IO Driver Calibration Architecture for Stable Impedance Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing IO drivers face challenges in minimizing quantization error and impedance variation across process, voltage, and temperature (PVT) variations, often requiring large silicon area, long calibration times, or compromising high-speed operation.
Innovation Solution
The proposed solution involves a hybrid calibration method using a combination of thermometric and binary calibration codes to control the impedance of IO drivers, specifically utilizing a 1-bit thermometric portion and 4-bit binary portion, which reduces the number of calibration transistors and calibration time while maintaining control over quantization error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional calibration techniques are used to control driver impedance across PVT variations, then impedance stability is improved, but silicon area increases
Solution Approach 1:
The calibration code is segmented into two parts: a first calibration code for controlling a first set of calibration transistors and a second calibration code for controlling a second set of calibration transistors. This segmentation allows independent optimization of each calibration set, reducing the total number of transistors needed while maintaining impedance stability across PVT variations.
Solution Approach 2:
Instead of using a single comprehensive calibration code controlling all calibration transistors, the patent applies partial calibration actions through two separate calibration codes. Each code controls only a portion of the calibration transistors, which reduces the overall calibration complexity and transistor count while achieving sufficient impedance control.
2Manufacturing precision
If comprehensive calibration is applied to minimize quantization error, then manufacturing precision is improved, but calibration time increases
Solution Approach 1:
The calibration process is segmented into two independent stages using separate calibration codes. The first calibration code optimizes impedance for one set of transistors while the second calibration code optimizes another set. This segmentation enables parallel or sequential calibration without requiring full-system recalibration, significantly reducing total calibration time while maintaining precision.
Solution Approach 2:
The patent performs preliminary calibration actions by dividing the calibration task into two preparatory steps. Each calibration code performs its calibration function independently before final operation, allowing the system to achieve precise impedance control without requiring a single lengthy comprehensive calibration process.
3Stability of the object's composition
If large calibration transistors are used to control impedance variations, then impedance stability is improved, but device complexity increases
Solution Approach 1:
The calibration transistor network is divided into two groups, each controlled by a separate calibration code. This segmentation reduces the control complexity for each group while maintaining overall impedance stability. Each calibration code manages only a subset of transistors, simplifying the control logic and reducing device complexity compared to a single comprehensive calibration system.
Data Source
AI summary
A circuit or associated system or method comprises a first driver including a first transistor bank and a first resistor connected in series between a first predetermined voltage and an output pad, the first transistor bank including a first driver transistor and a plurality of first calibration transistors, wherein the plurality of first calibration transistors are respectively controlled based on a combination of bits of a first calibration code and on an output of at least one first logic gate.