RC time constant calibration system based on ADC system

Abstract

The invention discloses an RC time constant calibration system based on an ADC system, and relates to the field of RC time constant calibration. The system comprises a control module, an RC charging circuit and a capacitor network, the RC charging circuit is used for charging the energy storage capacitor to a preset target voltage; the control module is used for controlling on and off of charging of the RC charging circuit and recording calibration time when the energy storage capacitor is charged to a preset target voltage; determining a compensation capacitance value according to a difference value between the calibration time and preset theoretical time; the capacitor network comprises a plurality of capacitor units which are connected in parallel, and the control module is further used for controlling the number of the energy storage capacitor units connected into the capacitor network according to the compensation capacitance value. According to the invention, the technical problem that the RC time constant is easy to deviate and cannot be efficiently and accurately calibrated and corrected in the ADC design in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of RC time constant calibration, and in particular to an RC time constant calibration system based on an ADC system. Background Art

[0002] In ADC design, the RC time constant (τ = R × C) is a key parameter that determines signal sampling, integration, or filtering. However, the inherent limitations of chip manufacturing processes inevitably lead to significant deviations in RC time parameters, including but not limited to manufacturing tolerances, insufficient matching, and temperature and aging effects.

[0003] Traditional methods for adjusting RC parameter deviations typically use laser trimming, which involves adjusting the resistance or capacitance values ​​during wafer testing. However, this requires additional process steps, is costly, and cannot adapt to dynamic changes in chip operation (such as temperature drift). Alternatively, calibration requires reliance on an external high-precision reference source or clock signal, which consumes chip pins and is difficult to integrate into low-power, miniaturized devices. Summary of the Invention

[0004] The present invention provides an RC time constant calibration system based on an ADC system, which can solve the technical problem in the prior art that the RC time constant in ADC design is prone to deviation but cannot be calibrated and corrected efficiently and accurately. The technical solution is as follows:

[0005] In a first aspect, an embodiment of the present invention provides an RC time constant calibration system based on an ADC system, comprising:

[0006] RC charging circuit, used to charge its own energy storage capacitor to a preset target voltage;

[0007] a capacitor network comprising a plurality of capacitor units connected in parallel;

[0008] A control module is used to control the charging on and off of the RC charging circuit, to record the calibration time when the energy storage capacitor is charged to a preset target voltage, to determine the compensation capacitance value based on the difference between the calibration time and the preset theoretical time, and to control the number of capacitor units in the capacitor network connected to the RC charging circuit based on the compensation capacitance value.

[0009] In some embodiments of the present invention, the RC charging circuit includes a single-pole double-control switch, a first resistor, the energy storage capacitor, a second resistor, a third resistor, and a comparator;

[0010] The first contact of the single-pole double-control switch is electrically connected to the control module, and the second contact of the single-pole double-control switch is connected to one end of the first resistor;

[0011] The other end of the first resistor is connected to one end of the energy storage capacitor, and the other end of the energy storage capacitor is grounded;

[0012] One end of the second resistor is connected to the common end of the single-pole double-control switch, and the other end is connected to one end of the third resistor, and the other end of the third resistor is grounded;

[0013] The first input end of the comparator is connected between the first resistor and the energy storage capacitor, the second input end of the comparator is connected between the second resistor and the third resistor, and the output end of the comparator is connected to the control module.

[0014] In some embodiments of the present invention, the second resistor and the third resistor form a voltage divider resistor network to determine a preset target voltage, and the preset target voltage is input to the second input terminal of the comparator.

[0015] In some embodiments of the present invention, the input parameter of the first input terminal of the comparator is the real-time voltage of the energy storage capacitor when it is charged;

[0016] The comparator is used to compare the real-time voltage of the energy storage capacitor when it is charged with a preset target voltage, and transmit the comparison result to the control module through the output terminal;

[0017] The control module includes a start-stop control unit, which is used to control the single-pole double-control switch to disconnect from the second contact when the real-time voltage is equal to the preset target voltage, and stop charging the energy storage capacitor;

[0018] The start-stop control unit is further configured to control the single-pole double-control switch to be continuously connected to the second contact to charge the energy storage capacitor when the real-time voltage is less than a preset target voltage.

[0019] In some embodiments of the present invention, the control module further includes a timing unit,

[0020] The timing unit is used to record the calibration time when the real-time voltage of the energy storage capacitor during charging is equal to the preset target voltage.

