CN114157240A - Oscillator circuit - Google Patents
Oscillator circuit Download PDFInfo
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- CN114157240A CN114157240A CN202111301614.XA CN202111301614A CN114157240A CN 114157240 A CN114157240 A CN 114157240A CN 202111301614 A CN202111301614 A CN 202111301614A CN 114157240 A CN114157240 A CN 114157240A
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- 239000003990 capacitor Substances 0.000 claims abstract description 59
- 230000008859 change Effects 0.000 abstract description 5
- 230000033228 biological regulation Effects 0.000 abstract description 4
- 238000000034 method Methods 0.000 description 5
- 230000007423 decrease Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000003071 parasitic effect Effects 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
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- 238000006467 substitution reaction Methods 0.000 description 1
- 238000009966 trimming Methods 0.000 description 1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
- H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator
- H03B5/36—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device
- H03B5/364—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator active element in amplifier being semiconductor device the amplifier comprising field effect transistors
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
- H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
- H03B5/02—Details
- H03B5/04—Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
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- Inductance-Capacitance Distribution Constants And Capacitance-Resistance Oscillators (AREA)
Abstract
The invention provides an oscillator circuit, which comprises a voltage-controlled oscillator, an operational amplifier and a switched capacitor; the power supply voltage is connected to the non-inverting input end of the operational amplifier after being divided, the power supply voltage is connected with the switch capacitor after being divided, the common end of the switch capacitor is connected with the inverting input end of the operational amplifier, the output end of the operational amplifier is connected with the input end of the voltage-controlled oscillator, the output of the voltage-controlled oscillator is used as the output of the oscillator circuit, and meanwhile, the control end of the switch capacitor is connected to change the equivalent impedance of the switch capacitor, so that a frequency-voltage negative feedback loop is formed, and the voltages of the non-inverting input end and the inverting input end of the operational amplifier are kept consistent. The invention has the characteristics of independence on power supply voltage, independence on temperature, extremely small deviation between chips and the like, can simply realize frequency regulation, has wide frequency regulation range, is convenient to apply in a system, and has high reliability.
Description
Technical Field
The present disclosure relates to the field of integrated circuit technology, and more particularly, to an oscillator circuit.
Background
Oscillator circuits are common modular circuits in integrated circuits. The conventional oscillator technology has many disadvantages, such as large frequency variation with power supply voltage, large temperature variation, large frequency deviation, etc. These problems may cause difficulty in designing the system, and even cause the system to fail to work properly.
A conventional ring oscillator is shown in fig. 1. The illustration includes three stages, and two transistors in each vertical direction constitute one stage. Each stage consists of a lower NMOS and an upper PMOS, which form an inverter. The three-stage inverters are connected end to form a ring, so that the ring oscillator is formed. However, the oscillator frequency of this structure varies strongly with supply voltage and temperature, and is very sensitive to internal node parasitic capacitance. In high frequency applications, the oscillator transistor size can only be made small in order to achieve high oscillation frequencies, which results in large chip-to-chip deviations. Generally, the ring oscillator has a simple structure and is convenient to implement, but has large frequency deviation and great defects.
Fig. 2 shows a Current-mode ring oscillator (VCO), referred to as a Current started VCO. In the ring oscillator of fig. 1, each inverter is connected in series with a current source. The current source can play a role in limiting current, so that the time delay of each stage of inverter is more controllable, and the frequency of the oscillator is more controllable. There are many techniques to counteract the temperature characteristic of the frequency by giving the current source a specific temperature coefficient. Although the oscillator of fig. 2 provides some improvement over that of fig. 1, it still does not solve the problem at all, or meet the requirements of sophisticated system applications.
Disclosure of Invention
In view of this, the embodiments of the present disclosure provide an oscillator circuit, which is a novel high-precision oscillator, and has the characteristics of independence on power supply voltage, independence on temperature, extremely small deviation between chips, and the like, and can realize frequency adjustment very simply, and the frequency adjustment range is wide, and is convenient to apply in a system, and has high reliability.
In order to achieve the above purpose, the invention provides the following technical scheme:
an oscillator circuit comprising a frequency-voltage negative feedback loop comprising a voltage controlled oscillator, an operational amplifier and a switched capacitor;
the power supply voltage is connected to the in-phase input end of the operational amplifier after voltage division, the power supply voltage is connected with the switch capacitor after voltage division, the public end of the switch capacitor is connected with the reverse phase input end of the operational amplifier, the output end of the operational amplifier is connected with the input end of the voltage-controlled oscillator, the output of the voltage-controlled oscillator is used as the output of the oscillator circuit, and the control end of the switch capacitor is connected at the same time and used for changing the equivalent impedance of the switch capacitor, so that the frequency-voltage negative feedback loop is formed, and the voltages of the in-phase input end and the reverse phase input end of the operational amplifier are kept consistent.
