CN111200412B - Low-pass filter capacitance compensation circuit and method based on ring oscillator - Google Patents
Low-pass filter capacitance compensation circuit and method based on ring oscillator Download PDFInfo
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- CN111200412B CN111200412B CN201811367262.6A CN201811367262A CN111200412B CN 111200412 B CN111200412 B CN 111200412B CN 201811367262 A CN201811367262 A CN 201811367262A CN 111200412 B CN111200412 B CN 111200412B
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/01—Frequency selective two-port networks
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
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Abstract
The application discloses a low-pass filter capacitance compensation circuit based on a ring oscillator, which comprises a fourth-order low-pass filter, a first inverter, a second inverter, a third inverter, a fourth inverter and a capacitance control adjustment circuit, wherein the output end of the fourth-order low-pass filter is connected with the input end of the second inverter through the first inverter, the output end of the fourth inverter is connected with the input end of the capacitance control adjustment circuit, and the output end of the capacitance control adjustment circuit is connected with the second input end of the fourth-order low-pass filter. The first inverter, the second inverter, the third inverter and the fourth-order low-pass filter form the oscillation loop, so that delay can be effectively reduced, capacitance of the fourth-order low-pass filter can be more accurately compensated, and the circuit design structure is simple, and power consumption can be effectively reduced. The application can be widely applied to the field of electronic circuits.
Description
Technical Field
The application relates to the technical field of electronic circuits, in particular to a low-pass filter capacitance compensation circuit and method based on a ring oscillator.
Background
The filter is an important module in an analog integrated circuit, and the precise bandwidth is certainly the most important design index of the filter. However, the capacitor used in the filter may deviate from the design value due to the influence of manufacturing process, temperature, etc., and the bandwidth of the filter may be erroneous, so that the capacitor of the filter needs to be compensated.
Filters are commonly used circuit elements. To compensate for the capacitance used by the filter, a comparator and a buffer are typically used to implement the oscillation along with a fourth order low pass filter, and then the waveform generated by the oscillation is frequency detected to compensate for the capacitance. However, although the circuit can realize the purpose of capacitance compensation, the comparator has certain delay, and the oscillation frequency can not well follow the bandwidth of the fourth-order low-pass filter, so that certain error is generated in the frequency obtained by detection.
Disclosure of Invention
In order to solve the above technical problems, an objective of the present application is to provide a low-pass filter capacitance compensation circuit and method based on a ring oscillator, which can reduce delay.
The technical scheme adopted by the application is as follows:
the utility model provides a low pass filter capacitance compensation circuit based on ring oscillator, includes fourth order low pass filter, first phase inverter, second phase inverter, third phase inverter, fourth phase inverter and capacitance control adjustment circuit, the output of fourth order low pass filter passes through first phase inverter and then is connected with the input of second phase inverter, the output of second phase inverter is connected with the input of third phase inverter and the input of fourth phase inverter respectively, the output of third phase inverter is connected with the first input of fourth order low pass filter, the output of fourth phase inverter is connected with the input of capacitance control adjustment circuit, the output of capacitance control adjustment circuit is connected with the second input of fourth order low pass filter.
As a further improvement of the low-pass filter capacitance compensation circuit based on the ring oscillator, the capacitance control adjustment circuit comprises a pulse calculator and an arithmetic comparator, wherein the output end of the fourth inverter is connected with the input end of the pulse calculator, the output end of the pulse calculator is connected with the input end of the arithmetic comparator, and the output end of the arithmetic comparator is connected with the second input end of the fourth-order low-pass filter.
As a further improvement of the low-pass filter capacitance compensation circuit based on the ring oscillator, the fourth-order low-pass filter is composed of two biquad low-pass filters.
The other technical scheme adopted by the application is as follows:
a compensation method for the ring oscillator-based low pass filter capacitance compensation circuit, comprising the steps of:
A. adjusting an oscillation waveform generated by the fourth-order low-pass filter through the first inverter, the second inverter and the third inverter;
B. pulse counting is carried out on the oscillating waveform through a pulse calculator, so that a pulse count value is obtained;
C. comparing the pulse count value with a preset maximum threshold value and a preset minimum threshold value, if the pulse count value is smaller than the minimum threshold value or the pulse count value is larger than the maximum threshold value, adjusting the capacitance in the fourth-order low-pass filter through a capacitance control adjusting circuit, and returning to the execution step A; otherwise, the oscillating circuit formed by the first inverter, the second inverter, the third inverter and the fourth-order low-pass filter is disconnected.
