Heterogeneous integrated BAW bulk acoustic wave radio frequency filter with embedded active inductor

Abstract

The invention discloses a heterogeneous integrated BAW (Bulk Acoustic Wave) radio-frequency filter with an embedded active inductor, which comprises a series trunk and a plurality of parallel branches, and is characterized in that the parallel branches are connected between the series trunk and a ground wire; the series trunk comprises a plurality of series bulk acoustic resonators which are sequentially connected in series; at least one series bulk acoustic wave resonator is spaced between the parallel branches, each parallel branch comprises a parallel bulk acoustic wave resonator and an inductance device which are connected in series, and the inductance device on at least one parallel branch or at least one series branch is an active inductance device. The heterogeneous integrated BAW bulk acoustic wave radio frequency filter comprises an active inductor which is small in size, high in Q value and convenient to regulate and control in inductance value, so that the BAW radio frequency filter provided by the invention is high in quality and good in integration level.

Description

Technical Field

[0001] The present invention belongs to the field of integrated circuits, and in particular relates to a heterogeneous integrated BAW bulk acoustic wave radio frequency filter with an embedded active inductor. Background Art

[0002] In thin film bulk acoustic wave (BAW) RF filters, inductor devices are often used to meet the requirements of special zero-point suppression, impedance matching, insertion loss reduction and other filtering characteristics. Currently, passive inductors are used in BAW RF filters. Passive inductors have the following main disadvantages: (1) Low quality factor. The size of the quality factor is one of the important indicators to measure the performance of an inductor. An inductor with a high quality factor means lower energy storage loss and better frequency selectivity. In general, the quality factor of an on-chip passive inductor is around 10. The quality factor of a passive inductor is low, which seriously reduces the roll-off characteristics, out-of-band suppression and in-band insertion loss of the RF filter. In contrast, the Q value of an active inductor is around 100-1000. (2) Passive inductors have disadvantages such as small inductance values, large chip area, and difficulty in integration. A 3nH passive inductor will occupy a silicon chip area of ​​about 50um*50um. Considering the cost, it is generally difficult to achieve a passive inductor larger than 20nH. The area of ​​active inductors is very small. Under the same inductance value, the area is only 1 / 100-1 / 1000 of that of passive inductors, and the inductance can be electrically adjusted. This makes active inductors a major research hotspot, but there is currently no research on integrating active inductors into BAW RF filters.

[0003] The patent application with publication number CN111200418A discloses a bulk acoustic wave filter and a signal processing device, which relates to the field of filters. The bulk acoustic wave filter includes a series branch and multiple parallel branches; the series branch is composed of a number of series bulk acoustic wave resonators connected in sequence; a parallel branch is connected to the connection node between two adjacent series bulk acoustic wave resonators; each parallel branch includes a first parallel bulk acoustic wave resonator, a second parallel bulk acoustic wave resonator and a first inductor, the first parallel bulk acoustic wave resonator, the second parallel bulk acoustic wave resonator and the first inductor are connected in series in sequence, and the second parallel bulk acoustic wave resonator and the first inductor are simultaneously connected in parallel with at least one of the second inductors; there is mutual inductance between at least two adjacent second inductors connected to different parallel branches; the first inductor and the second inductor are both grounded. This patent application improves the out-of-band suppression of the bulk acoustic wave filter. However, the inductor used in this patent application is a passive inductor.

[0004] The patent application with publication number CN208158552U discloses an active inductor with a high quality factor. The active inductor is a common-source and common-gate grounded active inductor with an on-chip capacitor added thereto, and specifically includes: a first transconductance amplifier, a second transconductance amplifier, a feedback resistor, a first current source, a second current source and an on-chip capacitor; the first and second current sources provide bias currents for the first and second transconductance amplifiers, respectively; the second transconductance amplifier is formed by a common-source and common-gate circuit stacked with two transistors, which improves the gain of the amplifier and thus reduces the loss of the active inductor; the feedback resistor is connected between the input of the first transconductance amplifier and the output of the second transconductance amplifier, which improves the quality factor of the active inductor; an on-chip capacitor is added between the gate and source of the common-gate transistor of the second transconductance amplifier, which increases the equivalent inductance value and reduces the series equivalent resistance, thereby improving the quality factor of the active inductor. However, the active inductor disclosed in this patent application has a low Q value and a high lower limit of the inductance value, which makes it poorly matched with the BAW RF filter. In addition, the active inductor occupies a high area and cannot be used in BAW RF filters. Summary of the invention

[0005] The present invention provides a heterogeneous integrated BAW bulk acoustic wave radio frequency filter with an embedded active inductor. The heterogeneous integrated BAW bulk acoustic wave radio frequency filter includes an active inductor with a small volume, a high Q value, and conveniently regulated inductance, so that the BAW radio frequency filter provided by the present invention has high quality and good integration.