Furthermore, the frequency-voltage negative feedback loop further comprises a first resistor and a second resistor, one end of the first resistor is connected with the power supply, the other end of the first resistor is connected with one end of the second resistor, the other end of the second resistor is grounded, and the common end of the first resistor and the second resistor is connected with the in-phase input end of the operational amplifier and is used for dividing the power supply voltage and then connecting the divided power supply voltage to the in-phase input end of the operational amplifier.
Furthermore, the frequency-voltage negative feedback loop further comprises a third resistor, one end of the third resistor is connected with the power supply, and the other end of the third resistor is connected with the switch capacitor.
Further, the switched capacitor includes a first switch, a second switch and a capacitor, one end of the first switch is a positive end of the switched capacitor, the first switch is connected to the third resistor, the other end of the first switch is connected to one end of the second switch and one end of the capacitor, and the other end of the second switch and the other end of the capacitor are negative ends of the switched capacitor and are respectively connected to the ground.
Further, the control signals of the first switch and the second switch are non-overlapping clock signals.
Further, the operational amplifier comprises a first NMOS transistor, a second NMOS transistor, a first PMOS transistor, a second PMOS transistor, and a current source, wherein a gate of the first NMOS transistor is a non-inverting input terminal of the operational amplifier, a gate of the second NMOS transistor is an inverting input terminal of the operational amplifier, sources of the first NMOS transistor and the second NMOS transistor are connected to one end of the current source, the other end of the current source is grounded, a drain of the first NMOS transistor is connected to the gate and the drain of the first PMOS transistor and the gate of the second PMOS transistor, the sources of the first PMOS transistor and the second PMOS transistor are connected to a power source, and drains of the second NMOS transistor and the second PMOS transistor are output terminals of the operational amplifier.
Furthermore, the voltage-controlled oscillator is formed by connecting a plurality of MOS tubes, the output end of the voltage-controlled oscillator is the output end of the oscillator circuit, and the signal is fed back to the control end of the switch capacitor to form closed-loop control.
Further, the resistance values of the first resistor and the second resistor are equal.
Further, the third resistor is a thin film resistor with zero temperature coefficient.
Further, the capacitor is a gate capacitor.
Compared with the traditional oscillator implementation method, the oscillator circuit has the advantages that:
(1) the frequency does not change (independent of the supply voltage) with supply voltage variations.
(2) The frequency does not change with temperature (independent of temperature).
(3) The frequency is accurate, and the deviation between the chips is extremely small (can reach less than 1 per thousand).
(4) The frequency adjustment can be realized simply, and the adjustable range is wide (up to +/-100 percent).
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present disclosure, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a conventional ring oscillator circuit;
FIG. 2 is a conventional current mode ring oscillator circuit;
FIG. 3 is a schematic diagram of an oscillator circuit according to the present invention;
fig. 4 is a detailed structure diagram of the oscillator circuit according to the present invention.
Detailed Description
The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.
The embodiments of the present disclosure are described below with specific examples, and other advantages and effects of the present disclosure will be readily apparent to those skilled in the art from the disclosure in the specification. It is to be understood that the described embodiments are merely illustrative of some, and not restrictive, of the embodiments of the disclosure. The disclosure may be embodied or carried out in various other specific embodiments, and various modifications and changes may be made in the details within the description without departing from the spirit of the disclosure. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.
It is noted that various aspects of the embodiments are described below within the scope of the appended claims. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is merely illustrative. Based on the disclosure, one skilled in the art should appreciate that one aspect described herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method practiced using any number of the aspects set forth herein. Additionally, such an apparatus may be implemented and/or such a method may be practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.
It should be noted that the drawings provided in the following embodiments are only for illustrating the basic idea of the present disclosure, and the drawings only show the components related to the present disclosure rather than the number, shape and size of the components in actual implementation, and the type, number and ratio of the components in actual implementation may be changed arbitrarily, and the layout of the components may be more complicated.
In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects may be practiced without these specific details.
The embodiment of the disclosure provides an oscillator circuit, which introduces frequency-voltage feedback on the basis of a current type ring oscillator, so as to form closed-loop control of a frequency-voltage negative feedback loop, so as to realize accurate frequency which is independent of voltage and temperature and has high consistency.
