Programmable Gain Amplifier Capacitor Switching for Stable Gain Changes
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Solution Overview
Problem
Programmable gain amplifiers (PGAs) experience instability due to disturbances generated during gain adjustments, which affects the stability of the circuit.
Innovation Solution
A PGA configuration using an operational amplifier and a capacitor array with multiple capacitors and switches, where the capacitors are selectively coupled to the input or ground terminal, allowing for flexible gain adjustments with minimal disturbance by maintaining the same gain value across different configurations through controlled switch states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If gain adjustment is performed by converting components inside the PGA, then the gain value can be changed, but disturbance is generated affecting the stability of the PGA
Solution Approach 1:
The patent changes the capacitance parameter of the capacitor array to achieve gain adjustment. By switching between different capacitance values (C1, C2, C3) in the capacitor array, the gain of the PGA is adjusted without changing other critical components, thereby minimizing disturbance and maintaining stability.
Solution Approach 2:
The capacitor array is segmented into multiple capacitors (first capacitor, second capacitor, third capacitor) that can be independently switched. This segmentation allows for discrete gain adjustments by selectively connecting different capacitor combinations, enabling precise control while maintaining overall system stability.
2Adaptability or versatility
If multiple capacitors are switched to adjust gain, then gain flexibility is improved, but circuit complexity increases
Solution Approach 1:
The patent merges the functionality of multiple capacitors into a single capacitor array structure. The first, second, and third capacitors are combined in parallel configuration, controlled by switch groups, to achieve multiple gain values through a unified structure rather than separate switching mechanisms.
Solution Approach 2:
The capacitor array serves multiple functions: it provides different capacitance values for gain adjustment, maintains stability during transitions, and enables flexible gain control. The same capacitor array structure is used across different gain configurations, making the system multi-functional without requiring additional components.
Data Source
AI summary
A program gain amplifier includes an operational amplifier and a capacitor array. The capacitor array includes a first, second, and third capacitors selectively coupled to the operational amplifier or ground according to a first, second, and third switches, respectively. The first, second, and third capacitors have a first, second, and third capacitance, respectively. The third capacitance equals a sum of the first and second capacitance. In a first configuration, the first and second switches are operated at a first conductive state, and the third switch is operated at a second conductive state. When converting to a second configuration from the first configuration, the third switch is operated at the first conductive state, and the first and second switches are operated at the second conductive state. The gain being provided to an input signal in the first and second configurations are the same.