[0006] The present invention provides a heterogeneous integrated BAW bulk acoustic wave radio frequency filter with embedded active inductor, comprising a series trunk and a plurality of parallel branches, wherein the parallel branches are connected between the series trunk and a ground line; The series trunk circuit includes a plurality of series bulk acoustic wave resonators connected in series in sequence; There is at least one series BAW resonator between the parallel branches, and the parallel branches include a series-connected parallel BAW resonator and an inductor, wherein the inductor on at least one parallel branch or the series branch is an active inductor.

[0007] Preferably, the active inductor device comprises: The gate of the first NMOS tube is connected to the drain of the third NMOS tube, the source of the first NMOS tube is grounded, and the drain of the first NMOS tube is respectively connected to the input end of the active inductor and the drain of the first current source; The gate of the second NMOS tube is connected to the output end of the active inductor, the source of the second NMOS tube is grounded, and the drain of the second NMOS tube is respectively connected to the gate of the third NMOS tube and one end of the resistor; The drain of the third NMOS tube is also connected to the drain of the second current source, and the source of the third NMOS tube is grounded; The source of the first current source, the source of the second current source and the other end of the resistor are respectively connected to a power source VDD.

[0008] The present invention uses the first NMOS tube as a positive transconductance amplifier, and uses the second NMOS tube and the third NMOS tube as negative transconductance amplifiers. The active inductor is obtained by interconnecting the gate and drain of the first NMOS tube and the third NMOS tube, and the inductance of the active inductor is adjusted in a relatively simple and efficient manner by adjusting the bias voltage applied to the first current source and the second current source, and the resistance value of the resistor. The active inductor provided by the present invention has a high Q value and a small area.

[0009] Compared with the prior art, the present invention adjusts the transconductance value of the positive transconductance amplifier constructed by the first NMOS tube by adjusting the bias voltage applied to the first current source, and adjusts the transconductance value of the negative transconductance amplifier by adjusting the bias voltage applied to the second current source and / or the resistance value of the resistor, and based on the above-mentioned regulation, the regulation of the inductance value can be achieved more efficiently.

[0010] Compared with the active inductor disclosed in CN208158552U, the active inductor of this patent has only one-stage amplification structure, while the active inductor provided by the present invention uses a two-stage amplification structure, which makes the active inductor provided by the present invention have a greater gain, can achieve a lower inductance value, and is more suitable for application in RF filters. Secondly, the maximum Q value of the inductor of this patent can only reach 724.4, and the frequency range of the high Q value is narrow, while the Q value of the active inductor provided by the present invention can reach more than several thousand, and the high Q value range is large, which can perfectly match the RF filter. In addition, the active inductor of this patent includes two current sources plus an NMOS tube that requires voltage bias and a capacitor, while the active inductor provided by the present invention only needs to bias two current sources. The active inductor provided by the present invention requires a smaller area and can be used for single-chip heterogeneous integration of BAW RF filters.

[0011] The present invention also improves the Q value of the active inductor by reducing the real part of the active inductor impedance. The input terminal provided by the present invention is connected to the gate of the second NMOS tube, and then the drain of the second NMOS tube is connected to a resistor to amplify the signal and transmit it to the gate of the third NMOS tube, and the third NMOS tube amplifies the signal again and transmits it to the gate of the first NMOS tube. This is a two-stage amplification structure. In each stage of amplification, the phase of the high-frequency signal lags behind the previous stage. If the phase lag exceeds a certain value, the real part of the impedance of the active inductor will become a negative number. Then, in the process of the real part of the impedance changing from a positive number to a negative number, through certain circuit parameter settings, the impedance can be made positive but very close to zero, and the Q value is equal to the imaginary part divided by the real part, so even if the inductance value is low, a very high Q value can still be achieved.

