KR100983788B1 - an interface circuit for multi-element gas sensor - Google Patents

Abstract

Disclosed are signal processing circuits for various sensor arrays that reduce power consumption by reducing the number of repetitive resistors in the application of the bridge circuit structure and at the same time maximize the dynamic range characteristics of the gas sensor. The circuit comprises N resistors; A sensor array comprising N sensors; Selection means for electrically connecting one of the N sensors and one of the N resistors in accordance with a selection signal; A first resistor, one end of which is electrically connected to the N resistors; And a second resistor electrically connected between the other end of the first resistor and the N sensors of the sensor array, where N is an integer greater than or equal to two.

Multiple sensor arrays, instrumentation amplifier circuits, AD conversions, bridge circuits

Description

Signal processing circuit for multi-sensor arrays

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to circuits for signal processing of a variety of sensor arrays using bridge circuits. In particular, in the application of bridge circuit structures, power consumption is reduced by reducing the number of repetitive resistors, and at the same time, the dynamic range of the gas sensor is reduced. The present invention relates to signal processing circuits for various types of sensor arrays that make the best use of the characteristics.

1 is a diagram illustrating an example of a measurement circuit of a resistance gas sensor.

As shown in FIG. 1, a resistance type gas sensor measuring circuit has a large number of bridge type circuit structures that are easy to change in resistance and offset correction according to temperature and surrounding environment.

In such a bridge type circuit, a circuit that outputs an output resistance value according to gas sensing of a sensor Rsen as a voltage difference, or converts a resistance change into a frequency using an RC resonant circuit (not shown), and outputs it to be.

Therefore, in order to signal process a plurality of gas sensor arrays, a plurality of overlapping bridge circuits are required. In other words, when multiple gas sensors are used to simultaneously detect several types of gases, N pairs of bridge resistors are required when the number of gases to be detected is N. However, when using a plurality of redundant bridge circuits as described above, there is a problem in that the number of resistors required for the circuit configuration increases and thus the power consumption increases. In addition, such a bridge circuit has a problem that it does not sufficiently utilize the dynamic range characteristics of the sensor.

Accordingly, an object of the present invention is to reduce the power consumption by reducing the number of repetitive resistance in the application of the bridge circuit structure for the signal processing of the N-channel resistance type multi-array array gas sensor, and at the same time the dynamic range of the gas sensor It is to provide a signal processing circuit for multiple sensor arrays that can improve the characteristics.

According to an aspect of the present invention, there is provided a signal processing circuit for a multi-sensor sensor array comprising: N resistors; A sensor array comprising N sensors; Selection means for electrically connecting one of the N sensors and one of the N resistors in accordance with a selection signal; A first resistor, one end of which is electrically connected to the N resistors; And a second resistor electrically connected between the other end of the first resistor and the N sensors of the sensor array, where N is an integer greater than or equal to two.

Advantageously, said selecting means comprises: a first multiplexer for selecting one of said N sensors in accordance with said selection signal; And a second multiplexer for electrically connecting one of the N resistors to an output terminal of the first multiplexer according to the selection signal. In addition, a reference voltage is generated from a connection node of the first and second resistors, and a sense voltage is generated at the output terminal of the first multiplexer.

More preferably, the signal processing circuit for the plurality of sensor arrays further includes an instrumentation amplifier circuit for amplifying the reference voltage and the sense voltage and an AD converter for converting the output of the instrumentation amplifier circuit into a digital signal.

Also preferably, the signal processing circuit for the plurality of sensor arrays further includes an N-bit counting circuit for counting pulses output from the instrumentation amplifier circuit, wherein the N-bit counting circuit comprises an output terminal of the instrumentation amplifier circuit. Schmitt trigger connected to; An N-bit counter for counting pulses input from the Schmitt trigger; A capacitor connected in parallel to a feedback resistor of the instrumentation amplifier circuit; And a transistor switched according to an output signal of the Schmitt trigger and connected to both ends of the capacitor.

A signal processing circuit for a multiple sensor array according to a second aspect of the present invention comprises N resistors; A sensor array comprising N sensors; First means for selecting one of the sensors of the sensor array in accordance with a selection signal; Second means for selecting one of the resistors in accordance with the selection signal and electrically connecting the sensor selected by the first means and the selected resistor; A first resistor, one end of which is electrically connected in parallel with the two or more resistors; And a second resistor electrically connected to the other end of the first resistor and one end thereof, the other end of which is electrically connected in parallel with the sensors of the sensor array, wherein N is an integer greater than or equal to 2 A reference voltage is generated from the connection node of the first and second resistors, and the sensing voltage of the selected sensor is generated through the connection node of the sensor and the resistor selected by the selection means, respectively.

Preferably, each of said first and second means is a multiplexer of N: 1.

According to the present invention, it is possible to reduce the power consumption by reducing the number of repetitive resistances in the application of the bridge structure for signal processing of the N-channel resistive multi-array sensors, and at the same time maximize the dynamic range of each of the multi-channel sensor array It is possible to process the signal, thereby increasing the resolution of the output digital signal.

