Filter circuit, automatic tuning circuit, filter adjustment circuit and adjustment method

Abstract

The application discloses a filter circuit, an automatic tuning circuit, a filter adjusting circuit and an adjusting method, which are simple and reasonable in structural design, can reduce the chip area, have a multi-channel selection function, can simultaneously meet the requirements of high-bandwidth gain, low power consumption and the like, and the filter circuit structure comprises a three-order reconfigurable gm-c complex band-pass filter circuit, a reconfigurable bias circuit structure and an automatic tuning circuit structure; the integral structure automatic tuning circuit is connected with the three-order reconfigurable gm-c complex band-pass filter through the reconfigurable bias circuit; the integral structure automatic tuning circuit is used for generating a resistance array control word to control the reconfigurable bias circuit; the reconfigurable bias circuit is used for generating a bias voltage for the three-order reconfigurable gm-c complex band-pass filter; and a method for adjusting the center frequency and the bandwidth of the three-order reconfigurable gm-c complex band-pass filter by using the reconfigurable bias circuit structure and the automatic tuning circuit is provided.

Description

Technical Field

[0001] This invention relates to the field of filter technology, specifically to a filter circuit, an automatic tuning circuit, a filter adjustment circuit, and an adjustment method. Background Technology

[0002] Currently, the commonly used RF transceiver architectures in RF transceiver systems mainly include zero-IF (zero intermediate frequency) and low-IF (low intermediate frequency) architectures. Zero-IF receivers do not have image signals, but they suffer from 1 / f noise and DC offset. The intermediate frequency filter is a low-pass filter, which has a simple circuit and low power consumption. Therefore, low-IF architectures are typically used in narrowband communication. The intermediate frequency filter can filter out image interference signals after mixing in the receiving system. Simultaneously, channel selection is required in multi-channel standards. Therefore, a reconfigurable complex bandpass filter with channel selection function plays an important role in low-IF receivers. However, there are few bandpass filters in the current technology that can achieve multi-channel selection.

[0003] Active RC filters are a common implementation of traditional integrated complex filters. They are widely used in practical circuits due to their large input dynamic range and good linearity. However, active RC filters have the following drawbacks: (1) In order to minimize the minimum phase error and other nonlinear distortions at the unity gain frequency, the gain bandwidth of the operational amplifier needs to be 20 to 30 times higher than the cutoff frequency of the filter. However, due to the limitation of low power consumption, it is difficult to obtain a high gain bandwidth of the operational amplifier. (2) When the operational amplifier operates in closed loop, the power consumption is larger compared to the open-loop operation of the gm-c filter. At the same time, the gm unit in the gm-c filter is a transconductance amplifier, which is a voltage-to-current conversion circuit. When the gm-c filter is working, the input voltage can be converted into current output through the gm unit, and then the current to voltage conversion can be achieved by charging and discharging the capacitor. However, the filters in the existing technology contain multiple resistors and capacitors, which are complex in structure and occupy a large chip area, which cannot meet the miniaturization requirements of integrated circuit chips. Summary of the Invention

[0004] To address the problems of existing filters having complex structures, including resistors and capacitors that occupy a large chip area, and being limited by power consumption to achieve a large bandwidth or prone to generating high power consumption, this invention provides a filter circuit structure and method. Its structure design is simple and reasonable, which can reduce the chip area occupied, while having a multi-channel selection function, and can simultaneously meet the requirements of high broadband gain and low power consumption.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A filter adjustment circuit includes a bandpass filter, a bias circuit structure, and an automatic tuning circuit structure. The bandpass filter is a third-order reconfigurable gm-c complex bandpass filter; the bias circuit is a reconfigurable bias circuit; and the automatic tuning circuit is an integral structure automatic tuning circuit. The integral structure automatic tuning circuit is connected to the third-order reconfigurable gm-c complex bandpass filter through the reconfigurable bias circuit. The integral structure automatic tuning circuit generates a resistor array control word to control the reconfigurable bias circuit, and the reconfigurable bias circuit generates a bias voltage for use by the third-order reconfigurable gm-c complex bandpass filter.

[0007] A further feature of the filter adjustment circuit is that,

[0008] It also includes a control word decoding circuit, which decodes the input filter control word to obtain a bandwidth control word, a center frequency control word, and a center frequency positive / negative control word. The bandwidth control word is used to adjust the bandwidth of the integral structure automatic tuning circuit, and the center frequency control word and the center frequency positive / negative control word are used to adjust the center frequency and the sign of the center frequency of the third-order reconfigurable gm-c complex bandpass filter.

[0009] A filter circuit is disclosed, wherein the filter is a third-order reconfigurable gm-c complex bandpass filter. The structure includes an I-channel, a Q-channel, and a cross-coupling module. The I-channel and Q-channel are used to filter differential signals, respectively. The circuit is characterized by further including a switching module, which includes a linkage switch and a selection switch. The I-channel and Q-channel each include a third-order gm-c low-pass filter. The I-channel is connected to the cross-coupling module via the linkage switch, and the Q-channel is connected to the cross-coupling module via the selection switch.

[0010] The linkage switch is used to control the on / off state of the cross-coupling module, the sorting switch is used to control the coupling direction of the cross-coupling module, the linkage switch controls the center frequency of the bandpass filter, and the sorting switch controls the sign of the center frequency.

[0011] A further feature of the filter circuit structure is that...

[0012] The gm-c third-order low-pass filter includes a first-order low-pass filter and a second-order low-pass filter.

[0013] The cross-coupling module includes at least three cross-coupling units;

[0014] The cross-coupling unit includes a first cross-coupling unit, a second cross-coupling unit, and a third cross-coupling unit;

[0015] The number of the linkage switch and the sorting switch is the same as the number of the cross-coupling units included in the cross-coupling module;

[0016] The linkage switch includes switch S array0 S array1 Switch S array2 Switch S array3 The sorting switches include a first sorting switch, a second sorting switch, and a third sorting switch, and the I-channels are respectively connected through the switches S. array1 Switch S array2 Switch S array3 One end of the first cross-coupling unit, the second cross-coupling unit, and the third cross-coupling unit is connected to one end of the first cross-coupling unit, the second cross-coupling unit, and the third cross-coupling unit, respectively, and the other end of the first cross-coupling unit, the second cross-coupling unit, and the third cross-coupling unit is connected to the Q-channel through the first sorting switch, the second sorting switch, and the third sorting switch, respectively.