[0021] In some embodiments of the present invention, the control module further includes a capacitance calculation unit;

[0022] The capacitance calculation unit is used to determine the compensation capacitance value according to the following formula:

[0023]

[0024] Among them, floor is the rounding function, which means taking the maximum integer value that does not exceed the current number; Uall Compensation capacitance value; T is the preset theoretical time; rc cyc is the calibration time; f is the frequency of the clock used to record the calibration time when the capacitor is charged to the preset target voltage during the capacitor charging process.

[0025] In some embodiments of the present invention, a temperature code decoder is further included;

[0026] The temperature code decoder is communicatively connected between the control module and the capacitor network, and is used to convert the compensation capacitance value into a temperature code;

[0027] The control module is further configured to determine the number of energy storage capacitor units connected to the capacitor network according to the number of digits of the temperature code.

[0028] In some embodiments of the present invention, the control module further includes a configuration unit;

[0029] The configuration unit is used to determine the interval range of the real-time calibration time according to the preset theoretical time, and configure the clock counting period for recording the calibration time when the energy storage capacitor is charged to the preset target voltage according to the interval range of the real-time calibration time.

[0030] In some embodiments of the present invention, the configuration unit is further configured to configure the number of calibration times for obtaining the energy storage capacitor when charging to a preset target voltage.

[0031] In some embodiments of the present invention, the configuration module further includes a calibration time calculation unit;

[0032] The calibration time calculation unit is further configured to perform an average calculation based on the obtained number of calibration times when the energy storage capacitor is charged to a preset target voltage to obtain a target calibration time.

[0033] The beneficial effects brought about by the technical solutions provided by some embodiments of the present invention include at least: controlling the charging of the RC charging circuit by designing a control module to obtain the calibration time when the energy storage capacitor is charged to a preset target voltage, determining the error between the capacity of the actual energy storage capacitor in the RC charging circuit and the theoretical energy storage capacitor by the difference between the calibration time and the preset theoretical time, that is, determining the error in the RC time constant, and determining the compensation capacitance value by the difference relationship between the calibration time and the preset theoretical time, and finally controlling the number of energy storage capacitor units connected to the capacitor network according to the compensation capacitance value through the control circuit, thereby achieving the purpose of RC time constant calibration while efficiently and accurately obtaining the RC time constant deviation, and quickly compensating and incorporating the capacitor unit through the integrated system synchronization and flexible configuration, and the system structure is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 Schematic diagram of the architecture of an RC time constant calibration system based on an ADC system provided by the present invention;

[0036] Figure 2 1 is a schematic diagram of a circuit structure provided by an embodiment of the present invention;

[0037] Figure 3 1 is a control logic diagram of the capacitor charging calibration time provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0039] It should be noted that the RC time constant calibration system based on the ADC system provided by the present invention includes a hardware device and a software program arranged in the hardware device. Figure 1 , the RC time constant calibration system based on the ADC system provided by the embodiment of the present invention is introduced in detail.

[0040] See Figure 1 , provides a schematic diagram of the architecture of an RC time constant calibration system based on an ADC system according to an embodiment of the present invention. Figure 1 As shown, the system of the embodiment of the present invention may include:

[0041] RC charging circuit 1: The RC charging circuit is used to charge the energy storage capacitor to a preset target voltage;

[0042] It should be noted that, in this embodiment, the RC charging circuit is a circuit having an RC time constant to be calibrated, and the application scenario and composition structure of the RC charging circuit are not limited in this embodiment.

[0043] Furthermore, the preset target voltage is an arbitrary voltage value, which is set by the number and connection method of the resistors in the RC charging circuit. The RC time constant in the RC charging circuit is τ=RC. Therefore, in this embodiment, the time constant is calibrated based on the capacitance.

[0044] In a specific embodiment, see Figure 2, the RC charging circuit includes a single-pole double-control switch 11, a first resistor 12, a storage capacitor 13, a second resistor 14, a third resistor 15 and a comparator 16;

[0045] The first contact of the single-pole double-control switch is electrically connected to the control module, and the second contact of the single-pole double-control switch is connected to one end of the first resistor;

[0046] The other end of the first resistor is connected to one end of the energy storage capacitor, and the other end of the energy storage capacitor is grounded;

[0047] One end of the second resistor is connected to the common end of the single-pole double-control switch, and the other end is connected to one end of the third resistor, and the other end of the third resistor is grounded;

[0048] The first input end of the comparator is connected between the first resistor and the energy storage capacitor, the second input end of the comparator is connected between the second resistor and the third resistor, and the output end of the comparator is connected to the control module.

