KR102073309B1 - Gas sensor system - Google Patents

Abstract

According to the present invention, a gas sensor system comprises: an R-DAC outputting a voltage corresponding to a resistance value of a variable resistor as a first voltage; an I-DAC outputting a voltage corresponding to a current value flowing through the variable resistor as a second voltage; a reusable comparator comparing the first voltage or the second voltage with a predetermined reference value to output a comparison signal; a C-DAC receiving the residual voltage amplified to a predetermined level provided by the reusable comparator and outputting an analog signal generated through sampling to the reusable comparator; and a control unit receiving the output of the reusable comparator, adjusting each DAC array value of the R-DAC, the I-DAC, and the C-DAC and outputting a digital code of voltage conversion output from the reusable comparator. Accordingly, power consumption can be reduced.

Description

Gas sensor system {GAS SENSOR SYSTEM}

The present invention relates to a gas sensor system, and more particularly, a comparator for operating an R-DAC and an I-DAC, and an amplifier for operating a C-DAC with a residual voltage remaining after the R-DAC. The present invention relates to a gas sensor system.

In general, semiconductor gas sensor systems applied to various industrial fields, such as IOT, vehicle air quality management, and industrial disaster prevention, can detect (analyze) the gas concentration by detecting a change in resistance value according to the gas concentration. have.

To this end, semiconductor gas sensor systems require a resistive digital to analog converter (R-DAC) and a current digital to analog converter (I-DAC) to convert resistance into voltage, depending on the configuration. .

In addition, the semiconductor gas sensor system requires a capacitive digital to analog converter (C-DAC) because a SAR ADC (Successive Approximation Register Digital to Analog Converter) is used to convert the changed voltage into a digital code.

In addition, the semiconductor gas sensor system requires a comparator for operating the R-DAC and the I-DAC, and a separate amplifier for operating the C-DAC with the residual voltage remaining after the R-DAC. do.

However, the conventional semiconductor gas sensor system has a problem in that the size of the entire system becomes large because the comparator and the amplifier must be provided separately, and the power consumption increases due to separate components.

Korean Patent Registration No. 10-1840683 (Announcement Date: March 21, 2018) Korean Patent Publication No. 2012-0065806 (Published: 2012. 06. 21)

The present invention proposes a gas sensor system capable of sharing a comparator for operating an R-DAC and an I-DAC and an amplifier for operating a C-DAC with a residual voltage remaining after the R-DAC.

The problem to be solved by the present invention is not limited to the above-mentioned, another problem to be solved is not mentioned can be clearly understood by those skilled in the art from the following description. will be.

According to an aspect of the present invention, a resistance digital to analog converter (R-DAC) for outputting a voltage corresponding to a resistance value of a variable resistor as a first voltage and a voltage corresponding to a current value flowing through the variable resistor are provided. Current Digital to Analog Converter (I-DAC) outputting a second voltage, a reuse comparator for outputting a comparison signal by comparing a predetermined reference value with the first voltage or the second voltage, and the reuse comparator Provides a C-DAC (Capacitive Digital to Analog Converter) for receiving a residual voltage amplified to a predetermined level provided from the output unit and outputting an analog signal generated through sampling to the reuse comparator, and an output of the reuse comparator A controller for adjusting the DAC array values of the R-DAC, the I-DAC, and the C-DAC, and outputting a digital code of a voltage conversion output from the reuse comparator It can provide a gas sensor system including.

The R-DAC of the present invention may include a resistor array in which a plurality of resistors are connected in parallel.

The R-DAC of the present invention is a coarse resistance value of the variable resistor using a binary search algorithm that sequentially connects the value of the resistor array from the MSB (most significant bit) to the LSB (least significant bit). You can find

The I-DAC of the present invention may be configured as a current source array in which a plurality of current sources are connected in parallel.

The I-DAC of the present invention uses a binary search algorithm that sequentially connects the value of the current source array from the MSB (most significant bit) to the LSB (least significant bit) in order to obtain a fine resistance value of the variable resistor. You can find

The C-DAC of the present invention may be configured as a capacitor array in which a plurality of capacitors are connected in parallel.

The C-DAC, the reuse comparator, and the controller of the present invention may function as a Successive Approximation Register Analo 0g-to-Digital Converter (SAR ADC).

According to an embodiment of the present invention, the comparator for operating the R-DAC and the I-DAC and the amplifier for operating the C-DAC with the residual voltage remaining after the R-DAC are shared, thereby reducing the design area of the entire system. In addition, power consumption can be reduced by using a single shared element.

Further, according to the embodiment of the present invention, stable voltage transfer can be realized at the time of amplifying the residual voltage.

In addition, according to an embodiment of the present invention, the design of the dynamic amplifier insensitive to PVT, it is possible to minimize the resulting change due to the surrounding environment when measuring the gas sensor.

