CN104345328A - Radiation detection circuit - Google Patents

Abstract

The present invention provides a radiation detection circuit, comprising: a first PMOS transistor for sensing radiation to be measured; a first amplifier connected to the first PMOS transistor; a second PMOS transistor not to sense radiation to be measured; and a second a second amplifier connected to the PMOS transistor; and a comparison module, used to compare the outputs of the first amplifier and the second amplifier, and amplify the difference for output. The invention simplifies the structure of the radiation detection circuit and greatly reduces the power consumption compared with the prior art.

Description

radiation detection circuit

technical field

The invention relates to the technical field of semiconductors, in particular to a radiation detection circuit. the

Background technique

In space, many electronic devices will be exposed to certain radiation environments. In order to ensure the reliability of these electronic devices, it is necessary to detect the total dose of radiation. Because once the total radiation dose exceeds a certain amount, it will cause the failure of the electronic system. the

PMOS total dose radiation detectors mainly include radiation-sensitive field-effect transistors made by a specific process. The MOSFET threshold voltage drifts due to oxide traps and interface trap charges generated after irradiation. By calibrating the relationship between the threshold voltage drift and the radiation dose, the threshold voltage drift is measured to obtain the radiation dose. Generally speaking, after NMOS is irradiated, oxide trap charges cause its threshold voltage to shift negatively, but interface charges cause its threshold voltage to shift positively; both oxide trap charges and interface charges generated after PMOS radiation make its threshold voltage Negative drift, so most of the total dose radiation detection circuits generally use PMOS field effect transistors as the total dose radiation detector. the

From the above principles, it can be known that the circuit can be designed according to the change of the threshold voltage of the pMOS transistor, so that it can reflect the size of the total dose radiation environment. As shown in FIG. 1 , it is a schematic diagram of a detection circuit in the prior art. The readout circuit is composed of four main modules, which can convert an analog signal into a digital signal for output. Therefore this detection circuit is too complex to satisfy some digital automation systems. But in general application, AD conversion is not needed. the

Therefore, it is hoped to propose a relatively simple pMOS total dose radiation monitoring circuit that can be applied in the laboratory. the

Contents of the invention

An object of the present invention is to provide a radiation detection circuit with simpler structure and lower power consumption. the

The present invention provides a radiation detection circuit, comprising: a first PMOS transistor for sensing radiation to be measured; a first amplifier connected to the first PMOS transistor; a second PMOS transistor not to sense radiation to be measured; and a second amplifier connected to the second PMOS transistor; and a comparison module, used to compare the outputs of the first amplifier and the second amplifier, and amplify and output the difference. the

Optionally, the first amplifier is an operational amplifier, the source of the first PMOS transistor is connected to the power supply voltage, the drain is connected to the common-mode input terminal of the first amplifier, and the gate is connected to the differential-mode input terminal of the first amplifier, The output of the first amplifier is connected to the common mode input terminal of the comparison module. the

Optionally, there is a first ballast resistor between the gate of the first PMOS transistor and the differential mode input terminal of the first amplifier. the

Optionally, the second amplifier is an operational amplifier, the source of the second PMOS transistor is connected to the power supply voltage, the drain is connected to the differential mode input terminal of the second amplifier, and the gate is connected to the common mode input terminal of the second amplifier, The output of the second amplifier is connected to the differential mode input terminal of the comparison module. the

Optionally, there is a second ballast resistor between the gate of the second PMOS transistor and the common-mode input terminal of the second amplifier. the

Optionally, configurations of the first PMOS transistor and the second PMOS transistor are completely the same, and configurations of the first amplifier and the second amplifier are completely the same. the

Optionally, the first and second PMOS transistors work in a saturation region. the

Optionally, the comparison module includes a third amplifier whose output signal reflects the magnitude of the radiation to be measured. the

Optionally, the radiation detection circuit further includes a steady current module, and the steady current module is configured to provide equal steady currents to drains of the first PMOS transistor and the drains of the second PMOS transistor. the

Optionally, the current stabilization module includes: a constant voltage source, the anode of which is connected to the common-mode input terminal of the first amplifier and the differential-mode input terminal of the second amplifier, and the cathode is grounded; a third current stabilization resistor, one end of which is connected to One end of the positive pole of the constant voltage source is grounded; one end of the fourth stabilizing resistor is connected to the positive pole of the constant voltage source, and the other end is grounded; the resistance values of the third stabilizing resistor and the fourth stabilizing resistor are equal. the