[0017] The first sorting switch, the second sorting switch, and the third sorting switch each include switches S1 to S4;

[0018] The first-order low-pass filter, the second-order low-pass filter, and the cross-coupling unit all include gm units;

[0019] The cross-coupled unit includes at least two coupled gm units.

[0020] An automatic tuning circuit, wherein the automatic tuning circuit is an integral structure automatic tuning circuit, comprising a filter control switch, a resistor, a capacitor C, and a bias circuit, characterized in that the integral structure automatic tuning circuit is connected to the filter through the filter control switch, the resistor, the capacitor C, and the bias circuit; the filter control switch includes S10 and S20; the resistor is an adjustable resistor R; the bias circuit is used to generate a bias voltage Vref (the bias voltage Vref is a reference voltage generated when the voltage across the resistor R0 is equal to that across the gm unit after adjustment by the bias circuit); the bias voltage Vref is connected to the positive input terminal of the filter; the negative input terminal of the filter is connected to a voltage source through the adjustable resistor R and the filter control switch S10; and the negative input terminal of the filter is connected to the Control Logic through the adjustable resistor R.

[0021] The negative input terminal of the filter is grounded through the capacitor C connected in parallel and the filter control switch S20.

[0022] A further feature of the integral structure automatic tuning circuit is that...

[0023] The adjustable resistor is controlled by switch SW to change its resistance value. Switch SW is a SW<4:0> sorting switch.

[0024] The adjustable resistors have tuning values ​​of 1 / 2R, 1 / 4R, 1 / 8R, 1 / 16R, and 1 / 32R.

[0025] The tuning range of the resistor is 0.5R to 1.5R.

[0026] A method for adjusting a third-order reconfigurable gm-c complex bandpass filter using the aforementioned integral structure automatic tuning circuit and reconfigurable bias circuit, characterized in that the method includes:

[0027] a1. Close the switch S2 to reset the voltage of the capacitor C to 0;

[0028] a2. Open the switch S2 and close the switch S1, so that the voltage of the voltage source VDD charges the capacitor C through the switch S1 and the adjustable resistor R;

[0029] a3. After a fixed delay T, determine whether the voltage V across the capacitor is greater than the bias voltage Vref.

[0030] a31. If the voltage V is greater than the bias voltage Vref, it indicates that the time constant is too small. In this case, increase the adjustable resistor R.

[0031] a32. If the voltage V is less than the bias voltage Vref, then the control word is locked and the control word is transmitted to the resistor control bit of the reconfigurable bias circuit.

[0032] A bias circuit structure for the filter, the bias circuit structure including an amplifier, a gm unit, a capacitor, a switch, a voltage source VDD, a resistor R0, and a current mirror circuit, characterized in that the bias circuit is a reconfigurable bias circuit, the current mirror circuit includes a first current mirror circuit and a second current mirror circuit, the voltage source VDD is connected to the positive input terminal and the first current input terminal of the amplifier through the first current mirror circuit, the voltage source VDD is connected to the negative input terminal and the second current input terminal of the amplifier through the second current mirror circuit, and the second current mirror circuit is connected to the output terminal of the amplifier through the gm unit.

[0033] A further feature of the reconfigurable bias circuit is that:

[0034] The first current mirror circuit includes transistors M1 and M2, M3 and M4, M6 and M7 with their gates connected and mirrored. The second current mirror circuit includes transistors M8 and M9, M10 and M11, M13 and M14 with their gates connected and mirrored. The transistors M1 to M7 in the first current mirror circuit are current mirror structures, and the transistors M8 to M14 in the second current mirror circuit are current mirror structures.

[0035] The first current input terminal is connected to the gates of transistors M1 and M2, and the drain of transistor M1. The gates of transistors M3 and M4 are connected to the drain of transistor M6. The gates of transistors M6 and M7 are connected to the gate of transistor M5. The drain of transistor M2 is connected to the drain of transistor M5. The drain of transistor M4 is connected to the drain of transistor M7 and the positive input terminal of the amplifier via resistor R0. The negative input terminal of the amplifier is connected to the drain of transistor M14 and gm. The positive terminal of the unit is connected to the positive terminal of the unit. The gates of transistors M14 and M13 are connected to the gate of transistor M12. The drain of transistor M13 is connected to the base of transistors M10 and M11 and the drain of transistor M10. The drain of transistor M11 is connected to the negative terminal of the gm unit. The drain of transistor M12 is connected to the drain of transistor M9. The gates of transistors M9 and M8 are connected to the second current input terminal. The sources of transistors M5, M6, M7, M14, M13, and M12 are connected to the voltage source VDD. The sources of transistors M1, M2, M3, M4, M11, M10, M9, and M8 are grounded.

[0036] A method for adjusting the gm value of the gm unit of the filter using the bias circuit, characterized in that the method includes: external currents I1 and I2 being supplied to the bias circuit through the first current input terminal and the second current input terminal, respectively;

[0037] The currents I1 and I2 are mirrored proportionally to transistors M2 and M9, respectively.

[0038] The filter or modulator is reconfigurable, meaning that the current flowing through the gm unit and the resistor R0 is controlled by an ergodic method, thereby controlling the gm value to change proportionally, while simultaneously determining whether the voltage across the resistor R2 and the gm unit is the same or close to it.

[0039] If the voltages are not the same, obtain the voltage difference between the resistor R2 and the gm unit;

[0040] The voltage difference is amplified by the amplifier to generate a corresponding bias voltage Vb. The current of the gm unit is then fed back and tuned by the bias voltage Vb until the bias voltage stabilizes and the voltage across the resistor R0 and the gm unit is equal.

[0041] Its further feature is that,

[0042] The current of the gm unit is fed back and tuned by the bias voltage Vb. If the voltage at the positive input terminal of the amplifier is greater than the voltage at the negative input terminal, it means that the resistance value R0 is greater than the reciprocal of the gm value, i.e., R0 > 1 / gm. The voltage difference between the resistor R0 and the gm unit is amplified by the amplifier to generate the bias voltage of the gm unit. The current flowing through the gm unit increases, and the gm value increases. Conversely, the gm value decreases until the bias voltage stabilizes and the voltage across the resistor R0 and the gm unit is equal.

[0043] The gm value of the gm unit is calculated using the transconductance formula, which is:

[0044]

[0045] Wherein, gm is the transconductance value of the gm unit, i.e., the gm value, and R0 is the resistance value of the resistor R0. gm I is the current flowing through the gm unit. R0 The current flowing through the resistor R0;

[0046] The initial control string for the traversal method is 00000.