1 is a block diagram of a gas sensor system according to an embodiment of the present invention.
FIG. 2 is an array structure diagram of the R-DAC shown in FIG. 1.
FIG. 3 is an array structure diagram of the I-DAC shown in FIG. 1.
4 is an array structure diagram of the C-DAC shown in FIG. 1.
5 is a circuit diagram of the reuse comparator shown in FIG. 1.

First, the advantages and features of the present invention, and a method for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. Herein, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the embodiments of the present invention make the disclosure of the present invention complete, and it is common in the art to which the present invention belongs. The technical scope of the present invention should be defined by the claims, since it is provided by way of example so that those skilled in the art can clearly understand the scope of the invention.

In addition, in the following description of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may be changed according to intention or custom of a user, an operator, or the like. Therefore, the definition should be made based on the technical idea described throughout this specification.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

1 is a block diagram of a gas sensor system according to an embodiment of the present invention.

Referring to FIG. 1, the gas sensor system according to the present embodiment includes a resistance digital to analog converter (R-DAC) 102, a current digital to analog converter (I-DAC) 104, and a capacitive digital to C-DAC (C-DAC). An analog converter 106, a reuse comparator 108, a controller 110, and the like.

The first switch SW1 is provided between the variable resistor Rsens and the input of the R-DAC 102, and the second switch SW2 is provided between the variable resistor Rsens and the input of the I-DAC 104. Is provided. Here, the variable resistor may also be defined as a sensor resistor.

In addition, a third switch SW3 is provided between the output of the R-DAC 102 and the input of the reuse comparator 108 and the fourth between the output of the I-DAC 104 and the input of the reuse comparator 108. A switch SW4 is provided, and a fifth switch SW5 is provided between the output of the C-DAC 106 and the input of the reuse comparator 108.

First, the R-DAC 102 is configured to divide the resistance when the first switch SW1 and the third switch SW3 are on (all other switches are off) for a coarse process. dividing) generates (outputs) a voltage corresponding to the resistance value of the variable resistor as a first voltage (a voltage corresponding to the current value flowing through the variable resistor), and reuses the comparator through a path via the third switch SW3. Serve as an input of 108.

To this end, the R-DAC 102 may be configured as an array of resistors in which a plurality of resistors are connected in parallel, as shown in FIG. 2 as an example. Here, the variable resistor using a binary search algorithm that sequentially connects the resistance array value from the MSB (most significant bit) to the LSB (least significant bit) according to the DAC control (adjustment control of the DAC array value) from the controller 110 to be described later. Find the coarse resistance of.

In addition, the I-DAC 104 has a variable resistor Rsens when the second switch SW2 and the fourth switch SW4 are on (all the remaining switches are off) for a fine process. ) To generate (output) a voltage corresponding to the current value flowing through the variable resistor as a second voltage and provide it to the input of the reuse comparator 108 through a path via the fourth switch SW4. Can be performed.

To this end, the I-DAC 104 may be configured as a current source array in which a plurality of current sources are connected in parallel, as shown in FIG. 3 as an example. Here, a binary search algorithm that sequentially connects the current source array values from the MSB (most significant bit) to the LSB (least significant bit) according to DAC control (control control of the DAC array value) from the control unit 110 to be described later. It can be used to find the fine resistance value of the variable resistor.

Next, the C-DAC 106 receives a residual voltage amplified (eg, 4 times amplification, 16 times amplification, etc.) to a predetermined level provided from the reuse comparator 108 and receives sampling through sampling. The analog signal may be output and provided as an input of the reuse comparator 108 through the fifth switch SW5.

To this end, the C-DAC 106 may be configured as a capacitor array in which a plurality of capacitors are connected in parallel, as shown in FIG. 4 as an example.

On the other hand, the reuse comparator 108 may be connected to the first voltage provided from the R-DAC 102 through the third switch SW3 or the second voltage provided from the I-DAC 104 through the fourth switch SW4. Compare the predetermined reference value and output the first comparison signal to the controller 110, compare the analog signal output from the C-DAC 106 with the predetermined reference value, and output the second comparison signal to the controller 110, etc. Can provide the function of.

Here, the reuse comparator 108 may function as a comparator, a residual voltage amplifier, a pre-amplifier of a loop filter, or the like, and may have a circuit configuration as shown in FIG. 5 for this purpose.

In this case, when the reusable comparator 108 is used as an amplifier, gain can be adjusted to, for example, 4 and 16. According to the present invention, an additional amplifier can be used without the need for an additional amplifier, and a separate sampling can be performed. It can be used as a dynamic amplifier in a formless process, minimizing power consumption and area.

5 is a circuit diagram of the reuse comparator 108 shown in FIG.

Referring to FIG. 5, when the reuse comparator 108 operates as a comparator, when the RESET switches SW21 and SW23 are turned on, the CLK_CINV (SW22 and SW24) is turned off.

In this case, the Lz + and Lz− nodes are charged to VDD. At this time, F8 and F10 are turned off as PMOS. In the case of F9 and F11, since the RESET switches SW21 and SW23 are on, the NMOS is turned on and the voltage between F8 and F9, F10 and F11 becomes zero.