The radiation detection circuit in the prior art adopts AD conversion. The inventors of the present invention have found that accurate radiation detection can also be achieved by using analog devices without AD conversion, which has a simpler structure and lower power consumption. The present invention utilizes the characteristic that the oxide trap charge and interface charge generated after PMOS radiation both cause the threshold voltage to drift negatively, and uses the relationship between the threshold voltage drift and the radiation dose to sense the radiation to be measured with the first PMOS transistor. Due to the influence of the radiation to be measured, the output of the first PMOS transistor is offset and amplified by the first amplifier. While the second PMOS transistor is not subjected to radiation, its output is also amplified by the second amplifier. The signals amplified by the first amplifier and the second amplifier are compared by the comparison module, and the output can reflect the offset of the output voltage of the first PMOS transistor caused by the influence of radiation, and the offset reflects the amount of radiation. In this way, the purpose of detecting the radiation to be measured can still be achieved by using a simple analog circuit, and the effect of detecting radiation with simpler radiation and lower power consumption is achieved. the

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings. the

Fig. 1 is the radiation detection circuit schematic diagram of prior art;

Fig. 2 is a structural diagram of a radiation detection circuit according to an embodiment of the present invention. the

Detailed ways

Embodiments of the present invention are described in detail below. the

Examples of the described embodiments are shown in the drawings, wherein like or similar reference numerals designate like or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention. The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, components and arrangements of specific examples are described below. Of course, they are only examples and are not intended to limit the invention. the

The invention provides a PMOS radiation detection circuit based on an operational amplifier. Next, the radiation detection circuit shown in FIG. 2 will be described in detail through an embodiment of the present invention. As shown in Figure 2, the radiation detection circuit provided by the present invention includes the following structures:

A first PMOS transistor M1 for sensing radiation to be measured;

A first amplifier A1 connected to the first PMOS transistor M1;

The second PMOS transistor M2 that does not sense the radiation to be measured;

a second amplifier A2 connected to the second PMOS transistor M2; and

The comparison module is used to compare the outputs of the first amplifier A1 and the second amplifier A2, and amplify and output the difference. the

Optionally, the first amplifier A1 is an operational amplifier, the source of the first PMOS transistor M1 is connected to the power supply voltage, the drain is connected to the common-mode input terminal of the first amplifier A1, and the gate is connected to the differential voltage of the first amplifier A1. mode input terminal, the output of the first amplifier A1 is connected to the common mode input terminal of the comparison module. But the first amplifier can also use other amplifiers, as long as it can amplify the signal output by the first PMOS transistor. Since the signal output by the first PMOS is too small to be directly measured or entered into the comparison module for comparison, it must pass through the first amplifier. The use of operational amplifiers is beneficial to further simplifying the structure and further reducing power consumption. the

Optionally, there is a first current stabilizing resistor R3 between the gate of the first PMOS transistor M1 and the differential mode input terminal of the first amplifier A1. It helps to stabilize the current between the gate of the first PMOS transistor M1 and the differential input terminal of the first amplifier A1. the

Preferably, the second amplifier A2 is an operational amplifier, the source of the second PMOS transistor M2 is connected to the power supply voltage, the drain is connected to the differential mode input terminal of the second amplifier A2, and the gate is connected to the common mode of the second amplifier A2 The input terminal, the output of the second amplifier A2 is connected to the differential mode input terminal of the comparison module. But the second amplifier can also use other amplifiers, as long as it can amplify the signal output by the second PMOS transistor. Since the signal output by the second PMOS is too small to be directly measured or entered into the comparison module for comparison, it must pass through the second amplifier. The use of operational amplifiers is beneficial to further simplifying the structure and further reducing power consumption. the

Optionally, there is a second current stabilizing resistor R4 between the gate of the second PMOS transistor M2 and the common-mode input terminal of the second amplifier A2. It works similarly to R3. the

Wherein, the configurations of the first PMOS transistor M1 and the second PMOS transistor M2 are completely the same, and the configurations of the first amplifier A1 and the second amplifier A2 are completely the same. the