[0012] Preferably, the first current source is used to provide a first bias current to the first NMOS transistor.

[0013] Further preferably, the first current source is a first PMOS tube, the drain of the first PMOS tube is connected to the drain of the first NMOS tube, the source of the first PMOS tube is connected to the power supply Vdd, and a first bias voltage is applied to the gate of the first PMOS tube, so that the first PMOS tube provides a first bias current to the first NMOS tube. Compared with the prior art, the present invention can achieve fine-tuning of the inductance value by adjusting the first bias voltage.

[0014] The present invention can adjust the current of the first PMOS tube by adjusting the first bias voltage, and this current is also the bias current of the first NMOS tube. The bias current of the first NMOS tube is set to be much larger than the current of the second NMOS tube and the third NMOS tube, and the transconductance of the transistor is proportional to the magnitude of its current, so the transconductance of the first NMOS tube itself is also much larger than the second NMOS tube and the third NMOS tube. Therefore, the change of the transconductance of the first NMOS tube caused by adjusting the first bias voltage is naturally not as drastic as the change of the transconductance of the third NMOS tube caused by the second bias voltage. In addition, because the inductance value is inversely proportional to the transconductance of the first NMOS tube, the second NMOS tube and the third NMOS tube, adjusting the first bias voltage will cause a small change in the inductance value.

[0015] Preferably, the second current source is used to provide a second bias current to the second NMOS transistor.

[0016] Further preferably, the second current source is a second PMOS tube, the drain of the second PMOS tube is connected to the drain of the third NMOS tube, the source of the second PMOS tube is connected to the power supply Vdd, and a second bias voltage is applied to the gate of the second PMOS tube, so that the second PMOS tube provides the first bias current to the second NMOS tube.

[0017] Compared with the prior art, the present invention can achieve a large adjustment of the inductance value by adjusting the second bias voltage. The bias current of the third NMOS tube is set to be much smaller than that of the first NMOS tube, so its own transconductance is also smaller than that of the first NMOS tube. Therefore, adjusting the second bias voltage causes the current of the second PMOS tube and the third NMOS tube to change, which further causes the transconductance of the third NMOS tube to change. This change is relatively drastic relative to the small transconductance value, and ultimately causes the inductance value of the inductor controlled by the transconductance to change drastically.

[0018] Preferably, by regulating one or more of a bias voltage applied to the first current source, a bias voltage applied to the second current source, and a resistance value of a resistor, the inductance value of the active inductor is made to be 0.45 nH-10 nHz.

[0019] Compared with the prior art, the active inductor provided by the present invention can achieve a minimum inductance of about 0.45nH and a maximum inductance of 10nH even if the transistor parameters are fixed by only adjusting the bias voltage and the resistance value.

[0020] Further preferably, the area of ​​the active inductor is 500-800 square micrometers.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The present invention replaces the passive inductor in the BAW radio frequency filter with an active inductor. The insertion loss of the S21 curve of the BAW filter before and after the replacement is not much different in the passband. The BAW filter with the active inductor has better out-of-band suppression near both ends of the passband. Therefore, the active inductor provided by the present invention can be used to replace the inductor in the BAW filter, thereby solving the problem that the BAW filter is too large and difficult to integrate, and the problem that the inductance value is difficult to adjust. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the original bulk acoustic wave filter; Figure 2 A schematic diagram of the structure of a bulk acoustic wave filter provided in a specific embodiment of the present invention; Figure 3 A comparison diagram of S curves of an original BAW filter and a BAW filter provided by a specific embodiment of the present invention; Figure 4 A schematic diagram of the basic principle of an active inductor provided in a specific embodiment of the present invention; Figure 5 A schematic diagram of an active inductor structure provided for a specific embodiment of the present invention; Figure 6 A simulation curve diagram of an active inductor provided by a specific embodiment of the present invention; Figure 7 A Q value curve diagram of an active inductor provided in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings.

[0024] The present invention is described in detail below in conjunction with specific embodiments and drawings. For the convenience of description, the structures shown in the drawings are only relevant parts of the present invention, rather than all structures. For the convenience of description and understanding, some typical embodiments are provided below, and the present invention includes but is not limited to the listed embodiments.