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

2 is a view showing an example of a structure of a resistance type multi-gas sensor array applied to the present invention.

3 is a circuit diagram illustrating a signal processing circuit for various types of sensor arrays according to an exemplary embodiment.

FIG. 4 is a circuit diagram illustrating an AD conversion circuit connected to an output terminal that may be applied to signal processing circuits for various sensor arrays shown in FIG. 3.

5 and 6 are waveform diagrams for describing the operation of the circuit shown in FIGS. 3 and 4.

As shown in FIG. 2, the resistive multi-gas sensor array structure applied to the present invention has a plurality of multi-gas sensors formed on one substrate, and is typically used to process sensing signals sensed by each sensor. As shown in Figure 1, a bridge circuit must be configured for each sensor.

In order to overcome the duplication of such bridge circuit components, as shown in FIG. 3, the signal processing circuit for the multiple sensor array according to the embodiment of the present invention includes N resistors Rbias # 1, Rbias # 2,. ..., Rbias # N), sensor array 100 comprising N sensors (Rsen # 1, Rsen # 2, ..., Rsen # N), one of the N sensors according to the selection signal A first multiplexer 200 for selecting a, one of the N resistors (Rbias # 1, Rbias # 2, ...., Rbias # N) and the first multiplexer 200 according to the selection signal A second multiplexer 300 for electrically connecting an output terminal, a first resistor Rb of which one end is electrically connected to the N resistors Rbias # 1, Rbias # 2, ..., Rbias # N. ), And a second resistor electrically connected between the other end of the first resistor Rb and the N sensors Rsen # 1, Rsen # 2, ..., Rsen # N of the sensor array 100. Ra). Wherein N is an integer of 2 or more.

A reference voltage Vref is generated from the connection nodes of the first and second resistors Rb and Ra, and a sensing voltage Vsen # 1-#N is generated at the output terminal of the first multiplexer 200.

In addition, the signal processing circuits for the various sensor arrays may include an instrumentation amplifier circuit for differentially amplifying the reference voltage Vref and the sense voltages Vsen # 1 to #N. 400 and an AD converter 500 for converting the output of the instrumentation amplifier circuit 400 into a digital signal.

Further, according to the present invention, the signal processing circuit for the various sensor arrays further includes an N-bit counting circuit 600 for counting pulses output from the instrumentation amplifier circuit 400.

The N-bit counting circuit 600 is in parallel with a Schmitt trigger connected to an output terminal of the instrumentation amplifier circuit 400, an N-bit counter for counting pulses input from the Schmitt trigger, and a feedback resistor of the instrumentation amplifier circuit. And a capacitor Ca for removing switching noise, and a transistor switched according to an output signal of the Schmitt trigger and connected to both ends of the capacitor Ca.

According to the above configuration, as shown in FIG. 5, when a selection signal from the outside is input to the first and second multiplexers 200 and 300, the N resistors Rbias # 1, Rbias # 2,... One of Rbias # N and one of N sensors Rsen # 1, Rsen # 2, ..., Rsen # N are selected so that the first and second resistors Rb and Ra are selected. Together with the bridge circuit. When a bridge circuit is constructed, the reference voltage Vref and the connection of the first multiplexer 200 and the second multiplexer 300 are connected from the connection nodes of the first and second resistors Rb and Ra of the bridge circuit. The sense voltages Vsen # 1-Vsen # N are generated from the node. According to the selection signal, the first and second multiplexers 200 and 300 are configured to provide the sensors Rsen # 1, Rsen # 2, ..., Rsen # N and the resistors Rbias # 1, Rbias #. 2, ..., and Rbias # N are sequentially selected, the sensing voltages detected by the N sensors (Rsen # 1, Rsen # 2, ..., Rsen # N) according to the selection order. Vsen # 1-Vsen # N and reference voltages Vref are generated in turn, and these voltages are in turn input to the instrumentation amplifier circuit 400.

When the reference voltage Vref and the sensing voltages Vsen # 1 to Vsen # N, which are sequentially generated, are input to the instrumentation circuit 400, the reference voltage Vref and the sensing voltages Vsen # 1 to Vsen # N ) Are differentially amplified and output to the AD converter 500 and the N-bit counting circuit 600, respectively. Then, the AD converter 500 converts the amplified sense voltage as a sense signal into a digital signal, and outputs the digital signal. As illustrated in FIG. 6, the N-bit counting circuit 600 triggers a Schmitt trigger of the sense voltage. By generating a digital signal according to the on / off of, and providing this digital signal externally as an MSB, it is possible to increase the output resolution of the sense signal, and to improve the output dynamic range.