Wherein, the first and second PMOS transistors M1 and M2 work in a saturation region. the

Optionally, the comparison module includes a third amplifier A3, whose output signal reflects the size of the radiation to be measured. However, other comparison modules, such as built-up comparison circuits, may also be used. the

Wherein, the radiation detection circuit further includes a steady current module, and the steady current module is used for providing equal steady currents to the drains of the first PMOS transistor M1 and the second PMOS transistor M2. the

Wherein, the steady flow module includes:

A constant voltage source V, the positive pole of which is connected to the common-mode input terminal of the first amplifier A1 and the differential-mode input terminal of the second amplifier A2, and the negative pole is grounded;

The third steady current resistor R1, one end of which is connected to the positive pole of the constant voltage source, and one end is grounded;

The fourth stabilizing resistor R2, one end of which is connected to the positive pole of the constant voltage source, and one end of which is grounded;

The resistance values of the third steady current resistor R1 and the fourth steady current resistor R2 are equal. the

The detailed structure is introduced in detail below. the

The radiation-sensitive detector is mainly a radiation-sensitive field-effect transistor made by a specific process. The MOSFET threshold voltage drifts due to oxide traps and interface trap charges generated after irradiation. By calibrating the relationship between the threshold voltage drift and the radiation dose, the threshold voltage drift is measured to obtain the radiation dose. Generally speaking, after NMOS is irradiated, oxide trap charges cause its threshold voltage to shift negatively, but interface charges cause its threshold voltage to shift positively; both oxide trap charges and interface charges generated after PMOS radiation make its threshold voltage Negative drift, which is why PMOS field effect transistors are generally used as total dose radiation detectors. the

After radiation, the threshold voltage of the PMOS in the saturation region has a negative drift, according to the current formula in the saturation region of the PMOS transistor:

According to the current formula in the saturation region of the PMOS transistor:

${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; D.</span>}}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&mu;</span>}}_{\mathrm{<span\; class="notranslate">\; P</span>}}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; OX</span>}}\frac{\mathrm{<span\; class="notranslate">\; W</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; GS</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; TH</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$

Among them, _ID represents the source-drain current of the MOS tube, μ _P represents the mobility of holes in the PMOS, W and L represent the width and length of the MOS tube respectively, C _OX represents the gate oxide capacitance, V _GS represents the gate-source voltage, and V _TH is the threshold voltage.

M1 and M2 are radiation-sensitive PMOS transistors, where M1 is used as a radiation detector to receive radiation signals, and M2 is used as a reference transistor, placed in a radiation-free environment to provide a comparison signal for M1, and the size and process of M1 and M2 transistors are equal. In order to make the circuit structure symmetrical, here M2 also selects a radiation-sensitive transistor. the

It can be seen that the resistance values of the third and fourth steady-state resistors R1 and R2 are equal, and the currents flowing through R1 and R2 are equal. It can be known from Kirchhoff’s current law that the currents flowing through the first and second PMOS transistors M1 and M2 Also equal. After receiving the radiation, the threshold voltage of M1 changes. Due to the stabilizing effect of the constant current source on the current, the current in M1 remains unchanged. Therefore, the gate voltage of M1 must change accordingly and pass through the first stabilizing resistor R3 It is transmitted to the differential mode input terminal of the first amplifier A1, and the voltage difference between the gate and the drain of M1 is amplified through A1. At the same time, transistor M2 does not receive radiation, and its current and voltage remain unchanged, which are equal to the current and voltage values of M1 before radiation, and A2 takes the reference voltage difference between the gate and drain of M2 before radiation Amplify and output. the

The outputs of the radiation sensing module and the reference module are respectively connected to the common-mode and differential-mode input ends of the third amplifier A3, the difference between them is amplified by A3 and output, and finally the amplified voltage is obtained. Based on this, the total dose of radiation can be calculated. Finally, by measuring the change of the final amplified voltage, and according to the magnification of the circuit design, the change amount of the threshold voltage of the radiation-sensitive PMOS transistor can be calculated, and finally the total dose of radiation can be calculated. the

Those skilled in the art can select the required first, second, and third amplifiers A1, A2, and A3 as required, and design relevant parameters to set a certain amplification factor for amplifying and outputting the differential signal. the