[0025] The original bulk acoustic wave filter provided in the prior art is as follows Figure 1As shown, it includes a series trunk and multiple parallel branches, wherein the parallel branches are connected between the series trunk and the ground line. The series trunk includes four series BAW resonators connected in series in sequence, namely X11, X12, X21 and X23.

[0026] The parallel branches of the original BAW filter are separated by a series BAW resonator, and each parallel branch includes a parallel BAW resonator and a passive inductor connected in series in sequence, and the passive inductor is grounded. The parallel BAW resonators are X19, X20, X22 and X24, and the passive inductors connected in series with the parallel BAW resonators are L10, L11, L12 and L13 respectively.

[0027] The series BAW resonator and the parallel BAW resonator of the original BAW filter are both FBAR resonators, made of AlN with a thickness of 20nm; the inductances of the passive inductors L10, L11, L12 and L13 are 1.6nH, 1.2nH, 950pH and 15nH respectively. The two ports of the BAW filter are connected to Term1 and Term2 respectively, wherein Term1 and Term2 are ports for measuring the S parameters of the filter, Num is the port number, and Z is the source impedance of Term1 and the load impedance of Term2.

[0028] The active inductor provided by the specific embodiment of the present invention replaces the passive inductor of the original BAW filter to form a heterogeneous integrated BAW BAW RF filter. The specific implementation method of the present invention first draws the schematic diagram of the active inductor for testing. After the test is successful, the voltage required by the transistor is biased with an external power supply, and then it is connected to the BAW resonator to perform a joint simulation of the BAW filter, and then the layout is made and the wafer is tested. Figure 2 As shown, the heterogeneous integrated BAW bulk acoustic wave RF filter with embedded active inductor provided in the specific embodiment of the present invention is to replace the corresponding passive inductors L10-L13 with the active inductors SNP1-SNP5 provided in the specific embodiment of the present invention respectively, and then perform S parameter simulation on the filter. Figure 3 This is the S21 curve of the filter before and after inductor replacement.

[0029] exist Figure 3 In the figure, the red line is the S21 transmission curve of the original BAW filter using passive inductors, and the blue line is the S21 transmission curve of the BAW filter after using active inductors. It can be seen that the insertion loss of the two in the passband is the same, and the BAW filter with active inductors has better out-of-band suppression near both ends of the passband.

[0030] The specific embodiment of the present invention provides a schematic diagram of an active inductor for replacing a passive inductor. Figure 4As shown, it includes a first transconductance amplifier, a second transconductance amplifier and a capacitor. The input end of the active inductor is connected to the positive input end of the first transconductance amplifier, and the negative input end of the first transconductance amplifier is grounded. The voltage signal V2 is converted into a current signal G1V2 through the first transconductance amplifier, wherein G1 is the transconductance of the first transconductance amplifier.

[0031] The output end of the first transconductance amplifier provided in a specific embodiment of the present invention is respectively connected to one end of the capacitor and the negative electrode of the input end of the second transconductance amplifier, the positive electrode of the input end of the second transconductance amplifier is grounded, and the other end of the capacitor is grounded. The current signal G1V2 forms a voltage signal V1 under the action of the capacitor, and the voltage signal V1 is input into the second transconductance amplifier, and the voltage signal V1 is converted into a current signal G2V1 through the second transconductance amplifier, where G2 is the transconductance of the second transconductance amplifier.

[0032] The output end of the second transconductance amplifier provided in the specific embodiment of the present invention is connected to the output end of the active inductor. The input end and the output end provided in the specific embodiment of the present invention have the same endpoints. In the circuit provided in the specific embodiment of the present invention, the input end and the output end of the active inductor are both endpoints (1). When the component parameters remain unchanged, the current signal G2V1 is proportional to I in The capacitance impedance provided by the specific embodiment of the present invention varies with the frequency, so that the voltage across the second transconductance amplifier is affected by the frequency, thereby affecting the input voltage of the second transconductance amplifier, and then affecting the current at the output end. According to the circuit analysis, it can be known that the input voltage and current relationship of the component is Z in =sC / (G1*G2)≡ sL , s=jω, where j is the coefficient, ω is the angular frequency, L is the inductance, and C is the capacitance. The component simulates an inductor.