[0047] A method for adjusting the center frequency and bandwidth of a third-order reconfigurable GM-C complex bandpass filter is disclosed. This method is based on a control word, a linkage switch and a selection switch, an integral structure automatic tuning circuit, and a bias circuit. The filter operates in two modes: a low-pass filter mode and a complex bandpass filter mode. The control word and linkage switch control the filter's operation in either mode. The linkage switch controls the on / off state of the cross-coupling module. When one of the linkage switches is closed, the bandpass filter operates in complex bandpass filter mode; when all linkage switches are open, the filter operates in low-pass filter mode. The selection switch controls the coupling direction of the cross-coupling module. The linkage switch controls the center frequency of the bandpass filter, and the selection switch controls the sign of the center frequency.

[0048] Its further feature is that,

[0049] Controlling the center frequency of the bandpass filter via the linkage switch includes:

[0050] The switch S in the linkage switch array0 S array1 Switch S array2 Switch S array3 S in the form of a control switch array arra y<3:0> action;

[0051] The control switch array S array <3:0> includes at least four operating states: the S array <3:0>=0001、S array <3:0>=0010、S array <3:0>=0100、S array <3:0> = 1000;

[0052] The cross-coupling module includes a cross-coupling unit array, which is connected to the control switch array S. array The cross-coupled unit array corresponding to <3:0> includes G array <0> G array <1> G array <2> G array <3> ;

[0053] When the control switch array mode S array When <3:0>=0001, the cross-coupled unit array G is selected. array <0> At this time, the center frequency is f lF When the control switch array mode S array When <3:0>=0010, the cross-coupled unit array G is selected. array <1> At this time, the center frequency is 2f IF When the control switch array mode S array When <3:0>=0100, the cross-coupled unit array G is selected. array <2> At this time, the center frequency is 3f IF When the control switch array mode S array When <3:0>=1000, the cross-coupled unit array G is selected. array <3> At this time, the center frequency is 4f IF ;

[0054] The sign of the center frequency of the bandpass filter is controlled by the switching states of switches S1 to S4 in the sorting switches, including: if switches S1 and S2 in the first, second, and third sorting switches are closed, and switches S3 and S4 are open, the center frequency is negative; if switches S3 and S4 are closed, and switches S1 and S2 are open, the center frequency is positive.

[0055] The control word includes the resistor array control word, the center frequency control word, and the center frequency positive / negative control word. The resistor array control word, the center frequency control word, and the center frequency positive / negative control word include the control word LPF_en, the control word WideBW_LPF_en, the control word WideBW_LPF_en, and the control word CBPF_band_sel. The control words LPF_en, WideBW_LPF_en, WideBW_LPF_en, and CBPF_band_sel each include two states: 0 and 1.

[0056] When the control word LPF_en is 1, the two sides of the cross-coupled GM unit are disconnected, and the filter becomes a low-pass filter. When the control word LPF_en is 1 and the control word WideBW_LPF_en is 1, the filter enters a large-bandwidth low-pass filter mode. If the control word LPF_en is 1, and the control word WideBW_LPF_en is 1 and the control word WideBW_LPF_en is 0, the control word CBPF_band_sel controls the bandwidth of the low-pass filter. If the control word CBPF_band_sel is 1, the bandwidth of the low-pass filter is 2f. BW If the control word CBPF_band_sel is 0, then the bandwidth of the low-pass filter is f kHz. BW kHz;

[0057] The resistor array control word, center frequency control word, and center frequency positive and negative control word also include control words IQ_swap_sel and CBPF_if_sel. The array composed of control words IQ_swap_sel, CBPF_if_sel, and CBPF_band_sel controls the working mode of the filter, so that the filter is in the complex bandpass filter mode, and at the same time adjusts the center frequency and bandwidth of the complex bandpass filter.

[0058] When the control word LPF_en is 0 and the control word WideBW_LPF_en is also 0, the filter enters the complex bandpass filter mode. The center frequency and bandwidth of the complex bandpass filter are adjusted by an array composed of the control words IQ_swap_sel, CBPF_if_sel, and CBPF_band_sel, i.e., the channel of the complex bandpass filter is selected, allowing the complex bandpass filter to operate in at least 11 modes. The array composed of the control words CBPF_if_sel and CBPF_band_sel is represented as a control word array.<CBPF_band_sel,CBPF_if_sel> ;

[0059] Channel selection for the complex bandpass filter includes: first, determining the sign of the center frequency of the complex bandpass filter using the control word IQ_swap_sel; if the control word IQ_swap_sel is 0, then the center frequency of the complex bandpass filter is positive. If the control word array...<CBPF_band_sel,CBPF_if_sel> If the value is 0, then the center frequency of the complex bandpass filter is f. IF kHz, the bandwidth is + / -f BW kHz; if the control word array<CBPF_band_sel,CBPF_if_sel> If the value is 0 or 1, then the center frequency of the complex bandpass filter is 3f. 1F kHz, the bandwidth is + / -f BW kHz; if the control word array<CBPF_band_sel,CBPF_if_sel> The value is 10, and the center frequency of the complex bandpass filter is 2f. IF kHz, bandwidth of + / -2f BW kHz; if the control word array<CBPF_band_sel,CBPF_if_sel> If the value is 11, then the center frequency of the complex bandpass filter is 4f. IF kHz, bandwidth of + / -2f BW kHz;

[0060] If the control word IQ_swap_sel is 1, then it is a complex bandpass filter with a negative center frequency.<CBPF_band_sel,CBPF_if_sel> The value is 00, and the filter has a center frequency of -f. IF kHz, the bandwidth is + / -f BWA complex bandpass filter of kHz; if the control word<CBPF_band_sel,CBPF_if_sel> If the value is 0 or 1, then the filter has a center frequency of -3fIFkHz and a bandwidth of + / -f BW A complex bandpass filter of kHz; if the control word<CBPF_band_sel,CBPF_if_sel> The value is 10, and the filter has a center frequency of 2f. IF kHz, bandwidth of + / -2f BW A complex bandpass filter of kHz; if the control word<CBPF_band_sel,CBPF_if_sel> If the value is 11, then the filter has a center frequency of -4f. IF kHz, bandwidth + / -2f BW A complex bandpass filter of kHz.