As shown in fig. 3, according to an embodiment, the oscillator circuit of this embodiment mainly includes a first resistor 1, a second resistor 2, a third resistor 3, a switched capacitor 4, an operational amplifier 5, and a voltage controlled oscillator 6. One end of the first resistor 1 is connected to the power supply 7, and the other end is connected to one end of the second resistor 2. The other end of the second resistor 2 is connected to a reference ground 8. The common terminal of the first resistor 1 and the second resistor 2 is connected to the non-inverting input terminal of the operational amplifier 5. One end of the third resistor 3 is connected to the power supply 7 and the other end is connected to the positive terminal of the switched capacitor 4. The negative terminal of the switched capacitor 4 is connected to a reference ground 8. The common terminal of the third resistor 3 and the switched capacitor 4 is connected to the inverting input terminal of the operational amplifier 5. The output of the operational amplifier 5 is connected to the input of a voltage controlled oscillator 6. The output of the voltage controlled oscillator 6 is connected to the control terminal of the switched capacitor 4 and is also the oscillator output 9.
One specific embodiment is shown in figure 4: the switched capacitor 4 is composed of a first switch S1, a second switch S2 and a capacitor C. One end of the first switch S1 is the positive terminal of the switched capacitor 4, and is connected to one end of the third resistor 3. The other terminal of the first switch S1 is connected to the second switch S2 and the capacitor C. The other end of the second switch S2 and the capacitor C, which is the negative terminal of the switched capacitor 4, is connected to the reference ground 8. The oscillator output 9 is connected to the control terminal (FOUT in the figure) of the switched capacitor 4 for controlling the on and off of the first switch S1 and the second switch S2. The control signals of the first switch S1 and the second switch S2 are non-overlapping clocks.
The operational amplifier 5 comprises a first NMOS transistor M1, a second NMOS transistor M2, a first PMOS transistor M3, a second PMOS transistor M4 and a current source I0And (4) forming. The gate of the first NMOS transistor M1 is the non-inverting input terminal of the operational amplifier 5, and the gate of the second NMOS transistor M2 is the inverting input terminal of the operational amplifier 5. The sources of the first NMOS transistor M1 and the second NMOS transistor M2 are connected to a current source I0To one end of (a). Current source I0Is connected to reference ground 8. The drain of the first NMOS transistor M1 is connected to the gate and drain of the first PMOS transistor M3 and the gate of the second PMOS transistor M4. The sources of the first PMOS transistor M3 and the second PMOS transistor M4 are connected to the power supply 7. The drains of the second NMOS transistor M2 and the second PMOS transistor M4 are the output terminal (VCTRL in the figure) of the operational amplifier 5.
The voltage-controlled oscillator 6 is composed of MOS transistors M5-M20. The input end of the voltage-controlled oscillator 6 is connected to the gates of the MOS transistor M5, the MOS transistor M7, the MOS transistor M11 and the MOS transistor M15. (the specific connection relationship can refer to the figures and the conventional current mode ring oscillator circuit in the prior art, which is not described in detail here). The drains of the MOS transistor M19 and the MOS transistor M20 are the output terminal of the vco 6, and are connected to the oscillator output 9 and the control terminal of the switched capacitor 4.
In this embodiment, as shown in fig. 3, in the embodiment of the present disclosure, on the basis of a simple voltage-controlled oscillator 6, modules such as a switched capacitor 4 and an operational amplifier 5 are added to form a closed-loop negative feedback, so that a more accurate frequency can be obtained. Under the action of feedback, the voltages of the non-inverting input terminal and the inverting input terminal of the operational amplifier 5 are kept consistent. Assuming that the impedance of the switched capacitor 4 is R4, there is formula (1):
the equivalent resistance R4 of the switched capacitor 4 is calculated as follows. As shown in FIG. 4, the switched capacitor 4 is composed of a capacitor C and two switches (a first switch S1 and a second switch S2), wherein the control signals of the first switch S1 and the second switch S2 are notOverlapping clocks Φ and
assuming that the voltages at the two ends of the switched capacitor are V1 and V2, respectively, the average current flowing through the two ends can be written as the change of the charge divided by the time, i.e., C (V1-V2)/T, in one clock cycle, and then the equivalent resistance is the ratio of the voltage difference and the current at the two ends of the switched capacitor, i.e., the equivalent resistance is expressed by the following formula (2):
from equation (2), it can be seen that the impedance of the switched capacitor 4 is only dependent on the clock frequency f and the capacitance C. By substituting this equation (2) into the above equation (1), the oscillator frequency for stabilizing the loop can be obtained as equation (3):
for simplicity of design, if R1 ═ R2, then the oscillator frequency is equation (4):
it can be seen that the frequency of the oscillator is related to the capacitance C only with the third resistor R3. Because the voltages of the non-inverting input end and the inverting input end of the operational amplifier 5 are obtained by voltage division of the power supply 7, the power supply voltage term is eliminated in the expression, and the frequency of the oscillator is independent of the power supply voltage. And because the oscillator frequency is only related to the resistance and the capacitance, and the resistance and the capacitance can use the thin film resistance and the gate capacitance with zero temperature coefficient, the oscillator frequency is independent of the temperature.
