# US 2023/0057535 A1 · Radiation detector capable of noise handling

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- Number: US 2023/0057535 A1
- Document ID: US20230057535A1
- Status: Published application
- Kind: A1
- Application number: 17/981,774
- Filed: 2022-11-07
- Published: 2023-02-23
- Earliest claimed: 2017-10-26
- Assignees: Shenzhen Xpectvision Technology Co., Ltd.
- Applicants: Shenzhen Xpectvision Technology Co., Ltd.
- Inventors: Peiyan CAO; Yurun LIU
- Web page: https://patentgrep.com/patent/US20230057535A1

## CPC

- G01T 1/248: {Silicon photomultipliers [SiPM], e.g. an avalanche photodiode [APD] array on a common Si substrate}
- A61B 6/032: {Transmission computed tomography [CT]}
- G01T 1/1603: {with a combination of at least two different types of detectors}
- G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

Disclosed herein is a radiation detector, comprising: an avalanche photodiode (APD) with a first side coupled to an electrode and configured to work in a linear mode; a capacitor module electrically connected to the electrode and comprising a capacitor, wherein the capacitor module is configured to collect charge carriers from the electrode onto the capacitor; a current sourcing module in parallel to the capacitor, the current sourcing module configured to compensate for a leakage current in the APD and comprising a current source and a modulator; wherein the current source is configured to output a first electrical current and a second electrical current; wherein the modulator is configured to control a ratio of a duration at which the current source outputs the first electrical current to a duration at which the current source outputs the second electrical current.

## Claims

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### Claim 32

A radiation detector, comprising:
an avalanche photodiode (APD) with a first side coupled to an electrode and configured to work in a linear mode;
a first voltage comparator configured to compare a voltage of the electrode to a first threshold;
a second voltage comparator configured to compare the voltage to a second threshold;
a counter configured to register a number of photons absorbed by the APD;
a controller;
wherein the controller is configured to start a time delay from a time at which the first voltage comparator determines that an absolute value of the voltage equals or exceeds an absolute value of the first threshold;
wherein the controller is configured to activate the second voltage comparator during the time delay;
wherein the controller is configured to cause the number registered by the counter to increase by one, if the second voltage comparator determines that an absolute value of the voltage equals or exceeds an absolute value of the second threshold.

### Claim 33 (depends on 32)

The radiation detector of claim 32, wherein the controller is configured to activate the second voltage comparator at a beginning or expiration of the time delay.

### Claim 34 (depends on 32)

The radiation detector of claim 32, further comprising a voltmeter, wherein the controller is configured to cause the voltmeter to measure the voltage upon expiration of the time delay.

### Claim 35 (depends on 34)

The radiation detector of claim 34, wherein the controller is configured to determine a photon energy based on a value of the voltage measured upon expiration of the time delay.

### Claim 36 (depends on 32)

The radiation detector of claim 32, wherein the controller is configured to connect the electrode to an electrical ground.

### Claim 37 (depends on 32)

The radiation detector of claim 32, wherein a rate of change of the voltage is substantially zero at expiration of the time delay.

### Claim 38 (depends on 32)

The radiation detector of claim 32, wherein a rate of change of the voltage is substantially non-zero at expiration of the time delay.

### Claim 39 (depends on 32)

The radiation detector of claim 32, further comprising:
a capacitor module electrically connected to the electrode and comprising a capacitor, wherein the capacitor module is configured to collect charge carriers from the electrode onto the capacitor;
a current sourcing module in parallel to the capacitor, the current sourcing module configured to compensate for a leakage current in the APD and comprising a current source and a modulator;
wherein the current source is configured to output a first electrical current and a second electrical current;
wherein the modulator is configured to control a ratio of a duration at which the current source outputs the first electrical current to a duration at which the current source outputs the second electrical current.

### Claim 40 (depends on 39)

The radiation detector of claim 39, wherein the current sourcing module is adjustable.

### Claim 41 (depends on 39)

The radiation detector of claim 39, wherein the current sourcing module is configured to divert the leakage current in the APD through the current sourcing module.

### Claim 42 (depends on 39)

The radiation detector of claim 39, wherein the first electrical current and the second electrical current are different in their magnitude, direction, or both.

### Claim 43 (depends on 39)

The radiation detector of claim 39, wherein least one of the first electrical current and the second electrical current is at least an order of magnitude larger than the leakage current in the APD.

### Claim 44 (depends on 39)

The radiation detector of claim 39, wherein the leakage current in the APD is from 1 pA to 1000 pA.

### Claim 45 (depends on 39)

The radiation detector of claim 39, wherein the modulator comprises a processor or a memory.

### Claim 46 (depends on 39)

The radiation detector of claim 39, wherein the modulator comprises a switch.

### Claim 47 (depends on 39)

The radiation detector of claim 39, wherein the radiation comprises soft X-ray, ultraviolet (UV) light or extreme ultraviolet (EUV) light.

### Claim 48 (depends on 39)

The radiation detector of claim 39, wherein the current source comprises a current mirror.

### Claim 49 (depends on 48)

The radiation detector of claim 48, wherein the modulator is located on an input stage of the current mirror.

### Claim 50 (depends on 49)

The radiation detector of claim 49, wherein the modulator comprises a current source configured to output electrical current at alternating magnitudes.

### Claim 51 (depends on 49)

The radiation detector of claim 49, wherein the modulator comprises a current source configured to output two magnitudes of electrical current with adjustable ratio of durations.

### Claim 52 (depends on 48)

The radiation detector of claim 48, wherein the modulator is located on an output stage of the current mirror.

### Claim 53 (depends on 52)

The radiation detector of claim 52, wherein the modulator comprises a switch configured to controllably connect the current sourcing module to and to controllably disconnect it from the capacitor.

### Claim 54 (depends on 52)

The radiation detector of claim 52, wherein the radiation detector comprises an array of APDs.

### Claim 55 (depends on 32)

A system comprising the radiation detector of claim 32 and an X-ray source.

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