[0061] The above-mentioned structure of the present invention can achieve the following beneficial effects: 1. The switching module is equipped with a linkage switch and a sorting switch, which enables the gm-c third-order low-pass filter and cross-coupling module in the I-channel and Q-channel to work in an open-loop state. It does not require the connection of multiple resistors and capacitors to meet the integration or transfer function function of the filter, which simplifies the structure of the bandpass filter, reduces the chip area, and reduces power consumption. The linkage switch in the switching module is used to control the on and off of the cross-coupling module, and the sorting switch is used to control the coupling direction of the cross-coupling module. Therefore, the center frequency and the positive and negative values ​​of the center frequency of the filter can be adjusted through the linkage switch and the sorting switch, so that the filter can work in different working modes, thereby meeting the multi-channel selection of the filter and the filtering requirements of the multi-channel signal of the communication chip.

[0062] 2. By using control words, linkage switches, and selection switches, the filter can operate in either low-pass filter mode or complex band-pass filter mode. The linkage switches are used to control the on / off state of the cross-coupling module, the selection switches are used to control the coupling direction of the cross-coupling module, and the control words are used for channel selection control of the filter, thereby realizing the switching of different operating modes of the filter and meeting the filtering requirements of multi-channel signals of the communication chip.

[0063] 3. It also includes an integral structure automatic tuning circuit and a reconfigurable bias conversion circuit connected to the integral structure automatic tuning circuit. The integral structure automatic tuning circuit is used to calibrate the electrical signal of the reconfigurable bias conversion circuit. By calibrating the reconfigurable bias circuit, a control word for controlling the filter is obtained. Through different control words, linkage switches, and sorting switches, the conversion of different working modes of the filter is realized, which meets the filtering requirements of multi-channel signals of the communication chip. The reconfigurable bias conversion circuit can provide bias voltage for the integral structure automatic tuning circuit with fewer resistors, capacitors and corresponding connecting lines. Compared with the existing bias conversion circuit, the circuit structure is simple and the investment cost is reduced.

[0064] 4. When using an integral structure automatic tuning circuit to obtain the control word for adjusting the filter's operating mode, calibration is performed when the integral structure automatic tuning circuit is powered on. After calibration, it is turned off, and the control word obtained for resistor R is given to the resistor array R0 in the reconfigurable bias conversion circuit to calibrate the gm value of each gm unit in the filter. At the same time, the calibration of the overall complex bandpass filter is completed, giving the complex bandpass filter a high degree of reconfigurability and enabling the switching of multiple operating modes. This meets the filtering requirements of multi-channel signals in communication chips and improves the versatility of the filter.

[0065] 5. In the reconfigurable bias circuit, the transconductance value of the gm unit is converted into the value of the resistor R0 in the bias circuit, so that the reconfigurable bias circuit can meet the tuning requirements of different automatic tuning circuits. Therefore, when the reconfigurable bias circuit and the integral structure automatic tuning circuit are applied to the complex bandpass filter, different control words can be generated to switch the working mode of the filter, further satisfying the multi-channel conversion and multi-channel signal filtering requirements of the filter, while improving the filtering effect of the filter. Attached Figure Description

[0066] Figure 1 This is a block diagram of the third-order reconfigurable gm-c complex bandpass filter of the present invention;

[0067] Figure 2 This is a circuit schematic diagram of the third-order reconfigurable gm-c complex bandpass filter circuit of the present invention;

[0068] Figure 3 This is a circuit diagram of the automatic tuning circuit of the integral structure of the present invention;

[0069] Figure 4 This is a circuit diagram of the reconfigurable bias circuit of the present invention. Detailed Implementation

[0070] See Figure 2A filter circuit is disclosed, wherein the filter is a third-order reconfigurable gm-c complex bandpass filter. The filter circuit includes an I-channel 1, a Q-channel 2, a cross-coupling module 3, and a switching module. The I-channel 1 and Q-channel 2 are used to filter differential signals, respectively. The switching module includes a linkage switch 4 and a sorting switch 5. The I-channel 1 is connected to the cross-coupling module 3 through the linkage switch 4, and the Q-channel 2 is connected to the cross-coupling module 3 through the sorting switch 4. The linkage switch 4 is used to control the on / off state of the cross-coupling module 3, and the sorting switch 5 is used to control the coupling direction of the cross-coupling module 3. The center frequency of the filter is controlled by the linkage switch 4, and the sign of the center frequency is controlled by the sorting switch 5.

[0071] Channel 1 (I-channel) and Channel 2 (Q-channel) each include a gm-c third-order low-pass filter, which includes a first-order low-pass filter and a second-order low-pass filter. The cross-coupling unit includes a first cross-coupling unit 31, a second cross-coupling unit 32, and a third cross-coupling unit 33. The number of linkage switches 4 and sorting switches 5 is the same as the number of cross-coupling units included in the cross-coupling module 3. The first-order low-pass filter, the second-order low-pass filter, and the cross-coupling unit all include gm units, which are used for voltage-to-current conversion. Each gm unit includes Gm1, Gm2, and Gm. In this embodiment, the cross-coupling unit includes two cross-coupled Gm units. The first-order low-pass filter and the second-order low-pass filter each include Gm1 and Gm2. The values ​​of Gm1, Gm2, and Gm in the gm unit are related to the filter type. In this embodiment, the passband ripple is selected as 0.3 dB. For the Chebyshev type filter, the calculated values ​​are Gm1 = 0.733 μS; Gm2 = 1.138 μS; and Gm = 0.78 μS.

[0072] The linkage switch 4 includes switch S array1 Switch S array2 Switch S array3 The sorting switch 5 includes a first sorting switch, a second sorting switch, and a third sorting switch. The I-channel is respectively connected to switch S. array1 Switch S array2 Switch S array3 One end of the first cross-coupling unit, the second cross-coupling unit, and the third cross-coupling unit is connected to one end of the first cross-coupling unit, the second cross-coupling unit, and the third cross-coupling unit. The other ends of the first cross-coupling unit, the second cross-coupling unit, and the third cross-coupling unit are respectively connected to the Q-channel through the first sorting switch, the second sorting switch, and the third sorting switch. The first sorting switch, the second sorting switch, and the third sorting switch each include switches S1 to S4.