In actual large-scale application, due to random errors in the chip manufacturing process, the actual sizes of various devices in a chip have random deviations to a certain extent, so that the performance of the chip changes. For oscillator circuits, this random error appears as a change in the oscillator frequency. For the oscillator without feedback in fig. 1 and 2, the oscillator frequency is closely related to the MOSFET, the current bias and its parasitic RC, and for high frequency applications, the size needs to be small, so the random error is large, resulting in large frequency deviation of the oscillator. The invention adopts a closed-loop regulation structure, the related factors of the MOSFETs are counteracted under the regulation action of feedback, and the final frequency is only related to the resistance and the capacitance. The area of the resistor and the capacitor can be made larger, and the deviation of the resistor and the capacitor is very small, so that the oscillator frequency of the invention has very high consistency between chips.
During the production and manufacturing process of the integrated circuit, the chip is affected by the process corner, and the performance has some deviation, which is reflected on the oscillator as the deviation of the frequency. Unlike the random errors mentioned above, the bias here is global, i.e., all chips of the entire batch are biased in the same direction. To counteract the effects of such offsets, trimming is now often used to adjust somewhere in the circuit. Because the frequency of the oscillator provided by the present invention is determined by the third resistor R3 and the capacitor C, the resistor R3 can be easily adjusted. Furthermore, the first resistor R1 and the second resistor R2 may also be used to adjust the frequency. Therefore, the oscillator can be adjusted simply and has a wide adjustable range.
Next, as shown in FIG. 4, the operational amplifier 5 is composed of a MOS transistor and a current source I0The simple five-tube operational amplifier is formed. The first NMOS transistor M1 and the second NMOS transistor M2 are differential pair transistors, and the first PMOS transistor M3 and the second PMOS transistor M4 are current mirror loads, so that high gain is achieved. The voltage-controlled oscillator 6 is implemented by MOS transistors M5 to M20, where MOS transistors M7 to M18 are current-mode voltage-controlled oscillators shown in fig. 2, MOS transistor M5 and MOS transistor M6 are used to provide a bias, and MOS transistor M19 and MOS transistor M20 are output driver stages. The output of the voltage controlled oscillator 6 is connected to the oscillator output 9 and this signal is fed back to the control terminal of the switched capacitor 4, forming a closed loop control. When the oscillator frequency becomes high, then the equivalent impedance of the switched capacitor 4 decreases and the operational amplifier 5The voltage at the inverting input terminal of the operational amplifier 5 decreases, the voltage at the output VCTRL of the operational amplifier 5 increases, and thus the bias current of the voltage-controlled oscillator 6 decreases, so that the oscillator frequency becomes low, thereby achieving the effect of negatively feeding back and stabilizing the frequency.
Therefore, the invention provides an accurate oscillator circuit, the frequency of which is independent of the power supply voltage and almost independent of the temperature, the deviation between chips is small, and the frequency is simple and adjustable.
The above description is only for the specific embodiments of the present disclosure, but the scope of the present disclosure is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present disclosure should be covered within the scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.
Claims (10)
1. An oscillator circuit comprising a frequency-voltage negative feedback loop comprising a voltage controlled oscillator, an operational amplifier, and a switched capacitor;
the power supply voltage is connected to the non-inverting input end of the operational amplifier after being divided, the power supply voltage is connected with the switch capacitor after being divided, the public end of the switch capacitor is connected with the inverting input end of the operational amplifier, the output end of the operational amplifier is connected with the input end of the voltage-controlled oscillator, the output of the voltage-controlled oscillator is used as the output of the oscillator circuit and is simultaneously connected with the control end of the switch capacitor and used for changing the equivalent impedance of the switch capacitor, so that the frequency-voltage negative feedback loop is formed, and the voltages of the non-inverting input end and the inverting input end of the operational amplifier are kept consistent.
