adjustable resistor / second adjustable resistor). Figure 5 The structure shown is a notch network composed of R31 / R32 / C31 / C32. The notch frequency can be adjusted by adjusting the size of C31 and C32. R33 is an independent adjustable resistor, which has the same function as R3 in the traditional filter 1. Figure 2 Together with C2 in the second-stage filter module, the bandwidth of filter 1 can be adjusted. Furthermore, by selecting appropriately sized resistors R31 and R32, and capacitors C31 and C32, different notch frequencies and amplitude-frequency response curves can be obtained. Based on these different frequency response curves, filter 1 can have different bandwidths and notch frequencies, enhancing its application flexibility.

[0049] Further, such as Figure 6 As shown, the operational amplifier bias adjustment module 5 (ie Figure 2 When using 104 / 204 in the figure, the input reference current is amplified by c and d times, respectively, by the N-type and P-type current mirrors in the module. This provides the appropriate current bias for the op amp in filter 1. Adjusting c and d independently adjusts the current bias. Adjusting resistors Rb1 and Rb2 in the figure adjusts the op amp's voltage bias. The op amp in the filter module can be configured with different voltage and current biases for different bandwidths, ensuring the flexibility of filter 1 for diverse scenarios.

[0050] In another embodiment, the multifunctional multimode filter further comprises: The orthogonal offset module 8 is used to cross-merge at least four analog I / Q signals of the filter 1 when the filter 1 is switched to the complex filter mode, so as to realize complex filtering.

[0051] The orthogonal offset module 8 in this embodiment is mainly used when the filter 1 is in the complex filtering mode to ensure that the differential signal entering the filtering stage is correct, so that the subsequent filter 1 can convert the obtained real signal into a complex signal output. That is, the orthogonal offset module 8 in this embodiment performs orthogonal offset correction when the signal is in the analog stage to ensure that the signal to be filtered is correct.

[0052] Furthermore, the orthogonal offset module 8 in this embodiment has a switch array, and the multiple switch pairs in the switch array are respectively connected to the positive or negative poles of the input and output ends of the first filter unit 6 and the second filter unit 7. Multiple different resistance circuits are connected between each of the switch pairs. The two switches in the switch pair adjust the orthogonal frequency offset by turning on different resistance circuits to achieve filtering of different intermediate frequency signals.

[0053] For example, Figure 7 As shown, the output of the first-stage filtering module (such as Figure 7 and Figure 2 The A2+ / A2- and B2+ / B2-) shown in the figure are respectively sent to the inputs (B1- / B1+ and A1- / A1+) of the first-stage filter module through the switch array, and the outputs (A4+ / A4- and B4+ / B4-) of the second-stage filter module are respectively sent to the inputs (B3- / B3+ and A3- / A3+) of the second-stage filter module through the switch array, thereby cross-merging the four signals of the I / Q input and output to complete a 90-degree phase shift of the real signal, converting the real signal into a complex signal for output, and achieving the purpose of complex filtering.

[0054] The second function of the quadrature offset module 8 in this embodiment is to control the size of the I / Q quadrature offset frequency in the complex filter 1 as needed. The specific implementation method is to use a resistor and switch array to achieve this. The internal structure of each switch pair is as follows: Figure 7 As shown in the enlarged partial diagram (using the switch pair between A3+ and B4- as an example), the switches in the switch pair select different resistors, such as R51, R52, and R53 (three resistors are used as an example; more resistors can be set, the specific number varies), to achieve different adjustments to the quadrature offset. For example, the smaller the selected resistor, the greater the quadrature frequency offset; conversely, the larger the selected resistor, the smaller the quadrature frequency offset. This allows filter 1 to select the appropriate intermediate frequency signal for filtering, ensuring maximum flexibility for complex filter 1.

[0055] In another embodiment, the multifunctional multimode filter 1 also includes an automatic bandwidth calibration module 9, which includes a charging module formed by a first-stage filtering module, a discharge module connected to the charging module, and an RC calibration logic module connected to the discharge module. The RC calibration logic module includes a comparator, a latch and a data analyzer connected in sequence, and the data analyzer is connected to the capacitor in the charging module.

