GB2591166A

GB2591166A - Amplifying device and radiation detection apparatus including the same

Info

Publication number: GB2591166A
Application number: GB2016768.0A
Authority: GB
Inventors: Kwon Inyong; Lee Changyeop; Jeon Hyuntak; Cho Gyuseong; Je Minkyu; Kim Duckhyun; Jhung Seungho; Shin Dongseong
Original assignee: Korea Atomic Energy Research Institute KAERI
Current assignee: Korea Atomic Energy Research Institute KAERI
Priority date: 2018-10-17
Filing date: 2019-10-17
Publication date: 2021-07-21
Anticipated expiration: 2039-10-17
Also published as: GB2591166B; GB2579444A9; GB201915041D0; GB2579444B; GB202016768D0; GB2579444A

Abstract

An amplifying device 1000 comprises a charge sensitive amplifier (CSA) 1100 with negative feedback provided by a resistor and a capacitor between the input and output terminals, and a replica amplifier 1200 configured to receive a constant input signal. A self-compensation unit 1300 is configured to adjust a gain bandwidth (GBW) product of the CSA in response to an output signal of the replica amplifier to compensate for a change in the output signal of the CSA. The self-compensation unit may be configured to increase a current, or reduce a total capacitance (Fig.17, Cc1-Ccn), of the CSA when the replica amplifier’s output signal amplitude reduces. Alternatively, an amplifying device (Fig.1, 200) for amplifying a signal from a radiation sensor includes a signal amplifier and an output unit; the signal amplifier comprises first and second amplifiers for amplifying an input signal and an offset signal, respectively. The output unit generates a digital output signal indicating a difference between the amplified input and offset signals. Additionally, a radiation detection apparatus (Fig.1, 1) includes a radiation detection unit, the amplifying device (Fig.1, 200), and a communication unit to transmit the digital output signal to an external device. The amplifying device may be used to compensate for a change in amplifier characteristics due to radiation.

Description

AMPLIFYING DEVICE AND RADIATION DETECTION APPARATUS INCLUDING THE SAME

Field of the Invention

The present disclosure relates to an amplifying device, and more particularly to, an amplifying device for amcplifying signals and outputting the amplified signals, and a radiation detection aNpaiatas including the same.

Background of the Invention

As is well known, radiation has been widely used in various fields in our real lives, for example, including aerospace, defense, non-destructive testing, radiological analysis, age-dating of materials, fabrication of petrochemical products, medical devices, sterilization, food processing, new materials, breed improvement, etc. In all the above technical fields, radiation instrumentation is essential for radiation exposure, production of high-quality products, etc. In order to measure radiation, a sensor must be used, and a radiation detection device designed to measure radiation using the sensor needs to have robust radiation-resistant properties even in a radiation environment.

Meanwhile, a signal output from the sensor for measuring radiation is configured in the form of a voltage or current, and a circuit used to amplify the output signal of the sensor in an initial stage is a pre-amplifier. Generally, the pre-amplifier is mainly implemented as a charge sensitive amplifier (CSA) that has superior linearity based on the magnitude of the output signal of the sensor. The CSA may include a resistor and a capacitor that are disposed between an input terminal and an output terminal thereof, such that the signal output from the CSA may be fed back to the input terminal of the CSA in a negative manner.

However, although the pre-amplifier is implemented as the CSA having excellent linearity, there occurs a change in characteristics affected by radiation, for example, a reduction in amplitude, an increase in noise, a fall time, 15 etc. The above-mentioned changes in characteristics affected by radiation may degrade linearity of the preamplifier, and may also degrade performance of the entire signal measurement and processing system.

Summary of the Invention

The present disclosure has been made in view of the above problems, and it is an object of the present disclosure to provide an amplifying device for generating an output signal that is acquired when an offset signal is removed from an input signal having a radiation signal, and a radiation detection apparatus including the same.

It is another object of the present disclosure to provide an amplifying device for self-compensating for an output signal in response to a change in characteristics affected by the operating environment such as radiation.

It will be appreciated by persons skilled in the art that the objects that could be achieved with the present disclosure are not limited to what has been particularly described hereinabove and the above and other objects that the present disclosure could achieve will be more clearly understood from the following detailed description.

In. accordance with a first ascect of the present invention, there is provided an amplifying device including: a signal amplifier including a first amplifier for amplifying an input signal containing a radiation signal to output a first amplified signal, and a second amplifier for amplifying an offset signal to output an amplified offset signal; and an output unit configured to generate and output a digital output signal indicating a difference between the first amplified signal and the amplified offset signal.

In accordance second aspect of the present invention, there is provided a radiation detection apparatus including: a radiation detection unit configured to detect radiation, and output a radiation signal corresponding to the detected radiation; an amplifying device configured to amplify an input signal including the radiation signal to output an first amplified signal, amplify an offset signal to output an amplified offset signal, and generate a digital output signal indicating a difference between the first amplified signal and the amplified offset signal; and a communication unit configured to transmit the digital output signal to an external device.

In accordance with a second aspect of the present. invention, there is provided an amplifying device including: a CSA (charge sensitive amplifier) type amplifier with a transistor structure, wherein the CSA type amplifier includes an input terminal, an output terminal, a resistor and a capacitor, and the resistor and the capacitor are disposed between the input terminal and the output terminal, and an output signal output through the output terminal of the CSA type amplifier is fed back to the input terminal in a negative manner; a replica amplifier configured to receive a constant input signal to output an output signal; and a self-compensation unit configured to adjust a gain bandwidth product (GBW) value of the CSA type amplifier in response to a change in the output signal of the replica amplifier outputted based on the constant input signal, and compensate for a change in the output signal of the CSA type amplifier.