[0073] See Figure 4A reconfigurable bias circuit for the aforementioned third-order reconfigurable gm-c complex bandpass filter is disclosed. The reconfigurable bias circuit includes an amplifier, a gm unit, a capacitor, a switch, a voltage source VDD, a resistor R0, and a current mirror circuit. The current mirror circuit includes a first current mirror circuit and a second current mirror circuit. The voltage source VDD is connected to the positive input terminal and the first current input terminal of the amplifier through the first current mirror circuit. The voltage source VDD is connected to the negative input terminal and the second current input terminal of the amplifier through the second current mirror circuit. The second current mirror circuit is connected to the output terminal of the amplifier through the gm unit.

[0074] The first current mirror circuit includes transistors M1 and M2, M3 and M4, M6 and M7 with their gates connected and mirrored. The second current mirror circuit includes transistors M8 and M9, M10 and M11, M13 and M14 with their gates connected and mirrored. Transistors M1 to M7 in the first current mirror circuit are current mirror structures, and transistors M8 to M14 in the second current mirror circuit are current mirror structures.

[0075] The first current input terminal is connected to the gates of transistors M1 and M2, and the drain of transistor M1. The gates of transistors M3 and M4 are connected to the drain of transistor M6. The gates of transistors M6 and M7 are connected to the gate of transistor M5. The drain of transistor M2 is connected to the drain of transistor M5. The drain of transistor M4 is connected to the drain of transistor M7 and the positive input terminal of the amplifier via resistor R0. The negative input terminal of the amplifier is connected to the drain of transistor M14 and the positive terminal of the gm unit. The gates of transistors M14 and M13 are connected to the gate of transistor M12. The drain of transistor M13 is connected to the base of transistors M10 and M11, and the drain of transistor M10. The drain of transistor M11 is connected to the negative terminal of the gm unit. The drain of transistor M12 is connected to the drain of transistor M9. The gates of transistors M9 and M8 are connected to the second current input terminal. Transistors M5, M6, and M7... The sources of M14, M13, and M12 are connected to the voltage source VDD, while the sources of transistors M1, M2, M3, M4, M11, M10, M9, and M8 are grounded.

[0076] A method for adjusting the gm value of the gm unit of the above-mentioned bandpass filter using a bias circuit, the method comprising: external currents I1 and I2 being supplied to the bias circuit through a first current input terminal and a second current input terminal, respectively;

[0077] Currents I1 and I2 are mirrored proportionally to transistors M2 and M9, respectively.

[0078] Reconfigurable control of filters or modulators refers to controlling the current flowing through the gm unit and resistor R0 using an ergodic method, thereby controlling the gm value to change proportionally, while simultaneously determining whether the voltages across resistor R2 and the gm unit are the same or close:

[0079] If the voltages are not the same, obtain the voltage difference between resistor R2 and unit gm;

[0080] The voltage difference is amplified by an amplifier to generate a corresponding bias voltage Vb. The current of the gm unit is then fed back and tuned by the bias voltage Vb until the bias voltage stabilizes and the voltage across the resistor R0 and the gm unit is equal.

[0081] The current of the gm unit is fed back and tuned by the bias voltage Vb. If the voltage at the positive input terminal of the amplifier is greater than the voltage at the negative input terminal, it means that the resistance value R0 is greater than the reciprocal of the gm value, i.e., R0 > 1 / gm. The voltage difference between resistor R0 and the gm unit is amplified by the amplifier to generate the bias voltage of the gm unit. The current flowing through the gm unit increases, and the gm value increases. Conversely, the gm value decreases until the bias voltage stabilizes and the voltage across resistor R0 and the gm unit is equal.

[0082] The gm value of the gm unit is calculated using the transconductance formula, which is:

[0083]

[0084] Where gm is the transconductance of the gm unit, i.e., the gm value, R0 is the resistance value of the resistor R0, Igm is the current flowing through the gm unit, and IR0 is the current flowing through the resistor R0.

[0085] In this reconfigurable bias switching circuit, the gm unit is connected as a resistor, and transistors M1 and M2 form a current mirror circuit to proportionally mirror the external input current I1 onto NMOS transistor M2. Similarly, M8 and M9 form a current mirror circuit to proportionally mirror the external input current I2 onto NMOS transistor M9. In the above diagram, M5 and M12 are parallel PMOS arrays. Switches T1<1:0> and T2<1:0> control the current mirrored from transistors M5 and M12 to M6 and M13. (Reconfigurable control refers to controlling the current through the gm unit or resistor R0 to proportionally change the gm value, thereby achieving reconfigurable control of the filter circuit.) The voltage across resistor R0 and the gm unit should be the same. If they are not, the voltage difference enters the amplifier, is amplified by the operational amplifier, and generates a corresponding bias voltage Vb. This provides feedback adjustment to the tail current of the gm unit. If the voltage at the positive input terminal of the amplifier is greater than the voltage at the negative input terminal, it indicates that R0 > 1 / gm. The voltage difference between resistor R0 and the gm unit, after amplification, generates the bias voltage Vb of the gm unit. Consequently, the tail current of the gm unit increases, and the gm value increases; conversely, the gm value decreases. It can be inferred that after a period of time, the bias voltage stabilizes, and the voltage across the resistor and the gm unit becomes equal. The formula can be derived.

[0086]

[0087] This conversion circuit transforms the tuning of the GM unit and capacitor into the tuning of the resistor and capacitor.

[0088] See Figure 1 , Figure 3 An integrator structure automatic tuning circuit for the aforementioned third-order reconfigurable gm-c complex bandpass filter includes a filter control switch, a resistor, and a capacitor C. The integrator structure automatic tuning circuit is connected to the complex bandpass filter via a reconfigurable bias circuit. The filter control switch includes S10 and S20, and the resistor is an adjustable resistor R. The reconfigurable bias circuit generates a bias voltage Vref, which is connected to the positive input terminal of the filter. The negative input terminal of the filter is connected to a voltage source via the adjustable resistor R and the filter control switch S10, and is also connected to a control logic via the adjustable resistor R. The negative input terminal of the filter is grounded via the parallel capacitor C and the filter control switch S20.

[0089] The adjustable resistor R's resistance value is changed by a switch SW, which is a SW<4:0> selector switch. The adjustable resistor's tuning values ​​include 1 / 2R, 1 / 4R, 1 / 8R, 1 / 16R, and 1 / 32R. The SW<4:0> selector switch is used to switch and adjust the various tuning values ​​of the adjustable resistor R and to tune the capacitor. Figure 3Vref is the voltage under unbiased conditions. The resistor R is controlled using a traversal method and a switch SW. Since the maximum deviation may reach 50%, the capacitor's tuning range is set to 0.5R to 1.5R during control. The initial control string is 00000, and the process is repeated upwards. The workflow of this automatic tuning circuit is as follows:

[0090] a1. Close switch S2 to reset the voltage of capacitor C to 0;

[0091] a2. Open switch S2 and close switch S1 to allow the voltage from voltage source VDD to charge capacitor C through switch S1 and adjustable resistor R.