The beneficial effects of the application are as follows:
according to the low-pass filter capacitance compensation circuit and method based on the ring oscillator, the first inverter, the second inverter, the third inverter and the fourth-order low-pass filter form the oscillation loop, so that delay time can be effectively reduced, square wave frequency of an oscillation frequency monitoring point can well follow the bandwidth of the fourth-order low-pass filter, capacitance of the fourth-order low-pass filter can be more accurately compensated, and the circuit design structure is simple, and power consumption can be effectively reduced.
Drawings
FIG. 1 is a schematic diagram of a low pass filter capacitance compensation circuit based on a ring oscillator according to the present application;
FIG. 2 is a flow chart of the steps of the compensation method of the present application.
Detailed Description
The following is a further description of embodiments of the application, taken in conjunction with the accompanying drawings:
referring to fig. 1, the low-pass filter capacitance compensation circuit based on a ring oscillator of the present application includes a fourth-order low-pass filter, a first inverter I1, a second inverter I2, a third inverter I3, a fourth inverter I4, and a capacitance control adjustment circuit, wherein an output end of the fourth-order low-pass filter is connected to an input end of the second inverter I2 through the first inverter I1, an output end of the second inverter I2 is connected to an input end of the third inverter I3 and an input end of the fourth inverter I4, an output end of the third inverter I3 is connected to a first input end of the fourth-order low-pass filter, an output end of the fourth inverter I4 is connected to an input end of the capacitance control adjustment circuit, and an output end of the capacitance control adjustment circuit is connected to a second input end of the fourth-order low-pass filter.
In the application, the first inverter I1, the second inverter I2, the third inverter I3 and the fourth-order low-pass filter form a ring oscillator, so that the circuit is simple and the time delay is low; and the single-ended input and output of the fourth-order low-pass filter is used instead of the differential input and output, so that the area of the oscillator is smaller, and the power consumption is lower.
In this embodiment, the cut-off frequency f of the fourth-order low-pass filter c ＝1/2πR eq C, characteristic frequency of the inverter is f T . Because f T >>f c So the oscillation frequency f of the oscillator osc ≈f c The oscillation frequency closely follows the bandwidth of the fourth-order low-pass filter, so that the capacitance adjustment control circuit can more accurately adjust the capacitance C of the filter, the characteristic frequency of the inverter is far greater than the cut-off frequency of the fourth-order low-pass filter, and the delay of the inverter is extremely small.
Further as a preferred embodiment, the capacitance control adjustment circuit includes a pulse calculator and an arithmetic comparator, the output end of the fourth inverter I4 is connected to the input end of the pulse calculator, the output end of the pulse calculator is connected to the input end of the arithmetic comparator, and the output end of the arithmetic comparator is connected to the second input end of the fourth-order low-pass filter.
Further as a preferred embodiment, the fourth-order low-pass filter is composed of two biquad low-pass filters.
Referring to fig. 2, the compensation method of the embodiment of the application specifically includes the following steps:
s1, when the four-order low-pass filter starts to work, single-end input and output of the four-order low-pass filter are connected into an oscillation loop, input and output of the other end of the four-order low-pass filter are suspended, and then oscillation waveforms generated by the four-order low-pass filter are adjusted through a first inverter I1, a second inverter I2 and a third inverter I3;
s2, counting the pulse of the oscillation waveform by a pulse calculator to obtain a pulse count value;
s3, comparing the pulse count value with a preset maximum threshold value Nmax and a preset minimum threshold value Nmin, if the pulse count value is smaller than the minimum threshold value Nmin or the pulse count value is larger than the maximum threshold value Nmax, adjusting the capacitance in the fourth-order low-pass filter through a capacitance control adjusting circuit, and returning to the step S1; otherwise, the oscillating circuit formed by the first inverter I1, the second inverter I2, the third inverter I3 and the fourth-order low-pass filter is disconnected.
From the above, the first inverter I1, the second inverter I2, the third inverter I3 and the fourth-order low-pass filter form the oscillation loop, so that the delay time can be effectively reduced, the square wave frequency of the oscillation frequency monitoring point can well follow the bandwidth of the fourth-order low-pass filter, the capacitance of the fourth-order low-pass filter can be more accurately compensated, and the circuit design structure is simple, so that the power consumption can be effectively reduced.
While the preferred embodiment of the present application has been described in detail, the application is not limited to the embodiment, and various equivalent modifications and substitutions can be made by those skilled in the art without departing from the spirit of the application, and these equivalent modifications and substitutions are intended to be included in the scope of the present application as defined in the appended claims.