Effect of the Invention According to the embodiment of the present disclosure, since the offset signal generated by the influence of radiation is removed from the input signal, the characteristic change of the circuit caused by the radiation can be eliminated, thereby the reliability of The radiation detection can be ensured. As a result, embodiments of the present disclosure can be applied to a number of environments in which high level radiation is likely to leak. Further, the amplifying device according to the embodiment of the present disclosure can self-compensate for 10 the output signal thereof in response to a change in characteristics affected by the operating environment such as radiation. Therefore, although changes in characteristics, for example, reduction in output amplitude, increased noise, a fall time, occur in the amplifying device due to the influence of radiation, the amplifying device can self-compensate for such changed characteristics, such that signal linearity and system performance may not be deteriorated by such radiation and the entire signal measurement and processing system may thus normally operate.

When the present disclosure is applied to all kinds of measurement systems to which radiation is applied, the present disclosure may prevent performance of each measurement system from being degraded by radiation. As a result, the present disclosure can increase a replacement period of the measurement system, resulting in reduction in costs. In addition, since the amplifying circuits of the present disclosure can stably operate even in a radiation environment, a circuit system including the amplifying circuits can be operated without degrading performance.

The effects of the present disclosure are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from following description.

Brief Description of the Drawings

Fig. 1 is a functional block diagram illustrating a radiation detection apparatus according to a first embodiment of the present disclosure.

Fig. 2 is a circuit diagram schematically illustrating a radiation sensor of a radiation detection unit of the radiation detection apparatus according to the first embodiment of the present disclosure.

Fig. 3 is a graph of a radiation signal that is output from the radiation sensor of the radiation detection unit of the radiation detection apparatus according to the first

embodiment of the present disclosure.

Fig. 4 is a circuit diagram illustrating an amplifying device of the radiation detection apparatus according to the first embodiment of the present disclosure.

Fig. 5 is a functional block diagram illustrating a radiation detection apparatus according to a second

embodiment of the present disclosure.

Fig. 6 is a circuit diagram illustrating an amplifying device of the radiation detection apparatus according to the second embodiment of the present disclosure.

Fig. 7 is a circuit diagram illustrating a Charge Sensitive Amplifier (CSA) type amplifier (hereinafter referred to as a CSA amplifier) for amplifying an output signal of the sensor.

Fig. 8 is a graph illustrating output signals measured in a state in which the CSA amplifier shown in Fig. 7 is exposed to Cobalt-60 gamma-ray up to Total Ionizing Dose (TID) of 2 Mrad.

Fig. 9 is a graph illustrating reduction in bandwidth according to a change in voltage gain and a Total Ionizing Dose (TID) effect based on frequency.

Fig. 10 is a block diagram illustrating an amplifying device according to a third embodiment of the present disclosure.

Fig. 11 is a circuit diagram illustrating a self-compensation unit of the amplifying device according to the

third embodiment of the present disclosure.

Fig. 12 is a waveform diagram illustrating an output signal of a comparator of the amplifying device according to the third embodiment of the present disclosure.

Fig. 13 is a graph illustrating changes in amplitude at current values of 50 pA and 67 pA when the CSA amplifier is exposed to TID of 2 Mrad.

Fig. 14 is a graph illustrating changes in signal to noise ratio (SNR) at current values of 50 TJA and 67 pA when the CSA amplifier is exposed to TID of 2 Mrad.

Fig. 15 is a graph illustrating changes in fall time at current values of 50 pA and 67 pA when the CSA amplifier is exposed to TID of 2 Mrad.

Fig. 16 is a graph illustrating an output signal of the CSA amplifier and the output signal based on an increasing current in a state in which the CSA amplifier is exposed to Cobalt-60 gamma-ray up to TID of 5.5 Mrad.

Fig. 17 is a circuit diagram illustrating a self-compensation unit of an amplifying device according to a fourth embodiment of the present disclosure.

Detailed Description of the Embodiments

The advantages and features of embodiments and methods of accomplishing these will be clearly understood from the following description taken in conjunction with the accompanying drawings. However, embodiments are not limited to those embodiments described, as embodiments may be implemented in various forms. It should be noted that the present embodiments are provided to make a full disclosure and also to allow those skilled in the art to know the full range of the embodiments. Therefore, the embodiments are to be defined only by the scope of the appended claims.

In describing the embodiments of the present disclosure, if it is determined that detailed description of related known components or functions unnecessarily obscures the gist of the present disclosure, the detailed description thereof will be omitted. Further, the terminologies to be described below are defined in consideration of functions of the embodiments of the present disclosure and may vary depending on a user's or an operator's intention or practice.

Accordingly, the definition thereof may be made on a basis

of the content throughout the specification.

In the following description, the terms "... unit", " part", portion", " ... module", etc. denote a unit of processing at least one function or operation, and may be 15 implemented by hardware, software, or a combination of hardware and software.

Hereinafter, an amplifying device and a radiation detection apparatus according to embodiments of the present disclosure will be described with reference to Figs. 1 to 17.

Fig. 1 is a functional block diagram illustrating a radiation detection apparatus 1 according to a first embodiment of the present disclosure.

Referring to Fig. 1, the radiation detection apparatus 1 according to the first embodiment may be installed at a plurality of positions where radiation is likely to leak outside, and may transmit a radiation signal corresponding to the radiation detected at the corresponding positions to a remote server such as a central control room through wired/wireless communication. The remote server may monitor, in real time, information about the presence or absence of radiation leakage, information about the position of such radiation leakage, and the like based on the received radiation signal.

To this end, the radiation detection apparatus 1 according to the first embodiment includes a radiation detection unit 100 for detecting radiation and outputting a radiation signal corresponding to the detected radiation, an amplifying device 200 for generating an output signal obtained by amplifying the radiation signal and converting the amplified radiation signal into a digital signal, and a communication unit 300 for transmitting the output signal to an external device.

The radiation detection unit 100 includes a radiation sensor capable of detecting such radiation. The radiation sensor according to one embodiment may be designed to have a large surface area. More particularly, the radiation sensor according to one embodiment may be formed in a planar shape. The planar radiation sensor may include a sub-sensor array provided at one surface thereof. Hereinafter, the circuit configuration and operation of the radiation sensor according to one embodiment of the present disclosure will be described with reference to Figs. 2 and 3.