[0092] a3. After a fixed delay T, determine whether the voltage V across the capacitor is greater than the bias voltage Vref.

[0093] a31. If the voltage V is greater than the bias voltage Vref, it means that the time constant is too small. In this case, increase the adjustable resistor R.

[0094] a32. If the voltage V is less than the reference voltage Vref, the control word will be locked and the control will be set to the resistor control bit transmitted to the filter.

[0095] This type of automatic tuning circuit has a simple structure and is therefore commonly used in active RC filters and modulators. However, since the GM-C circuit only contains GM units and capacitors, this tuning method cannot usually be used. Due to the bias circuit described above, which converts the size of the GM unit into the size of the resistor in the bias circuit, the complex bandpass filter of this invention can also use this automatic tuning circuit.

[0096] See Figure 1The aforementioned reconfigurable bias circuit 10, integral structure automatic tuning circuit 11, bias voltage adjustment method, and bandwidth automatic tuning method are applied to a third-order reconfigurable gm-c complex bandpass filter to adjust the center frequency and bandwidth of the filter. The filter adjustment method is based on the aforementioned integral structure automatic tuning circuit 11, reconfigurable bias circuit 10, third-order reconfigurable gm-c complex bandpass filter 12, and existing control word decoding circuit 13. The control word is input to the control word decoding circuit 13, which decodes the control word signals of the reconfigurable bias conversion circuit 10 and the third-order reconfigurable gm-c complex bandpass filter 12. Simultaneously, the integral structure automatic tuning circuit 11 performs calibration upon power-on and is turned off after calibration. The resulting control word for the resistors is given to the resistor array in the reconfigurable bias conversion circuit 10 to calibrate the size of the gm unit, thus completing the calibration of the overall complex bandpass filter. The control word decoding circuit 13 and the decoding of the input filter control word through the control word decoding circuit 13 both adopt existing technologies. The input filter control word is decoded to obtain the bandwidth control word, center frequency control word, and center frequency positive / negative control word. The bandwidth control word is used to tune the bandwidth of the integrator structure automatic tuning circuit 22. The center frequency control word and the center frequency positive / negative control word are used to adjust the center frequency and the positive / negative of the center frequency of the third-order reconfigurable gm-c complex bandpass filter 12. The integrator structure automatic tuning circuit 11 is used to generate a resistor array control word to adjust the bias voltage of the reconfigurable bias conversion circuit 10. The reconfigurable bias conversion circuit 10 is used to provide a reconfigurable bias voltage for the third-order reconfigurable gm-c complex bandpass filter 12.

[0097] The third-order reconfigurable GM-C complex bandpass filter circuit uses a control word, interlocking switches, and a selection switch to adjust the center frequency and bandwidth of the filter. The third-order reconfigurable GM-C complex bandpass filter operates in two modes: low-pass filter mode and complex bandpass filter mode. The control word and interlocking switches control the on / off state of the cross-coupling module. When one of the interlocking switches is closed, the bandpass filter operates in complex bandpass filter mode; when all interlocking switches are open, the filter is in low-pass filter mode. The selection switch controls the coupling direction of the cross-coupling module. The center frequency of the bandpass filter is controlled by the interlocking switch, and the sign of the center frequency is controlled by the selection switch.

[0098] The center frequency of the bandpass filter is controlled by a linkage switch, including: switch S in the linkage switch. array0 S array1 Switch S array2 Switch S array3 S in the form of a control switch array arrayThe <3:0> operation, in this embodiment, controls the switch array <3:0>, which includes four working states: <3:0> = 0001, S... array <3:0>=0010、S array <3:0>=0100、S array <3:0> = 1000;

[0099] The cross-coupling module includes a cross-coupling unit array and a control switch array S. array The cross-coupled unit array corresponding to <3:0> includes G array <0> G array <1> G array <2> G array <3> ;

[0100] When the control switch array mode S array When <3:0>=0001, select the cross-coupled cell array G. array <0> At this time, the center frequency is f IF When the control switch array mode S array When <3:0>=0010, select the cross-coupled cell array G. array <1> At this time, the center frequency is 2f. IF When the control switch array mode S array When <3:0>=0100, select the cross-coupled cell array G. array <2> At this time, the center frequency is 3f. IF When the control switch array mode S array When <3:0>=1000, select the cross-coupled cell array G. array <3> At this time, the center frequency is 4f. IF .

[0101] The sign of the center frequency of the bandpass filter is controlled by the switching states of switches S1 to S4 in the sorting switches. Specifically, if switches S1 and S2 in the first, second, and third sorting switches are closed while switches S3 and S4 are open, the center frequency is negative. If switches S3 and S4 are closed while switches S1 and S2 are open, the coupling direction of each gm unit in the cross-coupled unit is opposite to that of the previous connection method, and the center frequency is positive.

[0102] The center frequency and bandwidth of the third-order reconfigurable gm-c complex bandpass filter are adjusted using control words. In this application, the center frequency and bandwidth are adjusted using 5 control words to achieve the adjustment of 11 operating modes (functions) of the filter. The relationship between the control words and the filter's function and control effect is shown in the table below:

[0103]

[0104] In the table above, the control words include control word LPF_en, control word WideBW_LPF_en, control word WideBW_LPF_en, and control word CBPF_band_sel; control words LPF_en, WideBW_LPF_en, WideBW_LPF_en, and CBPF_band_sel each include two states: 0 and 1.

[0105] When the control word LPF_en is 1, the cross-coupled GM units are disconnected, and the filter becomes a low-pass filter. When both the control word LPF_en and the control word WideBW_LPF_en are 1, the filter enters the large-bandwidth low-pass filter mode. If the control word LPF_en is 1 and the control word WideBW_LPF_en is 0, the control word CBPF_band_sel controls the bandwidth of the low-pass filter. If the control word CBPF_band_sel is 1, the bandwidth of the low-pass filter is 2f. BW If the control word CBPF_band_sel is 0, then the bandwidth of the low-pass filter is f kHz. BW kHz;

[0106] The control word also includes control words IQ_swap_sel and CBPF_if_sel. The array composed of control words IQ_swap_sel, CBPF_if_sel and CBPF_band_sel controls the working mode of the filter, so that the filter is in complex bandpass filter mode, and at the same time adjusts the center frequency and bandwidth of the complex bandpass filter.