Compared with the prior art, the present invention can use a constant current source to convert the current generated by the radiation-sensitive PMOS tube into the change of the potential at both ends of the source and the drain, and use it as the differential input of the differential amplifier circuit to realize the single output caused by radiation. Direct and small threshold voltage changes are transformed into larger bidirectional voltage changes, which makes it easy to detect the total radiation dose. Compared with the prior art, it is not only convenient and easy to operate, but also has a simple circuit structure, no redundant power consumption components, and greatly reduces power consumption. the

Although the present invention and its advantages have been described in detail in conjunction with specific embodiments, it should be understood that various changes, substitutions and modifications can be made to these embodiments without departing from the spirit of the present invention and the scope of protection defined by the appended claims. Revise. For other examples, it should be readily understood by those of ordinary skill in the art that the order of the process steps can be varied while remaining within the scope of the present invention. the

In addition, the scope of application of the present invention is not limited to the process, mechanism, manufacture, material composition, means, method and steps of the specific embodiments described in the specification. From the disclosure of the present invention, those of ordinary skill in the art will easily understand that for the processes, mechanisms, manufacturing, material compositions, means, methods or steps that currently exist or will be developed in the future, they are implemented in accordance with the present invention Corresponding embodiments described which function substantially the same or achieve substantially the same results may be applied in accordance with the present invention. Therefore, the appended claims of the present invention are intended to include these processes, mechanisms, manufacture, material compositions, means, methods or steps within their protection scope. the

Claims (10)

1. a radiation detection circuit, comprising:

For sensing first PMOS transistor (M1) of radiation to be measured;

The first amplifier (A1) be connected with the first PMOS transistor (M1);

Do not sense second PMOS transistor (M2) of radiation to be measured;

The second amplifier (A2) be connected with the second PMOS transistor (M2); And

Comparison module, for the output of the first amplifier (A1) and the second amplifier (A2) being compared, and carries out amplification output by its difference.

2. radiation detection circuit according to claim 1, it is characterized in that, first amplifier (A1) is operational amplifier, the source electrode of described first PMOS transistor (M1) connects supply voltage, the common mode input end of drain electrode connection first amplifier (A1), grid connects the difference-mode input end of described first amplifier (A1), and the output of described first amplifier (A1) connects the common mode input end of described comparison module.

3. radiation detection circuit according to claim 2, is characterized in that, there is the first ballast resistance (R3) between the grid of described first PMOS transistor (M1) and the difference-mode input end of the first amplifier (A1).

4. radiation detection circuit according to claim 1, it is characterized in that, second amplifier (A2) is operational amplifier, the source electrode of described second PMOS transistor (M2) connects supply voltage, the difference-mode input end of drain electrode connection second amplifier (A2), grid connects the common mode input end of described second amplifier (A2), and the output of described second amplifier (A2) connects the difference-mode input end of described comparison module.

5. radiation detection circuit according to claim 4, is characterized in that, there is the second ballast resistance (R4) between the grid of described second PMOS transistor (M2) and the common mode input end of the second amplifier (A2).

6. the radiation detection circuit according to any one in claim 1 to 5, it is characterized in that, first PMOS transistor (M1) configures identical with the second PMOS transistor (M2), and the first amplifier (A1) is identical with the configuration of the second amplifier (A2).

7. radiation detection circuit according to claim 1, is characterized in that, described first, second PMOS transistor (M1, M2) works in saturation region.

8. radiation detection circuit according to claim 1, is characterized in that, described comparison module comprises the 3rd amplifier (A3), the size of its output signal reflection radiation to be measured.

9. radiation detection circuit according to claim 1, it is characterized in that, described radiation detection circuit also comprises current stabilization module, and described current stabilization module is used for being that the drain electrode of the first PMOS transistor (M1) and the second PMOS transistor (M2) provides equal steady current.

10. radiation detection circuit according to claim 9, is characterized in that, described current stabilization module comprises:

Constant voltage source (V), its positive pole connects the common mode input end of described first amplifier (A1) and the difference-mode input end of the second amplifier (A2), minus earth;

3rd ballast resistance (R1), the positive pole of one termination constant voltage source, one end ground connection;

4th ballast resistance (R2), the positive pole of one termination constant voltage source, one end ground connection;

Described 3rd ballast resistance (R1) is equal with the 4th ballast resistance (R2) resistance.