Fig. 2 is a circuit diagram illustrating a radiation sensor of a radiation detection unit of the radiation detection apparatus according to the first embodiment of the present disclosure. Fig. 3 is a graph of a radiation signal that is output from the radiation sensor of the radiation detection unit of the radiation detection apparatus according to the first embodiment of the present disclosure. Referring to Fig. 2, the radiation sensor according to one embodiment Includes a plurality of sub-sensors arranged in a two-dimensional (2D) shape to form a sub-sensor array.

Each of the sub-sensors may operate by a high reverse voltage applied to a Ph junction semiconductor.

Each of the sub-sensors may include a diode, a resistor, and a capacitor. One end of the diode, one end of the resistor, and one end of the capacitor may be connected to a single node. In each sub-sensor, a node nn formed by the other end of the diode may be set to a sub-cathode, a node nn formed by the other end of the resistor may be set to a sub-anode, and a node n13 formed by the other end of the capacitor may be set to a sub-fast output node.

The radiation sensor may connect the plurality of sub-sensors in parallel, resulting in formation of cathodes, anodes, and fast output nodes. In more detail, in the radiation sensor, a node n1 connected to the sub-cathodes of the respective sub-sensors may be set to the cathode, a node n2 connected to the sub-anodes of the respective sub-sensors may be set to the anode, and the node n2 connected to the sub-fast output nodes of the respective sub-sensors may be set to the fast output node.

Referring to the right lower side of Fig. 2, when radiation is applied in directions of arrows, The radiation sensor may detect the applied radiation, and may output a radiation signal corresponding to the detected radiation, as a charge-shaped radiation signal, through the anode n2 of the radiation sensor. Fig. 3 exemplarily illustrates the radiation signal that is output through the anode n2 of the radiation sensor.

Referring to Fig. 3, the radiation signal may be rapidly output within a short period of time, such that the radiation signal may have a short pulse width. In addition, the radiation signal may be configured in the form of a voltage based on the amount of charges, and the voltage may be proportional to the charge generation efficiency of the radiation sensor. In this case, as the reverse voltage applied to the radiation sensor increases within a maximum 20 allowable voltage of the radiation sensor, the charge generation efficiency of the radio sensor may also increase. Referring back to Fig. 1, the communication unit 300 may receive the radiation signal from the radiation detection unit 100 through the amplifying device 200, and may transmit the received radiation signal to the external device located at a remote site. Here, the ex7_ernal device may refer to all external devices, each of which is capable of processing, analyzing, and using the radiation signal, and may be implemented in the form of a server or a cloud. For example, when the radiation detection apparatus 1 is installed at a plurality of positions within a nuclear power plant, the external device may be implemented as a management server installed in the central control room that monitors the presence or absence of radiation leakage in the nuclear power plant.

The external device having received the radiation signal may directly analyze information about the presence or absence of radiation leakage, the position of the radiation leakage, and the like in a monitoring region where the radiation detection apparatus 1 is installed, and may provide a user with the analyzed information. Further, it may provide the user with basic information needed for such analysis.

For communication with the external device, the communication unit 300 according to one embodiment of the present disclosure may transmit the radiation signal to the external device after passing through a base station according to a wireless communication scheme such as 3rd generation (3G) communication, 4 generation (4G) communication, etc. In contrast, the communication unit 300 according to another embodiment of the present disclosure may also transmit the radiation signal to the external device within a predetermined distance through a communication scheme such as Wireless LAN (WLAN), WI-Fi, Bluetooth, Wi-Fi Direct (WFD), Ultra WideBand (UWB), Infrared Data Association (IrDA), Bluetooth Low Energy (ELM,

Near Field Communication (NFC), etc.

In particular, since the communication unit 300 capable of performing ZigBee wireless communication is constructed by a digital circuit, the communication unit 300 may be less affected by radiation than the case in which the communication unit 300 is implemented as an analog circuit.

The amplifying device 200 may amplify the radiation signal output from the radiation detection unit 100, and may convert the amplified radiation signal into a digital signal, resulting in formation of an output signal. In this case, since the amplifying device 200 is implemented as an integrated circuit, erroneous operation or malfunction may occur in the amplifying device 200 due to radiation desired to be detected. In particular, when radiation leakage occurs in the nuclear power plant, the radiation detection apparatus 1 installed in the nuclear power plant to monitor the presence or absence of radiation leakage may be directly exposed to radiation, such that the radiation detection apparatus 1 may abnormally operate.

Specifically, the amplifying device 200 implemented as an integrated circuit may abnormally operate due to a Total Ionizing Dose (TIE)) effect caused by exposure to radiation.

In the integrated circuit including one or more transistors formed of a metal oxide semiconductor material, one or more holes thereof are trapped into an oxide material by radiation. As a result, a threshold vollage of the transistor may be changed or a leakage current may occur, such that the radiation signal having passed through the amplifying device 200 may cause unexpected errors.

In order to address the above-mentioned issues, the trapped hole may be tunneled by applying a process of 100nm or less to the integrated circuit contained in the amplifying device 200, or the integrated circuit may be designed either as a transistor configured in the form of a closed gate or as a Bipolar Junction Transistor (BJT). However, when the amplifying device 200 is designed using the above-mentioned methods, there is a possibility that product costs of the amplifying device 200 may increase. Accordingly, the radiation detection apparatus 1 according to one embodiment may interpret the influence of the analog circuit affected by the TIP effect as an offset signal, and may remove the offset signal from an output signal thereof, such that influences of radiation can be excluded from the output signal. That is, the offset signal is a signal related to the degree to which the amplifying device 200 is affected by the radiation signal.

Specifically, as shown in Fig. 1, the amplifying device 200 according to one embodiment includes a signal amplifier 210, an output unit 230, and a buffer 220. The signal amplifier 210 includes a first amplifier 211 configured to amplify an input signal including the radiation signal, and a second amplifier 212 configured to amplify the offset signal. The output unit 230 may generate a digital signal indicating a difference between the amplified input signal and the amplified offset signal, and may output the digital signal as the output signal. The buffer 220 may Include a first buffer 221 configured to transmit the amplified input signal to the output unit 230, and a second buffer 222 configured to transmit the amplified offset signal to the output unit 230.