[0107] When both the control word LPF_en and the control word WideBW_LPF_en are 0, the filter enters the complex bandpass filter mode. The center frequency and bandwidth of the complex bandpass filter are adjusted by an array composed of the control words IQ_swap_sel, CBPF_if_sel, and CBPF_band_sel, effectively selecting the channel for the complex bandpass filter. This allows the complex bandpass filter to operate in at least 11 different modes. The array composed of the control words CBPF_if_sel and CBPF_band_sel is represented as the control word array.<CBPF_band_sel,CBPF_if_sel> ;

[0108] Channel selection for the complex bandpass filter includes: First, determining the sign of the center frequency of the complex bandpass filter using the control word IQ_swap_sel. If the control word IQ_swap_sel is 0, the center frequency of the complex bandpass filter is positive. If the control word array...<CBPF_band_sel,CBPF_if_sel> If the value is 0, then the center frequency of the complex bandpass filter is f. IF kHz, bandwidth of + / -f BW kHz; if control word array<CBPF_band_sel,CBPF_if_sel> If the value is 0 or 1, then the center frequency of the complex bandpass filter is 3f. 1F Hz, bandwidth of + / -f BW kHz; if control word array<CBPF_band_sel,CBPF_if_sel> The center frequency of the complex bandpass filter is 2f, which is 10. IF kHz, bandwidth of + / -2f BW kHz; if control word array<CBPF_band_sel,CBPF_if_sel> If the value is 11, then the center frequency of the complex bandpass filter is 4f. IF kHz, bandwidth of + / -2f BW kHz;

[0109] If the control word IQ_swap_sel is 1, then it is a complex bandpass filter with a negative center frequency.<CBPF_band_sel,CBPF_if_sel> The value is 00, and the filter has a center frequency of -f. IF kHz, bandwidth of + / -f BW A complex bandpass filter of kHz; if the control word<CBPF_band_sel,CBPF_if_sel> If the value is 0 or 1, then the filter has a center frequency of -3f. IF kHz, bandwidth of + / -f BW A complex bandpass filter of kHz; if the control word<CBPF_band_sel,CBPF_if_sel> The value is 10, and the filter has a center frequency of -2F. IF kHz, bandwidth of + / -2f BW A complex bandpass filter of kHz; if the control word<CBPF_band_sel,CBPF_if_sel> If the value is 11, then the filter has a center frequency of -4f. IF kHz, bandwidth + / -2f BW A complex bandpass filter of kHz.

[0110] The time constant of a GM-C filter is c / gm. If the GM unit can be made very small, the capacitor area in the GM-C filter can be reduced. Therefore, GM-C is also a cost-effective option for low-frequency filters.

[0111] The above are merely preferred embodiments of this application, and the invention is not limited to the above embodiments. It is understood that other improvements and variations that can be directly derived or conceived by those skilled in the art without departing from the spirit and concept of the invention should be considered to be included within the scope of protection of the invention.

