Dynamic Gain Control Circuit for Low Power Radiation Detection
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Solution Overview
Problem
Conventional radiation detectors face challenges in effectively detecting radiation due to high power consumption and limited dynamic range, especially in high-counting conditions like medical applications, where a wideband interface circuit with low power consumption is required to match the dynamic range of analog-to-digital converters.
Innovation Solution
A circuit incorporating a shunt and a gain controller that adjusts the gain of input current by shunting it into multiple current paths, allowing for dynamic gain control and reducing power consumption while maintaining wideband input capabilities, implemented in an integrated circuit using CMOS technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an operational amplifier with large gain bandwidth is used to configure a wideband circuit, then the bandwidth is improved, but power consumption increases
Solution Approach 1:
The circuit is divided into multiple stages: a first operational amplifier for gain control and a second operational amplifier for output buffering. This segmentation allows each stage to be optimized independently, enabling wideband operation without requiring a single high-power amplifier to handle the entire bandwidth requirement.
Solution Approach 2:
The circuit employs dynamic gain control through a gain control unit that adjusts the gain of the first operational amplifier based on input signal conditions. This dynamic adjustment allows the circuit to maintain wideband performance while consuming less power by adapting the amplification level to the actual signal requirements rather than operating at maximum gain continuously.
2Adaptability or versatility
If gain control is applied to maintain constant bandwidth, then adaptability is improved, but device complexity increases
Solution Approach 1:
The gain control unit is integrated directly into the first operational amplifier stage, merging the gain control functionality with the amplification function. This integration reduces overall circuit complexity compared to having separate gain control circuits, while still providing adaptable gain adjustment to maintain constant bandwidth across varying input conditions.
Solution Approach 2:
The first operational amplifier serves multiple functions: it provides both the primary amplification and the gain control functionality. This multi-functionality reduces the need for additional dedicated components, thereby reducing device complexity while maintaining the adaptability to control gain and preserve bandwidth.
3Productivity
If multiple detectors are disposed in limited space for X-ray CT, then detection capability is improved, but space requirements increase
Solution Approach 1:
The circuit implements a nested structure where the gain control unit is embedded within the operational amplifier circuitry, and multiple such units can be integrated on a single chip. This nesting allows multiple detector channels to be packed into a compact footprint, improving detection capability while minimizing the space required for the detector array in X-ray CT systems.
Data Source
AI summary
According to an embodiment, a circuit includes a shunt and a controller. The shunt shunts input current into a plurality of current paths. The controller controls a gain of current inputted to the shunt by combining the current that is shunted into the current paths by the shunt in combination corresponding to a first signal from the outside or changing a shunt ratio with which the shunt shunts the current into the current paths corresponding to the first signal.