Constituent elements of the amplifying device 200 according to the first embodiment of the present disclosure will hereinafter be described with reference to Fig. 4.

Fig. 4 is a circuit diagram illustrating the amplifying device 200 of the radiation detection apparatus 1 according to the first embodiment of the present disclosure.

Referring to Fig. 4, the signal amplifier 210 includes the first amplifier 211 and the second amplifier 212, each of which independently receives a signal. The first amplifier 211 may include a first amplifying unit, a resistor RFB and a capacitor C connected in parallel to the first amplifying unit. The second amplifier 212 may include a second amplifying unit, a resistor R:3 and a capacitor CFB connected in parallel to the second amplifying unit.

A reference voltage VDD/2 corresponding to a half of a drive voltage may be applied to a positive (+) input terminal of the first amplifying unit, and a capacitor Cm of the radiation detection unit 100 may be connected to a negative (-) input terminal of the first amplifying unit. In this case, the radiation detection unit 100 may include a resistor Rs and a capacitor Cm that are connected in parallel to the anode of the radiation sensor connected to a bias voltage Vbtas. The resistor Rs and the capacitor Cm may serve to perform conversion of the radiation signal outputted from the radiation sensor. That is, the resistor Rs and the capacitor Cm may convert a current signal into a voltage signal in association with the radiation signal outputted from the radiation sensor.

As described above, since the radiation signal from the radiation detection unit 100 to the first amplifier 211 has a very short pulse width, the first amplifier 211 may integrate the received radiation signal through the first amplifier having a high bandwidth and a feedback capacitor CFB and may thus output the integrated signal. In this case, the signal output from the first amplifier 211 may have an amplitude proportional to the amount of integrated charges, and may be restored to a DC voltage according to a settling time proportional to a time constant (T =RF3 X CF3) of the feedback capacitor CFs and the feedback resistor RM.

On the other hand, the input signal applied through the negative (-) input terminal of the first amplifier 211 may include not only the radiation signal but also an offset signal caused by the TED effect. As a result, the first amplifier 211 may amplify the input signal including both the radiation signal and the offset signal, and may thus output the amplified signal.

A reference voltage VLD/2 corresponding to a half of the drive voltage may be applied to the positive (+) input terminal of the second amplifier 212. On the other hand, unlike the first amplifier 211, the second amplifier 212 may be connected to a ground terminal through the capacitor Cm, connected to the negative (-) input terminal thereof. As a result, the second amplifier 212 may amplify only the offset signal, and may thus output only the amplified offset signal.

The buffer 220 may output the input signal amplified by the first amplifier 211 and the offset signal amplified by the second amplifier 212 to the output unit 230 to be described later. The buffer 220 may charge a sampling capacitor of a digital converter 231 contained in the output unit 230, and may perform a buffering function in a manner that the digital converter 231 does not directly receive the amplified signal from the signal amplifier 210. In addition, the buffer 220 may also prevent the output signal of the signal amplifier 210 from being distorted by charge injection of the digital converter 231.

To this end, the buffer 220 may include the first buffer 221 configured to transmit the input signal amplified by the first amplifier 211 to the output unit 230, and the second buffer 222 configured to transmit the offset signal amplified by the second amplifier 212 to the output unit 230.

The first buffer 221 may receive the input signal amplified by the first amplifier 211, and may output an amplified radiation signal Vst, and an amplified offset signal Vrad. On the other hand, the second buffer 222 may receive the offset signal amplified by the second amplifier 212, and may output only the amplified offset signal Vrad.

The output unit 230 may generate a digital signal indicating a difference between the amplified input signal and the amplified offset signal, and may output the generated digital signal as an output signal thereof. For this purpose, the output unit 230 according to one embodiment may include a digital converter 231 and a subtractor 232. The digital converter 231 may include a first converter 231a configured to convert the amplified input signal into a digital input signal, and a second converter 231b configured to convert the amplified offset signal into a digital offset signal. The subtractor 232 may generate an output signal by calculating a difference between the digital input signal and the digital offset signal.

Referring to Fig. 4, the first converter 231a may be connected to an output terminal of the first buffer 221, and may thus receive the amplified radiation signal Vst, and the amplified offset signal Vrad. The first converter 231a may convert the received signals Vsig and Vrad into digital signals. To this end, the first converter 231a may be implemented as an Analog-to-Digital Converter (ADC) for converting an analog signal into a digital signal.

The second converter 231b may be connected to an output terminal of the second buffer 222, and may thus receive the amplified offset signal Vrad. The second converter 231b may convert the input signal Vrad into a digital signal. To this end, the second converter 231b may also be implemented as an Analog-to-Digital Converter (ADC) in the same manner as in the first converter 231a.

The subtractor 232 may calculate a difference between the digital signal output from the first converter 231a and the other digital signal output from the second converter 231b, and may thus generate a final output signal D,a based on the calculated difference. The digital signal output from the first converter 231a may include information about the radiation signal and information about the offset signal.

The digital signal output from the second converter 231b may include information about the offset signal, so that the output signal Dmfl of the subtractor 232 may correspond to a signal in which the offset signal is removed from the radiation signal and the offset signal.

As a result, the amplifying device 200 may transmit only the radiation signal from which the offset signal is excluded to the communication unit 300, and the radiation detection apparatus 1 may transmit only the radiation signal to the external device through the communication unit 300.

Heretofore, the exemplary case in which the output unit 230 includes two converters has been described for convenience of description. The output unit 230 of the amplifying device 200 according to another embodiment may include only one converter, and as such a detailed description thereof will hereinafter be described with reference to Figs. 5 and 6.

Fig. 5 is a functional block diagram illustrating a radiation detection apparatus 1 according to a second embodiment of the present disclosure. Fig. 6 is a circuit diagram illustrating an amplifying device of the radiation detection apparatus 1 according to the second embodiment of the present disclosure.