Claims

1. A method for adjusting the center frequency and bandwidth of a filter, the filter being a third-order reconfigurable gm-c complex bandpass filter, the filter circuit comprising a circuit structure including an I-path channel, a Q-path channel, and a cross-coupling module, the I-path channel and the Q-path channel being respectively configured to filter a differential signal, the method being based on a filter circuit, an automatic tuning circuit, and a biasing circuit, the method comprising: adjusting the center frequency and bandwidth of the filter by adjusting the biasing circuit, the automatic tuning circuit, and the filter circuit. It also includes a switch module, the switch module includes linkage switch, sorting switch, the I channel, Q channel respectively includes gm-c third order low pass filter, the I channel is connected with the cross coupling module through the linkage switch, the Q channel is connected with the cross coupling module through the sorting switch; The linkage switch is used for controlling the on-off of the cross coupling module, the sorting switch is used for controlling the coupling direction of the cross coupling module, the center frequency of the filter is controlled through the linkage switch, and the positive and negative of the center frequency is controlled through the sorting switch; The gm-c third order low pass filter includes a first order low pass filter and a second order low pass filter; the cross coupling module includes at least three cross coupling units, the number of the linkage switch and the sorting switch is consistent with the number of the cross coupling units included in the cross coupling module; The first order low pass filter, the second order low pass filter and the cross coupling unit all include a gm unit, and the cross coupling unit includes at least two coupled gm units; The adjustment method is realized based on a control word, the linkage switch and the sorting switch, an integral structure automatic tuning circuit and a bias circuit, the working mode of the filter includes a low pass filter mode and a complex band pass filter mode, the filter works in the low pass filter mode or the complex band pass filter mode through the control word and the linkage switch, when one of the linkage switches is closed, the filter works in the complex band pass filter mode, and when all the linkage switches are disconnected, the filter is in the low pass filter mode; The adjusting method controls the center frequency of the band-pass filter through the linkage switch, and includes: switches S array0 、 array1 、 array2 、 array3 in the linkage switch array <3:0> are controlled; the control switch array mode S array <3:0> includes at least four working states: the S array <3:0> =0001, S array <3:0> =0010, S array <3:0> =0100, S array <3:0> =1000; the cross-coupling module includes a cross-coupling unit array corresponding to the control switch array mode S array <3:0>; the cross-coupling unit array corresponding to the control switch array mode S array <0>, the cross-coupling unit array G array <1>, the cross-coupling unit array G array <2>, the cross-coupling unit array G array <3>; when the control switch array mode S array <3:0> =0001, the cross-coupling unit array G array <0> is selected, at this time, the center frequency is f IF ; when the control switch array mode S array <3:0> =0010, the cross-coupling unit array G array <1> is selected, at this time, the center frequency is 2f IF ; when the control switch array mode S array <3:0> =0100, the cross-coupling unit array G array <2> is selected, at this time, the center frequency is 3f IF ; when the control switch array mode S array <3:0> =1000, the cross-coupling unit array G array <3> is selected, at this time, the center frequency is 4f IF , the sorting switch includes a first sorting switch, a second sorting switch and a third sorting switch, the first sorting switch, the second sorting switch and the third sorting switch respectively include switches S1-S4, the positive and negative of the center frequency of the band-pass filter are controlled through the switch state of the switches S1-S4 in the sorting switch, including: if the switches S1 and S2 in the first sorting switch, the second sorting switch and the third sorting switch are closed, and the switches S3 and S4 are opened, the center frequency is negative, if the switches S3 and S4 are closed, and the switches S1 and S2 are opened, the center frequency is positive; The control word includes a resistance array control word, a center frequency control word and a center frequency positive and negative control word, the resistance array control word, the center frequency control word and the center frequency positive and negative control word include a control word LPF_en, a control word WideBW_LPF_en and a control word CBPF_band_sel; the control word LPF_en, the control word WideBW_LPF_en and the control word CBPF_band_sel all include two states of 0 and 1; When the control word LPF_en is 1, the cross-coupled gm cell across the cross is disconnected, the filter becomes a low-pass filter; when the control word LPF_en is 1, and the control word WideBW_LPF_en is 1, the filter enters a large bandwidth low-pass filter mode; if the control word LPF_en is 1, and the control word WideBW_LPF_en is 0, the control word CBPF_band_sel controls the bandwidth of the low-pass filter, if the control word CBPF_band_sel is 1, the bandwidth of the low-pass filter is 2f BW kHz, if the control word CBPF_band_sel is 0, the bandwidth of the low-pass filter is f BW kHz, the resistance array control word, center frequency control word, center frequency positive and negative control word also includes control word IQ_swap_sel, CBPF_if_sel, through the control word IQ_swap_sel, the control word CBPF_if_sel and the control word CBPF_band_sel form an array to control the working mode of the filter, so that the filter is in the complex band-pass filter mode, and the center frequency and bandwidth of the complex band-pass filter are adjusted; when the control word LPF_en is 0, and the control word WideBW_LPF_en is 0, the filter enters the complex band-pass filter mode, and the center frequency and bandwidth of the complex band-pass filter are adjusted through the control word IQ_swap_sel, the control word CBPF_if_sel and the control word CBPF_band_sel form an array, that is, the channel of the complex band-pass filter is selected, so that the complex band-pass filter is in at least 11 working modes, the array of the control word CBPF_if_sel and the control word CBPF_band_sel is represented as control word array <CBPF_band_sel, CBPF_if_sel>, and the channel of the complex band-pass filter is selected, including: the positive and negative of the center frequency of the complex band-pass filter is determined through the control word IQ_swap_sel, if the control word IQ_swap_sel is 0, the center frequency of the complex band-pass filter is positive; if the control word array <CBPF_band_sel, CBPF_if_sel> is 00, the center frequency of the complex band-pass filter is f IF kHz, the bandwidth is + / - 2f BW kHz; if the control word array <CBPF_band_sel, CBPF_if_sel> is 01, the center frequency of the complex band-pass filter is 3f IF kHz, the bandwidth is + / - f BW kHz; if the control word array <CBPF_band_sel, CBPF_if_sel> is 10, the center frequency of the complex bandpass filter is 2f IF kHz, with a bandwidth of + / - 2f BW kHz; if the control word array <CBPF_band_sel, CBPF_if_sel> is 10, the center frequency of the complex bandpass filter is 2f IF kHz, with a bandwidth of + / - 2f BW kHz; If the control word IQ_swap_sel is 1, then for a complex bandpass filter with a center frequency of -f IF kHz, the filter is a complex bandpass filter with a center frequency of -3f BW kHz and a bandwidth of + / - f IF kHz. If the control word <CBPF_band_sel, CBPF_if_sel> is 10, then the filter is a complex bandpass filter with a center frequency of -2f BW kHz and a bandwidth of + / - 2f IF kHz. If the control word <CBPF_band_sel, CBPF_if_sel> is 11, then the filter is a complex bandpass filter with a center frequency of -4f BW kHz and a bandwidth of + / - 2f IF kHz. If the control word <CBPF_band_sel, CBPF_if_sel> is 11, then the filter is a complex bandpass filter with a center frequency of -4f BW kHz and a bandwidth of + / - 2f 2. The method of claim 1, wherein, The automatic tuning circuit is an integral structure automatic tuning circuit, which includes a filter control switch, a resistance, a capacitor C, a bias circuit and a Control Logic, the integral structure automatic tuning circuit is connected with the filter through the filter control switch, the resistance, the capacitor C and the bias circuit, the filter control switch includes S10 and S20, the resistance is an adjustable resistance R, the bias circuit is used for generating a bias voltage Vref, the bias voltage Vref is connected with a positive input end of the filter, a negative input end of the filter is connected with a voltage source through the adjustable resistance R, the filter control switch S10 and the Control Logic, and the negative input end of the filter is connected with the Control Logic through the adjustable resistance R. The negative input end of the filter is grounded through the capacitor C and the filter control switch S20 in parallel.

3. The method of claim 2, wherein the step of adjusting comprises: The adjustable resistor realizes resistance value conversion through a switch SW, and the switch SW is a SW<4:0> sorting switch; and the tuning resistance value of the adjustable resistor includes 1 / 2R, 1 / 4R, 1 / 8R, 1 / 16R and 1 / 32R.

4. The method of claim 3, wherein the method of adjusting comprises a method of adjusting a biasing circuit using the automatic tuning circuit to adjust the reconfigurable biasing circuit, wherein the method of adjusting comprises: The bias circuit adjustment method comprises: a1, closing the switch S20, resetting the voltage of the capacitor C to 0; a2, opening the switch S20, closing the switch S10, and charging the capacitor C through the switch S10 and the adjustable resistor R by the voltage of the voltage source VDD; a3, delaying a fixed time T, and judging whether the voltage V on the capacitor is greater than the bias voltage Vref, a31, if the voltage V is greater than the bias voltage Vref, it indicates that the time constant of the filter is too small, at this time, the adjustable resistor R is increased; a32, if the voltage V is less than the bias voltage Vref, the control word is locked, and the control word is transmitted to the resistance control bit of the filter.

5. A filter adjustment circuit for implementing the adjustment method of claim 1, characterized by The bias circuit is a reconfigurable bias circuit, the integral structure automatic tuning circuit is connected with the third-order reconfigurable gm-c complex band-pass filter through the reconfigurable bias circuit, the integral structure automatic tuning circuit is used for generating a resistance array control word to control the reconfigurable bias circuit, and the reconfigurable bias circuit is used for generating a bias voltage for the third-order reconfigurable gm-c complex band-pass filter.

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