Switchable Feedback Amplifier Circuit for Wide Dynamic Range
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Solution Overview
Problem
Conventional amplifier circuits for photodiodes require complex and large-scale structures to accommodate a wide dynamic range, leading to the use of expensive components and increased complexity due to the need for numerous high-resistance resistors and analog switches, which are costly and prone to leakage current errors.
Innovation Solution
An amplifier circuit with a simple structure that uses a voltage-dividing resistor circuit and feedback resistor circuit, where switches allow for resistance adjustments, reducing the number of high-resistance resistors and analog switches, thereby minimizing cost and complexity while maintaining a wide dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional amplifier circuits use a complex and large-scale circuit structure to accommodate wide dynamic range, then the dynamic range coverage is improved, but the device complexity and cost increase significantly
Solution Approach 1:
The feedback resistor circuit is segmented into multiple resistance elements (first feedback resistor circuit and second feedback resistor circuit) that can be selectively connected. This segmentation allows the circuit to achieve multiple gain ranges without requiring a completely different circuit structure for each range, thereby reducing overall complexity while maintaining wide dynamic range coverage
Solution Approach 2:
The circuit employs dynamic switching mechanisms (switches) that allow transition between different feedback resistor circuits based on input signal conditions. This dynamic reconfiguration enables the amplifier to adapt its gain characteristics in real-time, achieving wide dynamic range coverage without permanent complex circuitry for all possible gain states
2Adaptability or versatility
If conventional amplifier circuits use numerous high-resistance resistors and analog switches, then the dynamic range is improved, but the cost and leakage current errors increase
Solution Approach 1:
The feedback path is divided into multiple segmented resistor circuits with different resistance values. By selectively engaging only the necessary resistance segments for a given signal level, the circuit minimizes the number of high-resistance elements actively present, thereby reducing cumulative leakage current while maintaining the required dynamic range
Solution Approach 2:
The circuit extracts and removes unnecessary high-resistance resistors and analog switches from the active circuit path by using switching mechanisms to disconnect them when not needed. This extraction reduces leakage current sources while preserving the capability to access high resistance values when required for low-signal amplification
3Adaptability or versatility
If conventional amplifier circuits use a large number of expensive parts, then the dynamic range capability is improved, but the manufacturing cost increases
Solution Approach 1:
The feedback resistor circuits are designed with multi-functionality where the same physical resistor elements serve multiple gain ranges through different switching configurations. This universal design eliminates the need for separate expensive high-precision resistors for each gain stage, reducing component count and manufacturing cost while maintaining wide dynamic range capability
Solution Approach 2:
Instead of using multiple separate high-precision resistor networks for different gain ranges, the circuit uses a single set of feedback resistor circuits that are selectively activated. This copying approach where one physical implementation serves multiple functional purposes reduces the number of expensive parts needed while achieving the same dynamic range capability
Data Source
AI summary
An amplifier circuit includes: an operational amplifier that includes two input terminals and an output terminal; a voltage-dividing resistor circuit electrically connected to the output terminal and that includes a voltage-dividing terminal that outputs a potential obtained by voltage-dividing a potential of the output terminal and a feedback resistor circuit electrically connected to the voltage-dividing terminal and one of the two input terminals. The voltage-dividing resistor circuit includes a plurality of resistors that each include terminals and a switch. The plurality of resistors includes a first resistor and a second resistor. The first resistor includes a terminal that corresponds to the voltage-dividing terminal. The switch switches, from a first terminal of the first resistor to a second terminal of the second resistor, the terminal that corresponds to the voltage-dividing terminal.