AFE Integrator Auto-Ranging With Charge Dump for High Dynamic Range
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Solution Overview
Problem
The existing amplifier in analog front-end (AFE) circuits for computed tomography imaging systems faces challenges in achieving high dynamic range without increasing power consumption or circuit area, as the dynamic range is limited by capacitor values and supply voltage, and increasing these components leads to undesirable increases in power or size.
Innovation Solution
The proposed solution involves an integrator with a trigger circuit and charge dump circuit that modifies the configuration when the input signal exceeds a threshold, allowing for auto-ranging by discharging the capacitor through a charge dump circuit, thereby increasing the dynamic range without increasing power or area, and reconfiguring the amplifier between miller and RC compensation modes to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitor values and supply voltage are increased to achieve high dynamic range, then dynamic range is improved, but power consumption and circuit area increase
Solution Approach 1:
The amplifier dynamically switches between two operating modes (standard gain mode and charge dump mode) based on the input signal level. The trigger circuit monitors the integrator output and activates the charge dump circuit when the signal exceeds a threshold, allowing the system to adapt its behavior to different signal conditions and achieve extended dynamic range without proportionally increasing power consumption
Solution Approach 2:
The system changes the operational parameters of the amplifier by switching between different gain configurations. In charge dump mode, the feedback path is modified to enable controlled discharge of the integrator capacitor, effectively changing the amplifier's transfer function and allowing it to handle both small and large signal levels within the same hardware configuration
2Measurement precision
If capacitor values and supply voltage are increased to achieve high dynamic range, then dynamic range is improved, but circuit area increases
Solution Approach 1:
The same amplifier circuit performs multiple functions by switching between standard operation and charge dump modes. The charge dump circuit shares the integrator capacitor and other components with the standard path, allowing one piece of hardware to serve dual purposes: normal signal amplification and extended dynamic range handling through controlled charge discharge
Solution Approach 2:
The amplifier dynamically switches between two operating modes (standard gain mode and charge dump mode) based on the input signal level. The trigger circuit monitors the integrator output and activates the charge dump circuit when the signal exceeds a threshold, allowing the system to adapt its behavior to different signal conditions and achieve extended dynamic range without proportionally increasing power consumption
3Adaptability or versatility
If the amplifier uses fixed configuration, then circuit complexity is low, but adaptability to different signal levels is limited
Solution Approach 1:
The trigger circuit provides feedback monitoring of the integrator output signal level and uses this information to control the switching of the charge dump circuit. This feedback mechanism allows the amplifier to automatically adapt its configuration based on the actual signal conditions, enabling it to handle both small and large signals effectively without manual intervention
Solution Approach 2:
The amplifier automatically adjusts its own configuration through the trigger circuit and charge dump mechanism. When the integrator output exceeds the threshold, the system self-corrects by activating the charge dump path, which resets the integrator and prevents saturation, allowing continuous operation across a wide dynamic range without external control
Data Source
AI summary
In described examples, a circuit includes an integrator. The integrator generates a first signal responsive to an input signal. A trigger circuit is coupled to the integrator and receives the first signal. A charge dump circuit is coupled to the integrator and the trigger circuit. The trigger circuit modifies configuration of the charge dump circuit and the integrator when the first signal is greater than a first threshold.