The radiation detection apparatus 1 according to the embodiment shown in Figs. 5 and 6 may include a radiation detection unit 100 for detecting radiation and outputting a radiation signal corresponding to the detected radiation, an amplifying device 200 for amplifying the radiation signal, converting the amplified radiation signal into a digital signal, and generating a digital output signal, and a communication unit 300 for transmitting the digital output signal to an external device.

The amplifying device 200 according to the embodiment shown in Figs. 5 and 6 may include a signal amplifier 210, an output unit 230, and a buffer 220. The signal amplifier 210 may include a first amplifier 211 configured to amplify an input signal including the radiation signal, and a second amplifier 212 configured to amplify the offset signal. The output unit 230 may generate a digital signal indicating a difference between the amplified input signal and the amplified offset signal, and may output the digital signal as the output signal. The buffer 220 may Include a first buffer 221 configured to transmit the amplified input signal to the output unit 230, and a second buffer 222 configured to transmit the amplified offset signal to the output unit 230.

Constituent elements of the radiation detection apparatus 1 and the amplifying device 200 according to the embodiment shown in Figs. 5 and 6 may be identical in structure to the remaining constituent elements other than the output unit 230 of the amplifying device 200 contained in the radiation detection apparatus 1 shown in Figs. 1 to 4, as such redundant matters thereof will herein be omitted for brevity, and the following embodiment will hereinafter be described centering upon the output unit 230.

Referring to Figs. 5 and 6, the output unit 230 according to one embodiment of the present disclosure may include a differential input digital converter 233 for generating an output signal by converting a difference between the amplified input signal and the amplified offset signal into a digital signal.

In more detail, the differential input digital converter 233 may receive the amplified radiation signal Vsig and the amplified offset signal V,d by connecting to the output terminal of the first buffer 221, and, at the same time, may receive the amplified offset signal Vrdd by connecting to the output terminal of the second buffer 222.

The differential input digital converter 233 may convert only a difference in received analog signals, i.e., only the amplified radiation signal Vsig, into a digital signal, and may thus generate an output signal thereof.

The amplifying device and the radiation detection apparatus including the same according to the above-mentioned first and second embodiments may remove the offset signal caused by radiation from the input signal, such that a change in circuit characteristics caused by such radiation can be excluded from the output signals of the amplifying device and the radiation detection apparatus, resulting in guarantee of high reliability of radiation detection. As a result, the embodiments of the present disclosure can be applied to numerous environments in which there is a high possibility that high-level radiation is likely to leak outside.

Fig. 7 is a circuit diagram illustrating a charge sensitive amplifier (CSA) type amplifier for amplifying an output signal of the sensor. Fig. 8 is a graph illustrating output signals measured in a state in which the CSA amplifier shown in Fig. 7 is exposed to Cobalt-60 gamma-ray up to Total Ionizing Dose (TID) of 2 Mrad.

Referring to Figs. 7 and 8, although the amplifier is implemented as the CSA amplifier having superior linearity, it can be seen that a change in characteristics such as a change in amplitude unavoidably occurs in the CSA amplifier due to occurrence of radiation.

A P-type Metal-Oxide Semiconductor Field Effect Transistor (MOSFET) may be relatively less affected by radiation than an N-type MOSFET, and an NPN-type Bipolar Junction Transistor (BJT) may be affected only by an increasing base current. Accordingly, research has been conducted on the CSA implemented as a Bipolar:unction transistor and Complemen7ary Metal Oxide Semiconductor (BiCMOS) formed by a combination of the P-type MOSFET and the NPN-type BJT, and the amplifier having the BiCMOS transistor structure is characterized in that a bandwidth thereof is gradually reduced in proportion to the increasing base current affected by radiation as shown in Fig. 9. Fig. 9 is a graph illustrating reduction in bandwidth according to a change in voltage gain and a TIT) effect based on frequency. The CSA amplifier implemented as the BiCMOS transistor formed by a combination of the P-type MOSFET and the NPN-type BJT may have a gain bandwidth product (GBW) represented by a product of a transconductance gm and a coupling conductance as as shown in the following equation 1. In Equation 2, the transconductance gm may be proportional to a current id. The amplifying device based on characteristics of the following equations 1 and 2 may self-compensate for an output signal thereof in response to a change in characteristics affected by the operating environment such as radiation.

(Equation 1) GBW = ' C, (Equation 2) 2c gm 17 J7 /, In Equations 1 and 2, Vgs is a gate voltage for a source terminal, and VU, is a threshold voltage.

Fig. 10 is a block diagram illustrating an amplifying device 1000 according to a third embodiment of the present disclosure.

Referring to Fig. 10, the amplifying device 1000 according to the third embodiment of the present disclosure includes an amplifier 1100, a replica amplifier 1200, and a self-compensation unit 130C.

The amplifier 1100 includes a resistor and a capacitor disposed between an input terminal and an output terminal thereof, such that the signal output from the amplifier 1100 may be fed back to the input terminal of the amplifier 1100 in a negative manner. The amplifier 1100 may be implemented as a CSA amplifier that includes a BiCMOS transistor formed by a combination of the P-type MOSFET and the NPN-type BST, or may also be implemented as the P-type MOSFET or the NPNtype BST as needed.

The replica amplifier 1200 may be formed by replication of the amplifier 1100, so that the replica amplifier 1200 may receive a constant signal as an input.

The self-compensation unit 1300 may adjust a GBW value of the amplifier 1100 according to a change in output signal of the replica amplifier 1200, such that the self-compensation unit 1300 may self-compensate for the change in output signal. The self-compensation unit 1300 may also adjust a GBW value of the replica amplifier 1200 according to a change in output signal of the replica amplifier 1200. For example, when the amplitude of the output signal of the replica amplifier 1200 is reduced, the self-compensation unit 1300 may increase a current of the amplifier 1100 and a current of the replica amplifier 1200 or may reduce total capacitance. In addition, when the amplitude of the output signal of the replica amplifier 1200 is reduced, the self-compensation unit 1300 may increase a current used to control the output signal of the amplifier 1100. In addition, when the amplitude of the output signal of the replica amplifier 1200 is reduced, the self-compensation unit 1300 may reduce total capacitance of the amplifier 1100. Fig. 11 is a circuit diagram illustrating the self-compensation unit 1300 of the amplifying device 1000 according to the third embodiment of the present disclosure.