Thus, through the buffers 202 and 204, VO + and VO- give an output of zero.

After that, when the reset is completed and the comparison starts, when the RESET switches SW21 and SW23 are turned off and the CLK_CINV is turned on, the voltages of Lz + and Lz- are applied to the voltages VIN + and VIN- applied to F5 and F6. Discharge proceeds in proportion to, and when discharged to a specific level, the PMOS of F8 and F10 is turned on, and VO + and VO- are changed to a high level.

At this time, since one of VIN + and VIN- is larger, the voltage of one of Lz + and Lz- drops relatively quickly, so that one of F8 and F10 turns on first. Therefore, it is comparable that the higher the voltage, the higher the voltage among VO + and VO- first.

In addition, when the reuse comparator 108 operates as an amplifier, the discharge is in progress, and when the comparison is completed, Lz + and Lz- have a certain voltage, which is controlled by a capacitor attached to Lz + and Lz-, The voltages of Lz + and Lz- have an amplified effect on the input voltage.

Therefore, the gain can be adjusted to 4 and 16 by adjusting the capacitor value. In other words, if the time for opening CLK_CINV is relatively lowered, the gain becomes 4, which is a small gain. If the time for opening CLK_CINV is relatively increased, the gain can be adjusted up to 16 degrees.

Here, F7 may function as a use for completely resetting the residual voltage which may exist below F5, F6, F2, and F4 at the reset timing.

F1 and F3 may be turned on when the switch is high when the loop filter is operated, and turned off when the filter is low. In addition, F2 and F4 are portions for applying the input of the loop filter, and VNS + and VNS- may refer to voltages applied through the loop filter.

Referring back to FIG. 1, the controller 110 receives the output of the reuse comparator 108 to adjust the values of the respective DAC arrays of the R-DAC 102, the I-DAC 104, and the C-DAC 106. The digital code of the voltage conversion output from the reuse comparator 108 may be provided to a micro-controller unit (MCU) 112.

Here, the residual value after the voltage comparison is amplified to a predetermined level and sent to the C-DAC 106, the fifth switch SW5 is turned on, and all the remaining switches SW1 to SW4 are turned off, thereby providing the C-DAC ( 106), the reuse comparator 108 and the controller 110 may be configured in the form of a SAR ADC (Successive Approximation Register Analog-to-Digital Converter), through which sampling and SAR ADC conversion may be performed.

The MCU 112 is for performing overall operation control of the gas sensor system. The MCU 112 may refer to a module that is responsible for processing and controlling a gas concentration by analyzing a digital code provided from the controller 110. Can be.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains various substitutions, modifications, changes, etc., without departing from the essential characteristics of the present invention. You will easily see this possible. That is, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments.

Therefore, the protection scope of the present invention should be interpreted by the claims to be described later, and all technical ideas within the equivalent scope will be construed as being included in the scope of the present invention.

102: R-DAC
104: I-DAC
106: C-DAC
108: reuse comparator
110: control unit

Claims (7)

A resistance digital to analog converter (R-DAC) for outputting a voltage corresponding to the resistance of the variable resistor as a first voltage;
A current digital to analog converter (I-DAC) for outputting a voltage corresponding to a current value flowing through the variable resistor as a second voltage;
A reuse comparator for comparing the first voltage or the second voltage with a predetermined reference value and outputting a comparison signal;
A capacitive digital to analog converter (C-DAC) for receiving a residual voltage obtained by amplifying the residual value of the comparison signal to a predetermined level and outputting an analog signal generated through sampling to the reuse comparator;
The output of the comparison signal of the reuse comparator is provided to adjust the value of each DAC array of the R-DAC, the I-DAC, and the C-DAC, and digitally converts the voltage to the comparison signal output from the reuse comparator. Control to output the code
Gas sensor system comprising a. The method of claim 1,
The R-DAC,
Consists of an array of resistors in which multiple resistors are connected in parallel
Gas sensor system. The method of claim 2,
The R-DAC,
Finding the coarse resistance value of the variable resistor using a binary search algorithm that sequentially connects the values of the resistor array from the MSB (most significant bit) to LSB (least significant bit).
Gas sensor system. The method of claim 1,
The I-DAC,
Consists of an array of current sources in which multiple current sources are connected in parallel
Gas sensor system. The method of claim 4, wherein
The I-DAC,
Finding the fine resistance value of the variable resistor using a binary search algorithm that sequentially connects the value of the current source array from MSB (most significant bit) to LSB (least significant bit).
Gas sensor system. The method of claim 1,
The C-DAC,
Consists of a capacitor array in which multiple capacitors are connected in parallel
Gas sensor system. The method of claim 1,
The C-DAC, the reuse comparator and the control unit may function as a Successive Approximation Register Analo 0g-to-Digital Converter (SAR ADC).
Gas sensor system.

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