[0056] like Figure 8 As shown, the automatic bandwidth calibration module 9 includes three parts: the first part is a charging module, which is composed of a charging power supply, a charging switch and a capacitor C1, that is, the first-stage filtering module in this embodiment; the second part is a discharging module, which is composed of capacitors C6 / C7 and resistors R6 and R7; the third part is an RC calibration logic module, that is, a data analyzer, which is composed of a comparator, a latch and a successive approximation logic module (data analyzer).

[0057] When the filter 1 starts calibration, the charging module charges, and then the analog I-channel signal or Q-channel signal obtained by the charging module is coupled to the data analyzer through the discharge module to obtain the capacitance size analysis result in the charging module. The capacitance size analysis result represents whether the current value of the capacitance is too large or too small. The data analyzer generates a corresponding adjustment value based on the capacitance size analysis result, and inputs the adjustment value into the capacitance of the charging module to adjust the value of the capacitance.

[0058] For example, continue to combine Figure 8 As shown in the figure, when EN_CAL=0 (calibration enable pin), all other switches are also disconnected, which does not affect the normal operation of the filter 1 circuit; when EN_CAL=1, it enters the calibration mode, and its calibration process is as follows: (1) First, turn on the op amp and initialize the calibration control output D<7:0> of the capacitor C1 array to 00000000 (in this embodiment, the preset quotation mark length is 8 bits, so the preset calibration bit length is 8 bits. Of course, the calibration length can also be adjusted according to actual needs, that is, the signal length is adjusted); (2) Set ENA to 1 to allow the current source to start charging the capacitor C1. After half a cycle T / 2, set ENA to 0 to stop charging; (3) Capacitor C6 is synchronized The differential output of the op amp is coupled to the input of the comparator, and after comparison, it is amplified to 1 or 0; (4) The latch saves the output of the comparator for one cycle and sends it to the successive approximation logic module. If the comparator result is 0, it indicates that the capacitor C1 is too small, and the successive approximation logic module outputs 1 at the highest bit; if the comparator result is 1, it indicates that the capacitor C1 is too large, and the successive approximation logic module outputs 0 at the highest bit; (5) After 7 / 8 cycles 7T / 8, ENB is set to 1, entering the discharge mode, and resetting the comparator input signal; after 1 cycle T, ENB is set to 0, the reset is completed, and the next round of charge and discharge mode test is ready to be entered to achieve successive approximation until the successive approximation logic module outputs D <7> to D <0> All comparison results, that is, each bit of the signal is calibrated. Taking 8 bits as an example, 8 calibrations are required; (6) At this time, the RC automatic calibration is completed, the calibration control output D<7:0> is kept unchanged, EN_CAL is set to 0, and all other switches are also disconnected, entering the normal working mode.

[0059] From the above calibration process, it can be seen that the RC automatic calibration module proposed in this embodiment has the following features: (a) The calibration process is simple. After the calibration circuit is started, all calibration processes can be completed automatically without manual intervention; (b) Since the reusing charging capacitor C1 directly reuses the capacitor C1 in the circuit, the chip area is also saved to a certain extent; (c) Most importantly, since the op amp is in a normal power-on state during the charging process, the parasitic capacitance of the op amp input and output will not affect the calibration result, making the calibration effect inaccurate.

[0060] In addition, in another embodiment, other parameters in the filter 1 can also be set to a configurable scheme, such as gain (Gain), quality factor (Q value) and group delay (GD), which can be obtained by adjusting the ratio of resistors R1 / R2 / R3 / R4.

[0061] In another embodiment, another embodiment of the present invention further provides an electronic device, comprising the multifunctional multi-mode filter as described in any one of the above.

[0062] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of protection of the present application is limited to these examples. In line with the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present application as described above, which are not provided in detail for the sake of simplicity.

Claims

1. A multifunctional multimode filter, characterized in that: include: A filter comprising at least a first-stage filter module and a second-stage filter module, wherein the first-stage filter module and the second-stage filter module are both active filter modules, and the order of the filter is at least two; A DC offset compensation module is connected to the analog I / Q signal access terminal of the filter to perform DC offset compensation; An orthogonal switching module, connected to the DC offset compensation module, to perform orthogonal switching on the analog I / Q signals after DC offset compensation; a notch module, disposed between the first-stage filtering module and the second-stage filtering module, and connected to the first-stage filtering module and the second-stage filtering module, for adjusting the bandwidth of the filter; The operational amplifier bias adjustment module is connected to the first-stage filtering module and the second-stage filtering module, and is used to adjust the voltage bias of the operational amplifiers of the first-stage filtering module and the second-stage filtering module under different bandwidths.