[0049] In this embodiment, the comparator is used to compare the real-time voltage of the energy storage capacitor with the preset target voltage. The real-time voltage of the energy storage capacitor when charging and the preset target voltage are input into the comparator through the two input terminals of the comparator for comparison.

[0050] It should be noted that the control module feeds back the charging switch signal of the RC charging circuit based on the output of the comparator. Specifically, the control module is directly connected to the single-pole double-control switch and controls the contact connection of the single-pole double-control switch. When the value charged to the energy storage capacitor is greater than the preset target voltage value at the other end of the comparator, a high level is output, and the single-pole double-control switch is connected to the first contact and disconnected from the second contact. When the value charged to the energy storage capacitor is less than the preset target voltage value at the other end of the comparator, a low level is output, and the single-pole double-control switch is connected to the second contact to continuously charge the energy storage capacitor.

[0051] It should be noted that, in this embodiment, the preset target voltage is determined by the values ​​of the second resistor and the third resistor.

[0052] Therefore, through the RC charging circuit provided in this embodiment, the deviation of the RC time constant can be indirectly calculated without additional process steps or major changes to the structure or chip structure. In combination with the calibration system provided in the embodiment of the present invention, the RC time constant can be calibrated simply by incorporating a certain amount of resistance to control the preset target voltage and a certain amount of capacitance as a compensation capacitance. The system structure is simple and efficient.

[0053] Control module 2: The control module is used to control the charging on and off of the RC charging circuit and record the calibration time when the energy storage capacitor is charged to a preset target voltage; determine the compensation capacitance value based on the difference between the calibration time and the preset theoretical time;

[0054] It should be noted that the control module controls the disconnection and connection of the single-pole double-control switch according to the level signal output by the comparator, thereby starting or stopping the charging of the energy storage capacitor. When calibrating the RC time constant based on the capacitor, the calibration time used to charge the energy storage capacitor to the preset target voltage is first obtained. When there is an error in the RC time constant, there must be an error between the calibration time and the preset theoretical time. Therefore, the deviation of the RC time constant is indirectly fed back through the calibration time, where the calibration time may be too long or too short. The deviation between the calibration time and the preset theoretical time is used to determine the size of the parallel capacitor value, thereby compensating for the RC time constant by connecting a capacitor of a certain value in parallel.

[0055] In a specific embodiment, the control module further includes a capacitance calculation unit;

[0056] The capacitance calculation unit is used to determine the compensation capacitance value according to the following formula:

[0057]

[0058] Among them, floor is the rounding function, which means taking the maximum integer value that does not exceed the current number; U all Compensation capacitance value; T is the preset theoretical time; rc cyc is the calibration time; f is the frequency of the clock used to record the calibration time when the capacitor is charged to the preset target voltage during the capacitor charging process.

[0059] In this embodiment, the number of capacitor units can be obtained based on the difference between the calibration time and the preset theoretical time. In order to eliminate the error of the timer, the capacitance value is calculated by calculating the ratio of the calibration time to the clock frequency as the absolute value of the calibration time.

[0060] It should be noted that U all The capacitance value required to compensate for the Tus rc time is also the size of the capacitance matrix that can be selected. In this embodiment, 192 is selected, and finally a binary capacitance value that needs to be compensated is obtained through floor.

[0061] Capacitor network 3: The capacitor network includes a plurality of capacitor units connected in parallel, and the control module is further configured to control the number of energy storage capacitor units connected to the capacitor network according to the compensation capacitance value.

[0062] In this embodiment, the capacitor network serves to provide compensation capacitance. Therefore, in this embodiment, the specific structure of the capacitor network, the number of capacitors, etc. are not limited.

[0063] In some embodiments of the present invention, see Figure 1 and Figure 2 , further comprising a temperature code decoder 4;

[0064] The temperature code decoder 4 is communicatively connected between the control module and the capacitor network, and is used to convert the compensation capacitance value into a temperature code;

[0065] The control module is further configured to determine the number of energy storage capacitor units connected to the capacitor network according to the number of bits of the temperature code, that is, to control the temperature code decoder to select the number of capacitors to be connected in parallel by the capacitance value.