2. The oscillator circuit according to claim 1, wherein the frequency-voltage negative feedback loop further comprises a first resistor and a second resistor, one end of the first resistor is connected to a power supply, the other end of the first resistor is connected to one end of the second resistor, the other end of the second resistor is grounded, and a common terminal of the first resistor and the second resistor is connected to a non-inverting input terminal of the operational amplifier for dividing a power supply voltage and then connecting the divided power supply voltage to the non-inverting input terminal of the operational amplifier.
3. The oscillator circuit according to claim 1 or 2, wherein the frequency-voltage negative feedback loop further comprises a third resistor, one end of the third resistor is connected to a power supply, and the other end of the third resistor is connected to the switched capacitor.
4. The oscillator circuit of claim 3, wherein the switched capacitor comprises a first switch, a second switch and a capacitor, wherein one end of the first switch is a positive terminal of the switched capacitor and is connected to the third resistor, the other end of the first switch is connected to one end of the second switch and one end of the capacitor, and the other end of the second switch and the other end of the capacitor are negative terminals of the switched capacitor and are respectively connected to ground.
5. The oscillator circuit of claim 4, wherein the control signals for the first switch and the second switch are non-overlapping clock signals.
6. The oscillator circuit according to claim 5, wherein the operational amplifier includes a first NMOS transistor, a second NMOS transistor, a first PMOS transistor, a second PMOS transistor, and a current source, a gate of the first NMOS transistor is a non-inverting input terminal of the operational amplifier, a gate of the second NMOS transistor is an inverting input terminal of the operational amplifier, sources of the first NMOS transistor and the second NMOS transistor are connected to one end of the current source, another end of the current source is grounded, a drain of the first NMOS transistor is connected to the gate and drain of the first PMOS transistor and the gate of the second PMOS transistor, sources of the first PMOS transistor and the second PMOS transistor are connected to a power supply, and drains of the second NMOS transistor and the second PMOS transistor are output terminals of the operational amplifier.
7. The oscillator circuit according to claim 6, wherein the voltage-controlled oscillator is formed by connecting a plurality of MOS transistors, and an output terminal is an output terminal of the oscillator circuit, and the signal is fed back to a control terminal of the switched capacitor to form a closed-loop control.
8. The oscillator circuit of claim 2, wherein the first and second resistors are equal in resistance.
9. The oscillator circuit of claim 3, wherein the third resistance is a zero temperature coefficient sheet resistance.
10. The oscillator circuit of claim 4, wherein the capacitance is a gate capacitance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202111301614.XA CN114157240A (en) | 2021-11-04 | 2021-11-04 | Oscillator circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111301614.XA CN114157240A (en) | 2021-11-04 | 2021-11-04 | Oscillator circuit |
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| CN114157240A true CN114157240A (en) | 2022-03-08 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116073823A (en) * | 2023-03-20 | 2023-05-05 | 上海灵动微电子股份有限公司 | Frequency synthesizer based on switch capacitor |
| CN117691969A (en) * | 2023-12-15 | 2024-03-12 | 江苏帝奥微电子股份有限公司 | Ring oscillator circuit with negative feedback and negative feedback adjusting method thereof |
-
2021
- 2021-11-04 CN CN202111301614.XA patent/CN114157240A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116073823A (en) * | 2023-03-20 | 2023-05-05 | 上海灵动微电子股份有限公司 | Frequency synthesizer based on switch capacitor |
| CN117691969A (en) * | 2023-12-15 | 2024-03-12 | 江苏帝奥微电子股份有限公司 | Ring oscillator circuit with negative feedback and negative feedback adjusting method thereof |
| CN117691969B (en) * | 2023-12-15 | 2024-05-31 | 江苏帝奥微电子股份有限公司 | Ring oscillator circuit with negative feedback and negative feedback adjusting method thereof |
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Address after: Room 201, Block C, Building 1, No. 599 Gaojing Road, Qingpu District, Shanghai, 201702 Applicant after: Shanghai chuantu Microelectronics Co.,Ltd. Address before: No.888, Huanhu West 2nd Road, Lingang New District, China (Shanghai) pilot Free Trade Zone, Pudong New Area, Shanghai, 201306 Applicant before: Shanghai chuantu Microelectronics Co.,Ltd. |