2. The multifunctional multimode filter according to claim 1, characterized in that: The DC offset compensation module includes a first group of current mirrors and a second group of current mirrors. The first group of current mirrors and the second group of current mirrors each include multiple current mirrors. The multiple current mirrors are of the same or different types. The first group of current mirrors is used to amplify the input signal of the filter, and the second group of current mirrors is used to fine-tune the amplified input signal.

3. The multifunctional multimode filter according to claim 2, characterized in that: The first group of current mirrors includes a P-type current mirror and / or an N-type current mirror. The first-stage filtering module and the second-stage filtering module have different amplification factors of the input signal.

4. The multifunctional multimode filter according to claim 1, characterized in that: The orthogonal switching module includes a first switching circuit and a second switching circuit. The first switching circuit is correspondingly connected to the input ends of the first filter unit and the second filter unit in the filter, and the first switching circuit is correspondingly connected to the output ends of the first filter unit and the second filter unit in the filter. When the enable states of different switches in the first switching circuit and the second switching circuit are different, the orthogonal switching module will adaptively send the obtained analog I / Q signals to different filter units.

5. The multifunctional multimode filter according to claim 1 or 4, characterized in that: The filter includes a first filter unit and a second filter unit, both of which include a first-stage filtering module and a second-stage filtering module. The first filter unit corresponds to the I path of the analog I / Q signal and is used to filter the I path differential signal. The second filter unit corresponds to the Q path of the analog I / Q signal and is used to filter the Q path differential signal.

6. The multifunctional multimode filter according to claim 5, characterized in that: There are two of each of the DC offset compensation module, the orthogonal switching module, the notch module, and the operational amplifier bias adjustment module, which are respectively arranged in the first filter unit and the second filter unit; The two notch modules are respectively located between the first-stage filter module and the second-stage filter module in the first filter unit, and between the first-stage filter module and the second-stage filter module in the second filter unit. The notch modules are formed by two groups of resistor and capacitor circuits connected in series.

7. The multifunctional multimode filter according to claim 6, characterized in that: The notch module includes a first circuit connected to the positive pole of the output end of the first-stage filter module and the positive pole of the input end of the second-stage filter module, and a second circuit connected to the negative pole of the output end of the first-stage filter module and the negative pole of the input end of the second-stage filter module. The first circuit and the second circuit both include a resistance circuit and a first capacitor in parallel, a second capacitor and a second resistor connected in series with the resistance circuit and the first capacitor. The first circuit and the second circuit are connected in series with each other. The resistor located between the first circuit and the positive pole of the input end of the second-stage filter module in the filter forms the first adjustable resistor of the notch module, and the resistor located between the second circuit and the negative pole of the input end of the second-stage filter module in the filter forms the second adjustable resistor of the notch module.

8. The multifunctional multimode filter according to claim 5, characterized in that: The multifunctional multimode filter further comprises: The orthogonal offset module is used to cross-merge at least four analog I / Q signals of the filter when the filter is switched to the complex filter mode to achieve complex filtering.

9. The multifunctional multimode filter according to claim 8, characterized in that: The orthogonal offset module has a switch array, and multiple switch pairs in the switch array are respectively connected to the positive or negative poles of the input and output ends of the first filter unit and the second filter unit. Multiple different resistance circuits are connected between each switch pair. The two switches in the switch pair adjust the orthogonal frequency offset by turning on different resistance circuits to achieve filtering of different intermediate frequency signals.

10. The multifunctional multimode filter according to claim 1, characterized in that: The system further includes an automatic bandwidth calibration module, the automatic bandwidth calibration module including a charging module formed by a first-stage filtering module, a discharging module connected to the charging module, and an RC calibration logic module connected to the discharging module, the RC calibration logic module including a comparator, a latch, and a data analyzer connected in sequence, the data analyzer being connected to a capacitor in the charging module; When the filter starts calibration, the charging module charges, and then the analog I-channel or Q-channel signal obtained by the charging module is coupled to the data analyzer through the discharge module to obtain the capacitance size analysis result in the charging module. The capacitance size analysis result represents whether the current value of the capacitance is too large or too small. The data analyzer generates a corresponding adjustment value based on the capacitance size analysis result, and inputs the adjustment value into the capacitance of the charging module to adjust the value of the capacitance.

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