[0066] In a specific embodiment, the temperature code decoding logic is as follows:

[0067] When the binary code determined by the capacitance calculation unit is 1, the temperature code is 00001;

[0068] When the binary code determined by the capacitance calculation unit is 2, the temperature code is 00011

[0069] When the binary code determined by the capacitance calculation unit is 3, the temperature code is 00111

[0070] When the binary code determined by the capacitance calculation unit is 4, the temperature code is 01111

[0071] When the binary code determined by the capacitance calculation unit is 5, the temperature code is 11111

[0072] The number of bits of the temperature code depends on the number of capacitors in the capacitor matrix. Each 1 in the temperature code corresponds to the switch of a capacitor.

[0073] In some embodiments, see Figure 1 , the control module also includes a timing unit 21,

[0074] The timing unit is used to record the calibration time when the real-time voltage of the energy storage capacitor during charging is equal to the preset target voltage.

[0075] In this embodiment, the calibration time for the energy storage capacitor to be charged to the preset target voltage is recorded by a timing unit, and then compared with the preset theoretical time, so as to indirectly obtain the error of the RC time constant.

[0076] In a specific embodiment, see Figure 3 , Figure 3The first figure is the counting clock, and the second figure is the switching signal that controls the RC circuit. The digital control logic first controls the switching signal of the RC circuit for one counting clock cycle, and then checks whether the comparator output flips. If not, it continues to control the switching signal of the RC circuit for two counting clock cycles, and then checks whether the comparator output flips. If not, it continues to repeat the above operations. When the comparator flips, the switching signal of the RC circuit at this time is stored in the memory. This completes one calibration process, and the calibration time is recorded by the timing unit.

[0077] In some embodiments, the control module further includes a configuration unit 22;

[0078] The configuration unit is used to determine the interval range of the real-time calibration time according to the preset theoretical time, and configure the clock counting period for recording the calibration time when the energy storage capacitor is charged to the preset target voltage according to the interval range of the real-time calibration time.

[0079] In this embodiment, to speed up the search and improve the efficiency of RC time constant calibration, the configuration unit configures the counting clock period of the RC circuit's switching signal to not start with a single counting clock period. The range of possible calibration time intervals is determined based on a preset theoretical time, and the clock counting period is configured based on this range, effectively shortening the calibration period and improving calibration efficiency.

[0080] In some embodiments of the present invention, the configuration unit is further configured to configure the number of calibration times for obtaining the energy storage capacitor when charging to a preset target voltage.

[0081] In this embodiment, in order to eliminate the influence of comparator noise on the result, the digital control logic is configured through the configuration unit. For example, the calibration process is configured to be 8 times, and the calibration process is repeated 8 times to calculate the arithmetic mean, and this arithmetic mean is used as the final calibration time.

[0082] After the control module obtains the final calibration value, it can obtain the difference from the target RC constant by converting the relationship between clock frequency and capacitance. At this time, the error capacitor is selected from the pre-designed capacitor network and connected in parallel with the existing capacitor to complete the calibration.

[0083] In some embodiments of the present invention, the configuration module further includes a calibration time calculation unit 23;

[0084] The calibration time calculation unit is further configured to perform an average calculation based on the obtained number of calibration times when the energy storage capacitor is charged to a preset target voltage to obtain a target calibration time.

[0085] In a specific embodiment, when the value obtained after the first calibration process is 100 counting cycles, 100 is recorded first, and the second calibration is started according to the above calibration method. The value obtained after the second calibration is completed is 101 counting cycles, and then the third calibration is started. The value obtained after the calibration is completed is 102 counting cycles, and finally the results of the three times are averaged: floor((100+101+102) / 3)=101, the floor function is to take the maximum integer that does not exceed the current integer, that is, round down, and finally 101 becomes the clock cycle value for the final capacitance value conversion.

[0086] The present invention has the following beneficial effects: by designing a control module to control the charging of the RC charging circuit to obtain the calibration time when the energy storage capacitor is charged to a preset target voltage, the difference between the calibration time and the preset theoretical time is used to determine whether there is an error between the capacity of the actual energy storage capacitor in the RC charging circuit and the theoretical energy storage capacitor, that is, it is determined that there is an error in the RC time constant, and the compensation capacitance value is determined by the difference relationship between the calibration time and the preset theoretical time. Finally, the control circuit controls the number of energy storage capacitor units connected to the capacitor network according to the compensation capacitance value, thereby achieving the purpose of RC time constant calibration while efficiently and accurately obtaining the RC time constant deviation, and the capacitor units are synchronously and flexibly configured and quickly compensated through the integrated system, and the system structure is simple.

