Transimpedance Amplifier Feedback Circuit for Peaking Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional transimpedance amplifiers face challenges in achieving high gain and wide band characteristics while suppressing peaking and ground impedance issues, particularly due to parasitic inductance caused by bonding and contact holes in feedback circuits.
Innovation Solution
A transimpedance amplifier with a feedback circuit having two or more extreme frequencies, featuring a flat filter characteristic up to the smallest extreme frequency and decreasing thereafter, is designed with multiple resistances in parallel and at least one capacitance between dividing points, allowing for suppression of peaking without significant gain reduction in high-frequency regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the capacitance in the parallel connection circuit is reduced to broaden the band, then the bandwidth is improved, but peaking occurs causing group delay deterioration
Solution Approach 1:
The feedback circuit is segmented into multiple parallel connection circuits (first, second, and third circuits) with different capacitance values. Each circuit handles a specific frequency range, with the first circuit having the largest capacitance for low frequencies, the second having intermediate capacitance, and the third having the smallest capacitance for high frequencies. This segmentation allows the amplifier to achieve wide bandwidth without peaking in any single frequency region.
Solution Approach 2:
Each parallel connection circuit is designed with locally optimized capacitance values tailored to specific frequency ranges. The first circuit uses capacitance C1 for low-frequency stabilization, the second uses C2 for mid-frequency response, and the third uses C3 for high-frequency extension. This local quality approach ensures that each segment contributes optimally to its designated frequency band without causing peaking.
2Speed
If the resistance in the parallel connection circuit is reduced to broaden the band, then the bandwidth is improved, but the gain is reduced
Solution Approach 1:
The feedback resistance is segmented across multiple parallel connection circuits, each with resistance values optimized for specific frequency ranges. The first circuit has resistance R1, the second has R2, and the third has R3, where each resistance-capacitance pair works together to provide frequency-dependent feedback. This segmentation enables bandwidth extension while maintaining gain through the combined effect of all circuits.
Solution Approach 2:
Multiple parallel connection circuits are merged in parallel within the feedback path of the transimpedance amplifier. The combined feedback effect of all circuits (with their respective resistance and capacitance values) provides both wide bandwidth and maintained gain. The merging of these circuits creates a composite feedback characteristic that achieves both objectives simultaneously.
3Device complexity
If conventional feedback circuits are used, then the circuit is simple, but parasitic ground inductance from bonding and contact holes degrades performance
Solution Approach 1:
The invention extracts and eliminates the problematic ground connection from the feedback circuit by using a two-terminal configuration. By removing the ground reference point, parasitic ground inductance from bonding and contact holes is eliminated. The feedback circuit becomes a floating two-terminal network that is immune to ground impedance effects, maintaining performance without requiring complex compensation techniques.
Solution Approach 2:
Instead of the conventional three-terminal feedback circuit connected to ground, the invention inverts the approach by using a two-terminal floating feedback circuit without ground connection. This inversion of the grounding concept eliminates parasitic ground inductance while maintaining the feedback function, achieving high performance with a simpler configuration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration achieves a constant gain in high-frequency regions, suppressing peaking and enabling a wider band without reducing gain, while being immune to ground inductance effects.
Implementation Method 1
a feedback circuit having two or more extreme frequencies, the feedback circuit having a filter characteristic which is flat with respect to frequencies in a frequency region not more than a smallest extreme frequency among the extreme frequencies, is flat with respect to frequencies in a frequency region not less than a largest extreme frequency among the extreme frequencies, and has at least one negative inclination portion with respect to frequencies in a frequency region between the smallest and largest extreme frequencies
Data Source
AI summary
The present invention solves characteristic deterioration caused by peaking and a ground inductance, and provides a transimpedance amplifier capable of achieving a higher gain and a wider band. For this purpose, the transimpedance amplifier is configured to include a feedback circuit having two or more extreme frequencies and having a filter characteristic which is flat with respect to frequencies in a frequency region not more than a smallest extreme frequency among the extreme frequencies, which is flat with respect to frequencies in a frequency region not less than a largest extreme frequency among the extreme frequencies, and which has at least one negative inclination portion with respect to frequencies in a frequency region between the smallest and largest extreme frequencies.