[0033] The specific embodiment of the present invention is based on Figure 4 The principle of the invention provides a structure of an active inductor, wherein the transconductance amplifier of the active inductor is formed by CMOS transistors, specifically, as Figure 5 As shown, two PMOS tubes, three NMOS tubes and a resistor R1 are structured, wherein the first NMOS tube M1 is used as a positive transconductance amplifier, the second NMOS tube M2 and the third NMOS tube M3 are used as negative transconductance amplifiers, and the first PMOS tube and the second PMOS tube provide bias current to the first NMOS tube and the second NMOS tube respectively.

[0034] The gate of the first NMOS tube M1 provided in the specific embodiment of the present invention is connected to the drain M3 of the third NMOS tube, the source of the first NMOS tube M1 is grounded, the drain of the first NMOS tube M1 is respectively connected to the input end of the active inductor and the drain of the first PMOS tube M4, and the first bias voltage V is applied to the gate of the first PMOS tube M4.bias1 The first PMOS transistor M4 provides the first bias current I1 to the first NMOS transistor M1, and the first bias voltage V bias1 The bias current input to the first NMOS tube M1 is adjusted, so that the inductance of the active inductor can be conveniently and efficiently fine-tuned. Therefore, the input current I input to the first NMOS tube M1 is in is the first bias current I1 and the input impedance Z in The corresponding current sum, the first NMOS tube M1 provided in the specific embodiment of the present invention has the function equivalent to Figure 4 The gate of the first NMOS tube M1 provided in the specific embodiment of the present invention is connected to the drain of the third NMOS tube M3, which is equivalent to Figure 1 Connect terminal (2) in the circuit to the negative input terminal of the second transconductance amplifier.

[0035] The second NMOS tube M2 and the third NMOS tube M3 provided in the specific embodiment of the present invention as negative transconductance amplifiers correspond to Figure 4 The first transconductance amplifier in.

[0036] The gate of the second NMOS transistor M2 provided in the specific embodiment of the present invention is connected to the output end of the active inductor, the source of the second NMOS transistor M2 is grounded, and the drain of the second NMOS transistor M2 is respectively connected to the gate of the third NMOS transistor M3 and one end of the resistor R1.

[0037] The drain of the third NMOS transistor M3 provided in the specific embodiment of the present invention is also connected to the drain of the second PMOS transistor M5, and the second bias voltage V is applied to the gate of the second PMOS transistor M5. bias2 The second PMOS tube M5 provides the second bias current I2 to the third NMOS tube M3, and the source of the third NMOS tube M3 is grounded. The specific embodiment of the present invention can adjust the second bias voltage V bias2 The inductance value of the active inductor can be adjusted to a greater extent.

[0038] The specific embodiment of the present invention mainly realizes the internal capacitance of the first NMOS tube M1. Figure 4 The role of capacitor C is shown.

[0039] The source of the first PMOS tube M4, the source of the second PMOS tube M5 and the other end of the resistor R1 provided in the specific embodiment of the present invention are respectively connected to the power supply VDD. The specific embodiment of the present invention adjusts the resistance value of the resistor R1 to control the second NMOS tube so as to adjust the transconductance G1 of the corresponding first transconductance variable resistor, thereby fine-tuning the inductance value of the active inductor provided in the specific embodiment of the present invention.

[0040] The resistor R1 provided in the specific embodiment of the present invention is a necessary component. If it is removed, the drain of the M2 tube is directly connected to the power supply vdd, so that the M2 tube cannot achieve the signal amplification function, and the M3 tube whose gate is connected to the drain of the M2 tube cannot achieve the signal amplification function. Finally, the M1 tube whose gate is connected to the drain of the M3 tube cannot control the current according to the input signal Vin, so the active inductor cannot work normally.

[0041] The active inductor provided in the specific embodiment of the present invention can realize the basic function of an inductor. The real part (Z(1,1)) and imaginary part (Z(1,1)) of the impedance of the active inductor vary with frequency as follows: Figure 6 As shown, even if the transistor parameters are fixed, only relying on Figure 2 V bias1 , V bias2 and R1, the inductance can still be as low as 0.45nH and as high as 10nH. bias2 Ability to adjust the inductance value, V bias1 R1 and R2 can fine-tune the inductance, and R1 also helps to adjust the Q value. Therefore, the active inductor provided in the specific embodiment of the present invention is an active inductor with a large bandwidth, high Q value and wide tuning range, and its inductance and Q value are adjustable.