Figure 6 (a) shows the characteristics of the output voltage value compared to the gas sensor resistance value of the conventional circuit, (b) shows an example of the output characteristics implemented in the circuit of the present invention. (b) As shown in the graph, when the output voltage reaches a certain high value (upper trigger voltage of the Schmitt trigger circuit), it is automatically reset, and when it falls to some lower value (low trigger voltage of the Schmitt trigger circuit), the gas concentration is returned. It begins to charge with a voltage value proportional to. The circuit of the present invention has been shown to be a signal processing circuit utilizing the dynamic range characteristic of the gas sensor more sufficiently than the conventional circuit.

Therefore, according to the present invention, two N: 1 multiplexers are used to configure N sensor resistors, N split resistors, and one first and second resistors R1 and R2 for generating a reference voltage Vref. Thus, the circuit structure can be simplified and the power consumption can be minimized.

In addition, the circuit according to the present invention can be applied to not only a resistance type multi gas sensor array, but also a multi environment sensor or a bio sensor array.

Although the present invention has been described as a specific preferred embodiment, the present invention is not limited to the above-described embodiments, and the present invention is not limited to the above-described embodiments without departing from the gist of the present invention as claimed in the claims. Anyone with a variety of variations will be possible.

1 is a view showing an example of a measurement circuit of a conventional resistance gas sensor.

2 is a view showing an example of a structure of a resistance type multi-gas sensor array applied to the present invention.

3 is a circuit diagram illustrating a signal processing circuit for various types of sensor arrays according to an exemplary embodiment.

FIG. 4 is a circuit diagram illustrating an AD conversion circuit connected to an output terminal that may be applied to signal processing circuits for various sensor arrays shown in FIG. 3.

5 and 6 are waveform diagrams for describing the operation of the circuit shown in FIGS. 3 and 4.

Claims (13)

N resistors; A sensor array comprising N sensors; Selection means for electrically connecting one of the N sensors and one of the N resistors in accordance with a selection signal; A first resistor, one end of which is electrically connected to the N resistors; A second resistor electrically connected between the other end of the first resistor and the N sensors of the sensor array, N is an integer of 2 or more, signal processing circuit for a plurality of sensor arrays. The method of claim 1, The selection means includes a first multiplexer for selecting one of the N sensors in accordance with the selection signal; And And a second multiplexer for electrically connecting one of the N resistors and an output terminal of the first multiplexer according to the selection signal. The method of claim 1, A reference voltage is generated from the connection node of the first and second resistors, and the sensing voltage of the selected sensor is generated through the connection node of the sensor and the resistor selected by the selection means, respectively. Signal processing circuit. The method of claim 3, wherein The signal processing circuit for the various sensor arrays further comprises an instrumentation amplifier circuit for differentially amplifying the reference voltage and the sense voltage. The method of claim 4, wherein The signal processing circuit for the various sensor arrays And an AD converter for converting the output of the instrumentation amplifier circuit into a digital signal. The method according to claim 4 or 5, The signal processing circuit for the various sensor arrays And n-bit counting circuitry for counting pulses output from said instrumentation amplifier circuit. The method of claim 6, The N-bit counting circuit is A Schmitt trigger coupled to the output of the instrumentation amplifier circuit; An N-bit counter for counting pulses input from the Schmitt trigger; A capacitor connected in parallel to a feedback resistor of the instrumentation amplifier circuit; And And a transistor switched according to an output signal of the Schmitt trigger and connected to both ends of the capacitor. N resistors; A sensor array comprising N sensors; First means for selecting one of the sensors of the sensor array in accordance with a selection signal; Second means for selecting one of the resistors in accordance with the selection signal and electrically connecting the sensor selected by the first means and the selected resistor; A first resistor, one end of which is electrically connected in parallel with the two or more resistors; And A second resistor electrically connected to the other end of the first resistor and one end thereof, the other end of which is electrically connected in parallel with the sensors of the sensor array; Here, N is an integer greater than or equal to 2, a reference voltage is generated from the connection node of the first and second resistors, and a sensing voltage of the selected sensor is generated through the connection node of the sensor and the resistor selected by the selection means, respectively. Signal processing circuit for a plurality of sensor arrays, characterized in that. The method of claim 8, And each of said first and second means is a multiplexer of N: 1. 10. The method according to claim 8 or 9, The signal processing circuit for the various sensor arrays further comprises an instrumentation amplifier circuit for differentially amplifying the reference voltage and the sense voltage. The method of claim 10, The signal processing circuit for the various sensor arrays And an AD converter for converting the output of the instrumentation amplifier circuit into a digital signal. The method of claim 10, The signal processing circuit for the various sensor arrays And n-bit counting circuitry for counting pulses output from said instrumentation amplifier circuit. 13. The method of claim 12, The N-bit counting circuit is A Schmitt trigger coupled to the output of the instrumentation amplifier circuit; An N-bit counter for counting pulses input from the Schmitt trigger; A capacitor connected in parallel to a feedback resistor of the instrumentation amplifier circuit; And And a transistor switched according to an output signal of the Schmitt trigger and connected to both ends of the capacitor.

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