Although Fig. 11 illustrates an exemplary case in which the output signal of the self-compensation unit 1303 is fed back to the amplifier 1100 and the replica amplifier 1200, the output signal of the self-compensation unit 1300 may be fed back only to the amplifier 1100 as needed.

Referring to Fig. 11, the self-compensation unit 1300 may include a comparator 1311, a shift register 1312, a pulse holder 1313, and a current steering 1314.

The comparator 1311 of the self-compensation unit 1300 may output a signal indicating information about the number of pulses corresponding to the amplitude of the output signal of the replica amplifier 1200.

The shift register 1312 of the self-compensation unit 1300 may shift the output pulse signal of the comparator 1311 by a predetermined distance corresponding to one pulse, and may thus output the shifted pulse signal.

The pulse holder 1313 of the self-compensation unit 1300 may separately delay each of the output pulses of the shift register 1312, and may output switching signals corresponding to the number of output pulses to the current steering 1314.

The current steering 1314 of the self-compensation unit 1300 may include a plurality of switches Yn, Yu Y2, Y3, Yfl, and may allow a drive voltage VB-to be fed back to each of the amplifier 1100 and the replica amplifier 1200, such that the drive voltage VB, may be supplied to the NPN-type BST contained in each of the amplifier 1100 and the replica amplifier 1200. In this case, the drive voltage VBE may be reduced or increased in response to the Increase or reduction in the number of some switches, which are switched by the switching signal of the pulse holder 1313, among the plurality of switches Yo, Y, Y2, 2 -Y 3 Y. * According to the amplifying device 1100 shown in Fig. 11, the output signal of the replica amplifier 1200 may be input to the comparator 1311, and the comparator 1311 may compare the output signal of the replica amplifier 1200 with a reference voltage and thus output a predetermined number of pulse signals corresponding to a width of the output signal of the replica amplifier 1200 as shown in Fig. 12. ;Each of the output pulse signals of the comparator 1311 may be shifted by the shift register 1312 by one pulse, and the shifted pulse may be separately delayed by the pulse holder 1313, such that as many switching signals as the number of output pulses may be simultaneously applied to the plurality of switches Y.J, Y1, Y2, Y.=, Yr, of the current steering 1314. ;Subsequently, a predetermined number of some switches among the total switches Yo, Y1, 1 / Y2 / Y3 * rYn contained in the current steering 1314 may be turned on in response to the number of output pulses of the pulse holder 1313. In more detail, the number of turned-ON switches may be identical to the number of output pulses of the pulse holder 1313. The current steering 1314 may control a voltage value V3E, having a magnitude corresponding to the number of turned-ON switches to be fed back to each of the amplifier 1100 and the replica amplifier 1200, such that each of the current of the amplifier 1100 and the current of the replica amplifier 1200 may be adjusted as much as the feedback voltage value V. If the amplifying device 1000 is driven in the radiation exposure environment, the amplitude of the output signal of the replica amplifier 1200 may be reduced due to influence of such radiation. As a result, the number of output pulses of the comparator 1311 of the self-compensation unit 1300 may be reduced in proportion to reduction in amplitude of the output signal of the replica amplifier 1200, and the number of turned-ON switches among the plurality of switches Yo, Yi, Y2, Y-3, Yn may also be reduced in proportion to the reduced number of output pulses, such that the output voltage value Vs.,E of the current steering 1314 may increase in response to reduction in the number of turned-ON switches. In addition, each of the current of the amplifier 1100 and the current of the replica amplifier 1200 may be adjusted to be high in response to the increasing voltage value VBE.

As described above, when the current of the amplifier 1100 and the current of the replica amplifier 1200 are increased by the self-compensation unit 1300, transconductance g11 may also increase as represented by the Equation 2, and a GBW value may also increase in proportion to the increasing transconductance gif as represented by the Equation 1. As a result, each of the GBW value of the amplifier 1100 and the GBW value of the replica amplifier 1200 can be self-compensated by a predetermined value corresponding to the influence of such radiation.

Referring to Figs. 13 to 17, it can be seen that amplitude, noise, and a fall time are less affected by radiation as the current of the amplifier 1100 and the current of the replica amplifier 1200 are increasing.

Fig. 13 is a graph illustrating changes in amplitude at current values of 50 pA and 67 pA when the CSA amplifier is exposed to TID of 2 Mrad. Fig. 14 is a graph illustrating changes in signal to noise ratio(SNR) at current values of 50 pA and 67 pA when the CSA amplifier is exposed to TIE) of 2 Mrad. Fig. 15 is a graph illustrating changes in fall time at current values of 50 pA and 67 pA when the CSA amplifier is exposed to TED of 2 Mrad. Fig. 16 is a graph illustrating output signals of the CSA amplifier in a state in which the CSA amplifier is exposed to Cobalt-gamma-ray up to TID of 5.5 Mrad and an output signal based on an increasing current.

Fig. 17 is a circuit diagram illustrating a self-compensation unit 1300 of an amplifying device 1000 according to a fourth embodiment of the presenT_ disclosure.

Although Fig. 17 illustrates an exemplary case in which an output signal of the self-compensation unit 1303 is fed back to each of an amplifier 1100 and a replica amplifier 1200, the output signal of the self-compensation unit 1300 can be fed back only to the amplifier 1100 as needed.

Referring to Fig. 17, the self-compensation unit 1300 includes a comparator 1321, a shift register 1322, and a pulse holder 1323. In this case, each of the amplifier 1100 and the replica amplifier 1200 includes a plurality of coupling capacitors Cci, Cc2, _, Con to determine total capacitance Cv. (i.e., Ct = Col + Cc2 + + Cc). Each of the amplifier 1100 and the replica amplifier 1200 includes a plurality of switching elements SWI, SW, SW. The plurality of switching elements SWI, SW2, SWn may correspond to the plurality of coupling capacitors Col, Cc2, Con on a one to one basis, and may be respectively paired with the plurality of coupling capacitors Col, Cc2, Cc,.