[0042] The active inductor provided in the specific embodiment of the present invention can be combined with a bulk acoustic wave (BAW) device to form a filter working in a high-end. The characteristic is that it can achieve the filtering performance of an ordinary BAW filter, and can greatly reduce the area of ​​the filter, making it easy to integrate, and can also adjust the parameters of the filter by adjusting the active inductor.

[0043] like Figure 7 As shown in the figure, by adjusting vbias1 and vbias2, the active inductor can achieve the highest Q value m3 of 6000 at 4GHz, 7GHz, and 9GHz respectively under similar inductance values, which is significantly higher than the Q value of the passive inductor.

[0044] In one embodiment, the area of ​​the active inductor provided in this embodiment is 15um×40um, which is much smaller than the area of ​​the passive inductor. The area of ​​the passive inductor in the prior art is 20,000 square microns to 180,000 square microns.

Claims

1. A heterogeneous integrated BAW bulk acoustic wave radio frequency filter with embedded active inductor, characterized in that: It includes a series trunk and a plurality of parallel branches, wherein the parallel branches are connected between the series trunk and a ground line; The series trunk circuit includes a plurality of series bulk acoustic wave resonators connected in series in sequence; There is at least one series BAW resonator between the parallel branches, and the parallel branches include a series-connected parallel BAW resonator and an inductor, wherein the inductor on at least one parallel branch or the series branch is an active inductor.

2. The heterogeneous integrated BAW bulk acoustic wave radio frequency filter with embedded active inductor according to claim 1, characterized in that: The active inductor device comprises: a first NMOS transistor, wherein the gate of the first NMOS transistor is connected to the drain of the third NMOS transistor, the source of the first NMOS transistor is grounded, and the drain of the first NMOS transistor is respectively connected to the input end of the active inductor and the drain of the first current source; a second NMOS transistor, wherein the gate of the second NMOS transistor is connected to the output end of the active inductor, the source of the second NMOS transistor is grounded, and the drain of the second NMOS transistor is respectively connected to the gate of the third NMOS transistor and one end of the resistor; a third NMOS tube, wherein the drain of the third NMOS tube is also connected to the drain of the second current source, and the source of the third NMOS tube is grounded; The source of the first current source, the source of the second current source and the other end of the resistor are respectively connected to a power source VDD.

3. The heterogeneous integrated BAW bulk acoustic wave radio frequency filter with embedded active inductor according to claim 2, characterized in that: The first current source is used to provide a first bias current to the first NMOS transistor.

4. The heterogeneous integrated BAW bulk acoustic wave radio frequency filter with embedded active inductor according to claim 2, characterized in that: The first current source is a first PMOS tube, the drain of the first PMOS tube is connected to the drain of the first NMOS tube, the source of the first PMOS tube is connected to the power supply Vdd, and a first bias voltage is applied to the gate of the first PMOS tube, so that the first PMOS tube provides a first bias current to the first NMOS tube.

5. The heterogeneous integrated BAW bulk acoustic wave radio frequency filter with embedded active inductor according to claim 2, characterized in that: The second current source is used to provide a second bias current to the second NMOS transistor.

6. The heterogeneous integrated BAW bulk acoustic wave radio frequency filter with embedded active inductor according to claim 5, characterized in that: The second current source is a second PMOS tube, the drain of the second PMOS tube is connected to the drain of the third NMOS tube, the source of the second PMOS tube is connected to the power supply Vdd, and a second bias voltage is applied to the gate of the second PMOS tube, so that the second PMOS tube provides a first bias current to the second NMOS tube.

7. The heterogeneous integrated BAW bulk acoustic wave radio frequency filter with embedded active inductor according to claim 2, characterized in that: By regulating one or more of the first bias voltage applied to the first current source, the bias voltage applied to the second current source, and the resistance value of the resistor, the inductance value of the active inductor is set to 0.45 nH-10 nHz.

8. The heterogeneous integrated BAW bulk acoustic wave radio frequency filter with embedded active inductor according to claim 7, characterized in that: The area of ​​the active inductor is 500-800 square micrometers.

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