ODT and OCD Impedance Control Using Adjustable Code Addition
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Solution Overview
Problem
Conventional semiconductor devices face challenges in precisely controlling impedance of on-die-termination (ODT) and off-chip-driver (OCD) circuits due to external factors like process, voltage, and temperature variations, and the inability to adjust fixed external resistance, which complicates impedance control at higher frequencies.
Innovation Solution
A semiconductor device with a control code generation unit and an addition unit that generates adjusted control codes by adding an adjustment code to the original control codes, allowing precise impedance adjustment of ODT and OCD circuits through transistor operations, enabling improved channel characteristics without modifying the calibration loop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration loops or code controllers are used to generate control codes for ODT and OCD circuits, then the impedance control is stable against PVT variations, but the precision of impedance control is insufficient for high-frequency operations
Solution Approach 1:
The control code is segmented into a base code from the calibration loop and an adjustment code added by the addition unit. This segmentation allows the stable base code to maintain PVT robustness while the adjustment code enhances precision for high-frequency operations.
Solution Approach 2:
The invention merges the output of the calibration loop with an adjustment code through the addition unit. This combination integrates the stability of the calibration loop with the precision enhancement from the adjustment code, resolving the contradiction between stability and precision.
2Measurement precision
If the calibration loop is modified to improve impedance control precision, then the precision increases, but the circuit complexity increases
Solution Approach 1:
The addition unit serves as an intermediary between the calibration loop and the ODT/OCD circuits. It adds the adjustment code to the calibration loop output without requiring modifications to the calibration loop itself, thus improving precision while minimizing circuit complexity increase.
Solution Approach 2:
The system dynamically adjusts the control code by adding an adjustment code to the base control code from the calibration loop. This dynamic adjustment mechanism enables precise impedance control without permanently increasing the static circuit complexity.
3Reliability
If external resistance is made adjustable to improve channel characteristics, then the channel electrical characteristics improve, but the device complexity increases
Solution Approach 1:
The invention replaces the need for adjustable external resistance with a digital adjustment code added to the control code. This substitutes a potential mechanical or external adjustment system with an internal digital processing approach, improving channel characteristics while avoiding increased device complexity.
Data Source
AI summary
Provided is a semiconductor device capable of controlling an on-die-termination (ODT) circuit and an off-chip-driver (OCD) circuit and a control method used by the semiconductor device. The semiconductor device includes a control code generation unit generating a control code in response to a control signal, an addition unit adding an adjustment code to the control code to produce an adjusted control code, and an ODT circuit, wherein an impedance of the ODT circuit is adjusted in response to the adjusted control code. The semiconductor device can adjust the control code more precisely by adding or subtracting the adjustment code to or from the control code. Accordingly, the impedance of an OCD circuit or ODT circuit can be adjusted more precisely.