The comparator 1321 of the self-compensation unit 1300 may output a predetermined number of pulses corresponding to the amplitude of the output signal of the replica amplifier 1200.

The shift register 1322 of the self-compensation unit 1300 may shift the output pulses of the comparator 1321 by one pulse, and may thus output the shifted pulse signal to the pulse holder 1323.

The pulse holder 1323 of the self-compensation unit 1300 may separately delay each of the output pulses of the shift register 1322, and may thus output switching signals corresponding to the number of output pulses to the switching elements SW, SW2, , SW n of the amplifier 1100 and the switching elements SW1, SW2, ..., SW n of the replica amplifier 1200.

According to the amplifying device 1000 shown in Fig. 17, the output signal of the replica amplifier 1200 may be input to the comparator 1321, and the comparator 1321 may compare the output signal of the replica amplifier 1200 with a reference voltage and thus output a predetermined number of pulse signals corresponding to the width of the output signal of the replica amplifier 1200 as shown in Fig. 12.

Each of the output pulse signals of the comparator 1321 may be shifted by the shift register 1322 by one pulse, and the shifted pulse may be separately delayed by the pulse holder 1323, such that as many switching signals as the number of output pulses may be fed back to each of the amplifier 1100 and the replica amplifier 1200 and then input to the plurality of switches SW', SW2, ..., SW n of each of the amplifier 1100 and the replica amplifier 1200. Subsequently, a predetermined number of some switches among the total switches SW', SW2, ..., Sign may be turned on in response to the number of output pulses of the pulse holder 1323. In more detail, the number of turned-ON switches among the switches SW], SW2, SWn may be identical to the number of output pulses of the pulse holder 1323, such that total capacitance Ct (i.e., Col+ Cc2 +...+ Con) of each of the amplifier 1100 and the replica amplifier 1200 can be adjusted.

If the amplifying device 1000 is driven in the radiation exposure environment, the amplitude of the output signal of the replica amplifier 1200 may be reduced due to influence of such radiation. As a result, the number of output pulses of the comparator 1321 of the self-compensation unit 1300 may be reduced in proportion to reduction in amplitude of the output signal of the replica amplifier 1200, and the number of turned-ON switches among the plurality of switches SW1, SW2, ..., Sign may also be reduced in proportion to the reduced number of output pulses, such that total capacitance C_ (i.e., Col + Cc2 mi+ Con) of each of the amplifier 1100 and the replica amplifier 1200 may be reduced by a predetermined value corresponding to the reduced number of turned-ON switches.

As described above, when the coupling capacitance of the amplifier 1100 and the coupling capacitance of the replica amplifier 1200 are reduced by the self-compensation unit 1300, a GBW value may increase as represented by the Equation 1. As a result, each of the GBW value of the amplifier 1100 and the GEW value of the replica amplifier 1200 can be self-compensated by a predetermined value corresponding to the influence of such radiation.

As described above, the amplifying device according to the third and fourth embodiments of the present disclosure can self-compensate for the output signal thereof in response to a change in characteristics affected by the operating environment such as radiation. Therefore, although changes in characteristics (for example, reduction in output amplitude, increased noise, a fall time, etc.) occur in the amplifying device due to the influence of radiation, the amplifying device can self-compensate for such changed characteristics, such that signal linearity and system performance may not be deteriorated by such radiation and the entire signal measurement and processing system may thus normally operate.

As is apparent from the above description, when the present disclosure is applied to all kinds of measurement systems to which radiation is applied, the present disclosure may prevent performance of each measurement system from being degraded by radiation. As a result, the present disclosure can increase a replacement period (i.e., a lifespan) of the measurement system, resulting in reduction in costs. In addition, since the amplifying circuits of the present disclosure can stably operate, there is a lower possibility of radiation exposure.

The detailed description of the exemplary embodiments of the present disclosure has been given to enable those skilled in the art to implement and practice the invention.

Although the present disclosure has been described with reference to the preferred embodiments, those skilled in the art will appreciate that various modifications and variations can be made in the present disclosure without departing from the spirit or scope of the invention described in the appended claims. Accordingly, the present disclosure should not be limited to the specific embodiments described herein, but should be accorded the broadest scope consistent with the principles and novel features disclosed herein. In addition, while the present disclosure has been particularly shown and described with reference to exemplary embodiments thereof, various changes in form and detail may be made herein by those of ordinary skill in the art without departing from the spirit and scope of the present disclosure as defined by the following claims and such modifications and variations should not be understood separately from the technical idea or aspect of the present disclosure.