Claims (2)
1. The low-pass filter capacitance compensation circuit based on the ring oscillator is characterized by comprising a fourth-order low-pass filter, a first inverter, a second inverter, a third inverter, a fourth inverter and a capacitance control adjustment circuit, wherein the output end of the fourth-order low-pass filter is connected with the input end of the second inverter through the first inverter, the output end of the second inverter is respectively connected with the input end of the third inverter and the input end of the fourth inverter, the output end of the third inverter is connected with the first input end of the fourth-order low-pass filter, the output end of the fourth inverter is connected with the input end of the capacitance control adjustment circuit, and the output end of the capacitance control adjustment circuit is connected with the second input end of the fourth-order low-pass filter;
the capacitor control adjusting circuit comprises a pulse calculator and an arithmetic comparator, wherein the output end of the fourth inverter is connected with the input end of the pulse calculator, the output end of the pulse calculator is connected with the input end of the arithmetic comparator, and the output end of the arithmetic comparator is connected with the second input end of the fourth-order low-pass filter;
the compensation method of the capacitance compensation circuit comprises the following steps:
A. adjusting an oscillation waveform generated by the fourth-order low-pass filter through the first inverter, the second inverter and the third inverter;
B. pulse counting is carried out on the oscillating waveform through a pulse calculator, so that a pulse count value is obtained;
C. comparing the pulse count value with a preset maximum threshold value and a preset minimum threshold value, if the pulse count value is smaller than the minimum threshold value or the pulse count value is larger than the maximum threshold value, adjusting the capacitance in the fourth-order low-pass filter through a capacitance control adjusting circuit, and returning to the execution step A; otherwise, the oscillating circuit formed by the first inverter, the second inverter, the third inverter and the fourth-order low-pass filter is disconnected.
2. A low pass filter capacitance compensation circuit based on a ring oscillator as claimed in claim 1, wherein: the fourth-order low-pass filter is composed of two biquad low-pass filters.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811367262.6A CN111200412B (en) | 2018-11-16 | 2018-11-16 | Low-pass filter capacitance compensation circuit and method based on ring oscillator |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811367262.6A CN111200412B (en) | 2018-11-16 | 2018-11-16 | Low-pass filter capacitance compensation circuit and method based on ring oscillator |
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| CN111200412A CN111200412A (en) | 2020-05-26 |
| CN111200412B true CN111200412B (en) | 2023-08-25 |
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| US5175452A (en) * | 1991-09-30 | 1992-12-29 | Data Delay Devices, Inc. | Programmable compensated digital delay circuit |
| US5420547A (en) * | 1993-06-30 | 1995-05-30 | Sony Corporation | Ring oscillator having bandpass filters between stages |
| JP2002271173A (en) * | 2001-03-13 | 2002-09-20 | Fujitsu Ltd | Filter circuit, semiconductor device, filter system and method for controlling signal frequency |
| WO2004010583A1 (en) * | 2002-07-19 | 2004-01-29 | Sun Microsystems, Inc. | Loop filter capacitor leakage current control |
| CN105048996A (en) * | 2015-06-03 | 2015-11-11 | 西安电子科技大学 | Mode-mixing low-pass filter with cut-off frequency self-correction |
| CN107681994A (en) * | 2017-09-23 | 2018-02-09 | 深圳大学 | A kind of pierce circuit |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6963232B2 (en) * | 2003-08-11 | 2005-11-08 | Rambus, Inc. | Compensator for leakage through loop filter capacitors in phase-locked loops |
| US7659783B2 (en) * | 2007-07-16 | 2010-02-09 | Micrel, Inc. | System and method for phase-locked loop (PLL) for high-speed memory interface (HSMI) |
| US8299826B2 (en) * | 2009-08-25 | 2012-10-30 | Sitime Corporation | Phase locked loop circuitry having switched resistor loop filter circuitry, and methods of operating same |
| US9219486B2 (en) * | 2013-11-18 | 2015-12-22 | California Institute Of Technology | Quadrature-based injection locking of ring oscillators |
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2018
- 2018-11-16 CN CN201811367262.6A patent/CN111200412B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5175452A (en) * | 1991-09-30 | 1992-12-29 | Data Delay Devices, Inc. | Programmable compensated digital delay circuit |
| US5420547A (en) * | 1993-06-30 | 1995-05-30 | Sony Corporation | Ring oscillator having bandpass filters between stages |
| JP2002271173A (en) * | 2001-03-13 | 2002-09-20 | Fujitsu Ltd | Filter circuit, semiconductor device, filter system and method for controlling signal frequency |
| WO2004010583A1 (en) * | 2002-07-19 | 2004-01-29 | Sun Microsystems, Inc. | Loop filter capacitor leakage current control |
| CN105048996A (en) * | 2015-06-03 | 2015-11-11 | 西安电子科技大学 | Mode-mixing low-pass filter with cut-off frequency self-correction |
| CN107681994A (en) * | 2017-09-23 | 2018-02-09 | 深圳大学 | A kind of pierce circuit |
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