[0087] The above disclosure is merely a preferred embodiment of the present invention and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. An RC time constant calibration system based on an ADC system, characterized in that: include: RC charging circuit, capacitor network and control module; RC charging circuit, used to charge its own energy storage capacitor to a preset target voltage; a capacitor network comprising a plurality of capacitor units connected in parallel; A control module is used to control the charging on and off of the RC charging circuit, to record the calibration time when the energy storage capacitor is charged to a preset target voltage, to determine the compensation capacitance value based on the difference between the calibration time and the preset theoretical time, and to control the number of capacitor units in the capacitor network connected to the RC charging circuit based on the compensation capacitance value.

2. The RC time constant calibration system based on the ADC system according to claim 1, characterized in that: The RC charging circuit includes a single-pole double-control switch, a first resistor, the energy storage capacitor, a second resistor, a third resistor and a comparator; The first contact of the single-pole double-control switch is electrically connected to the control module, and the second contact of the single-pole double-control switch is connected to one end of the first resistor; The other end of the first resistor is connected to one end of the energy storage capacitor, and the other end of the energy storage capacitor is grounded; One end of the second resistor is connected to the common end of the single-pole double-control switch, and the other end is connected to one end of the third resistor, and the other end of the third resistor is grounded; The first input end of the comparator is connected between the first resistor and the energy storage capacitor, the second input end of the comparator is connected between the second resistor and the third resistor, and the output end of the comparator is connected to the control module.

3. The RC time constant calibration system based on the ADC system according to claim 2, characterized in that: The second resistor and the third resistor form a voltage-dividing resistor network to determine a preset target voltage, and the preset target voltage is input to the second input terminal of the comparator.

4. The RC time constant calibration system based on the ADC system according to claim 3, characterized in that: The input parameter of the first input terminal of the comparator is the real-time voltage of the energy storage capacitor when it is charged; The comparator is used to compare the real-time voltage of the energy storage capacitor when it is charged with a preset target voltage, and transmit the comparison result to the control module through the output terminal; The control module includes a start-stop control unit, which is used to control the single-pole double-control switch to disconnect from the second contact when the real-time voltage is equal to the preset target voltage, and stop charging the energy storage capacitor; The start-stop control unit is further configured to control the single-pole double-control switch to be continuously connected to the second contact to charge the energy storage capacitor when the real-time voltage is less than a preset target voltage.

5. The RC time constant calibration system based on the ADC system according to claim 1, characterized in that: The control module also includes a timing unit, The timing unit is used to record the calibration time when the real-time voltage of the energy storage capacitor during charging is equal to the preset target voltage.

6. The RC time constant calibration system based on the ADC system according to claim 1, characterized in that: The control module further includes a capacitance calculation unit; The capacitance calculation unit is used to determine the compensation capacitance value according to the following formula: Among them, floor is the rounding function, which means taking the maximum integer value that does not exceed the current number; U all Compensation capacitance value; T is the preset theoretical time; rc cyc is the calibration time; f is the frequency of the clock used to record the calibration time when the capacitor is charged to the preset target voltage during the capacitor charging process.

7. The RC time constant calibration system based on the ADC system according to claim 1, characterized in that: Also includes a temperature code decoder; The temperature code decoder is communicatively connected between the control module and the capacitor network, and is used to convert the compensation capacitance value into a temperature code; The control module is further configured to determine the number of energy storage capacitor units connected to the capacitor network according to the number of digits of the temperature code.

8. The RC time constant calibration system based on the ADC system according to claim 1, characterized in that: The control module further includes a configuration unit; The configuration unit is used to determine the interval range of the real-time calibration time according to the preset theoretical time, and configure the clock counting period for recording the calibration time when the energy storage capacitor is charged to the preset target voltage according to the interval range of the real-time calibration time.

9. The RC time constant calibration system based on the ADC system according to claim 8, characterized in that: The configuration unit is further configured to configure the number of calibration times for obtaining the energy storage capacitor when charging to a preset target voltage.

10. The RC time constant calibration system based on the ADC system according to claim 9, characterized in that: The configuration module also includes a calibration time calculation unit; The calibration time calculation unit is further configured to perform an average calculation based on the obtained number of calibration times when the energy storage capacitor is charged to a preset target voltage to obtain a target calibration time.

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