Termination Circuit With Individual Resistor Trimming for Impedance Matching
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Solution Overview
Problem
Semiconductor devices face challenges in high-speed operation due to increased external noise and signal distortion caused by impedance mismatch, which affects signal integrity and can lead to setup/hold failures and misjudgments.
Innovation Solution
A semiconductor device with a termination circuit that includes individually trimmable resistor groups, a calibration circuit for generating impedance control codes, and an individual trimming controller to adjust pull-up and pull-down termination blocks based on test mode signals and group selection signals, ensuring precise impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a parallel termination circuit is used to improve signal integrity, then impedance matching is improved, but the circuit complexity increases due to multiple resistor groups requiring individual trimming
Solution Approach 1:
The termination circuit is divided into multiple resistor groups (first pull-up resistor group, second pull-up resistor group, first pull-down resistor group, second pull-down resistor group) that can be individually trimmed. This segmentation allows precise impedance matching for different signal conditions while maintaining manageable circuit complexity through modular design.
Solution Approach 2:
The termination circuit employs dynamic trimming control where each resistor group can be independently adjusted based on signal characteristics. The individual trimming capability allows the circuit to adapt impedance values dynamically, optimizing signal integrity across varying operating conditions without requiring a completely complex redesign.
2Speed
If the swing width of signals is decreased to minimize transmission time, then speed is improved, but signal reflection and noise susceptibility increase
Solution Approach 1:
The invention changes the impedance parameter of the termination circuit to match the characteristic impedance of the transmission line. By individually trimming resistor groups to achieve precise impedance matching, the circuit maintains signal integrity even with decreased swing widths, preventing reflection and noise susceptibility while preserving high-speed transmission capabilities.
3Reliability
If impedance matching is achieved through individual trimming of resistor groups, then signal integrity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The termination circuit incorporates preliminary trimming mechanisms where resistor groups are pre-configured with close-to-target impedance values during manufacturing. The individual trimming capability then allows for fine-adjustment to achieve precise impedance matching, reducing the burden on manufacturing precision while ensuring optimal signal integrity.
Solution Approach 2:
The circuit includes feedback mechanisms that monitor impedance matching conditions and adjust individual resistor groups accordingly. This feedback-based trimming approach compensates for manufacturing variations, achieving precise impedance matching without requiring extremely high manufacturing precision for each resistor component.
Data Source
AI summary
A semiconductor device includes a calibration circuit suitable for generating impedance control codes based on an external resistor coupled to a calibration pad; an individual trimming controller suitable for generating a plurality of individual trimming signals based on test mode signals and group selection signals; and a termination circuit including a plurality of resistor groups, coupled in parallel to a data pad, that are trimmed as a group based on the impedance control codes, each of the plurality of resistor groups being individually trimmed based on a corresponding signal among the plurality of individual trimming signals.