Claims

CLAIMS: 1. An amplifying device comprising: a CSA (charge sensitive amplifier) type amplifier with a transistor structure, wherein the CSA type amplifier includes an input terminal, an output terminal, a resistor and a capacitor, and the resistor and the capacitor are disposed between the input terminal and the output terminal, and an output signal output through the output terminal of the CSA type amplifier is fed back to the input terminal in a negative manner; a replica amplifier configured to receive a constant input signal to output an output signal; and a self-compensation unit configured to adjust a gain bandwidth product (GBW) value of the CSA type amplifier in response to a change in the output signal of the replica amplifier outputted based on the constant input signal, and compensate for a change in the output signal of the CSA type amplifier.
2. The amplifying device of claim 1, wherein the CSA type amplifier is one of a Bipolar junction transistor and Complementary Metal Oxide Semiconductor, a P-type Metal Oxide Semiconductor Field Effect Transistor, and an NPN-type Bipolar Junction Transistor.
3. The amplifying device of claim 1, wherein the self-compensation unit is configured to adjust a gain bandwidth product value of the replica amplifier in response to the change in the output signal of the replica amplifier outputted based on the constant input signal.
4. The amplifying device of claim 1, wherein the self-compensation unit is configured to increase a current of the CSA type amplifier when an amplitude of the output signal of the replica amplifier is reduced.
5. The amplifying device of claim 4, wherein the self-compensation unit includes: a comparator configured to output a predetermined 15 number of pulses corresponding to the amplitude of the output signal; a shift register configured to shift each of the output pulses of the comparator by one pulse; a pulse holder configured to separately delay each of 20 the output pulses of the shift register, and output a predetermined number of switching signals corresponding to the number of the output pulses; and a current steering including a plurality of switches, wherein a drive voltage that increases or decreases in response to an increase or a decrease in the number of one or more switches switched by the switching signals among the plurality of switches is supplied to the CSA type amplifier.
6. The amplifying device of claim 1, wherein the self-compensation unit is configured to reduce total capacitance of the CSA type amplifier when an amplitude of the output signal of the replica amplifier is reduced.
7. The amplifying device of claim 6, wherein the CSA type amplifier comprises: a plurality of coupling capacitors, and a plurality of switching elements configured to correspond to the plurality of coupling capacitors on a one to one basis, and to be respectively paired with the plurality of coupling capacitors, such that the total capacitance of the CSA type amplifier is determined through at least one of the plurality of coupling capacitors by execution of a switching operation, and wherein the self-compensation unit comprises: a comparator configured to output one or more pulses corresponding to the amplitude of the output signal, a shift register configured to shift the output pulses of the comparator by one pulse, and a pulse holder configured to separately delay each of the output pulses of the shift register, and output one or more switching signals corresponding to the number of the one or more output pulses to the plurality of switching elements.
6. An amplifying device comprising: a signal amplifier including a first amplifier for amplifying an input signal containing a radiation signal to output a first amplified signal, and a second amplifier for amplifying an offset signal to output an amplified offset signal; and an output unit configured to generate and output a digital output signal indicating a difference between the first amplified signal and the amplified offset signal.
9. The amplifying device of claim 8, wherein the offset signal includes a degree to which the amplifying device is affected by the radiation signal.
10. The amplifying device of claim 8, wherein the output unit includes: a digital converter including a first converter for converting the first amplified signal into a digital input signal, and a second converter for converting The amplified offset signal into a digital offset signal; and a subtractor configured to generate the digital output signal by calculating a difference between the digital input signal and the digital offset signal.
11. The amplifying device of claim 8, wherein the output unit includes: a differential input digital converter configured to convert the difference between the first amplified signal and the amplified offset signal into the digital output signal.
12. The amplifying device of claim 8, further comprising: a buffer including a first buffer that transmits the first amplified signal to the output unit, and a second buffer that transmits the amplified offset signal to the output unit.
13. The amplifying device of claim 10, further comprising: a buffer, wherein the buffer comprises: a first buffer that receives the first amplified signal from the first amplifier and outputs the first amplified signal to the first converter of the digital converter, wherein the first amplified signal includes an amplified radiation signal and the amplified offset signal; and a second buffer that receives the amplified offset signal from the second amplifier and outputs the amplified 25 offset signal to the second converter of the digital converter, wherein the first converter converts the amplified radiation signal and the amplified offset signal into a first digital signal, the second converter converts the amplified offset signal into a second digital signal, and the subtractor calculates a difference between the first digital signal corresponding to the radiation signal and offset signal digitally converted by the first converter and the second digital signal corresponding to the offset signal digitally converted by the second converter, and generates the digital output signal based on the calculated difference.
14. The amplifying device of claim 8, wherein an input terminal of the first amplifier is connected to a radiation detection unit to receive the radiation signal and the offset signal, and the radiation signal and the offset signal applied to the input terminal of the first amplifier are amplified such that the amplified radiation signal and the amplified offset signal are output through an output terminal of the first amplifier, and wherein an input terminal of the second amplifier is grounded to receive the offset signal, and the offset signal applied to the input terminal of the second amplifier is amplified such that the amplified offset signal is output through an output terminal of the second amplifier.
15. A radiation detection apparatus comprising: a radiation detection unit configured to detect radiation, and output a radiation signal corresponding to the detected radiation; an amplifying device configured to amplify an input signal including the radiation signal to output an first amplified signal, amplify an offset signal to output an amplified offset signal, and generate a digital output signal indicating a difference between the first amplified signal and the amplified offset signal; and a communication unit configured to transmit the digital output signal to an external device.
16. The radiation detection apparatus of claim 15, wherein the offset signal includes a degree to which the amplifying device is affected by the radiation signal.
17. The radiation detection apparatus of claim 15, wherein the amplifying device comprises: a signal amplifier including a first amplifier for amplifying the input signal to output the first amplified signal and a second amplifier for amplifying the offset signal to output the amplified offset signal; and an output unit configured to generate the digital output signal.
18. The radiation detection apparatus of claim 17, wherein the output unit comprises: a digital converter including a first converter for converting the first amplified signal into a first digital signal, and a second converter for converting The amplified offset signal into a second digital signal; and a subtractor configured to generate the digital output signal by calculating a difference between the first digital signal and the second digital signal.
19. The radiation detection apparatus of claim 17, wherein the output unit comprises: a differential input digital converter configured to convert the difference between the first amplified signal and the amplified offset signal into the digital output signal.
20. The radiation detection apparatus of claim 17, wherein the amplifying device further comprises: a buffer including a first buffer that transmits the first amplified signal to the output unit, and a second buffer that transmits the amplified offset signal to the output unit.
21. The radiation detection apparatus of claim 17, wherein an input terminal of the first amplifier is connected to a radiation detection unit to receive the radiation signal and the offset signal, and the radiation signal and the offset signal applied to the input terminal of the first amplifier are amplified, such that the first amplified signal including the amplified radiation signal and the amplified offset signal is output through an output terminal of the first amplifier, and wherein an input terminal of the second amplifier is grounded to receive the offset signal, and the offset signal applied to the input terminal of the second amplifier is amplified, such that the amplified offset signal is output through an output terminal of the second amplifier.