On-Die Termination DAC with Variable Resistors for Wider Tuning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional digital-to-analog converters and on-die termination apparatuses have limited control over transistor resistance values, leading to a narrow adjustment range and increased chip area due to the need for multiple driver legs.
Innovation Solution
Incorporating variable resistors in the driver legs of digital-to-analog converters, allowing for fine control of resistance values through level-changed codes and variable voltages, enabling broader adjustment ranges without increasing the number of driver legs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If transistors in driver legs are controlled only in full turn-on/off operations using conventional digital codes, then the circuit structure is simple, but the resistance values cannot be finely controlled and are limited to a narrow adjustment range
Solution Approach 1:
The patent applies dynamics by transitioning from static full turn-on/off control to dynamic partial turn-on control of transistors. By controlling the gate voltage to achieve partial conduction states rather than binary on/off, the transistor resistance can be continuously adjusted, enabling fine control of resistance values in driver legs for on-die termination.
Solution Approach 2:
The patent changes the control parameter from binary digital codes (0 or 1) to multi-level digital codes that represent different gate voltage levels. This parameter change allows the transistor to operate in different conduction regions, achieving continuous resistance adjustment and expanding the resistance value adjustment range.
2Adaptability or versatility
If the number of driver legs is increased to enlarge the adjustment range of resistance values, then the resistance adjustment range is enlarged, but the chip area increases
Solution Approach 1:
By implementing dynamic resistance control within each driver leg through partial turn-on operation, the patent enables continuous resistance adjustment without needing multiple discrete driver legs. This dynamic control approach allows a single driver leg to provide a range of resistance values, reducing the total number of driver legs required and thereby reducing chip area.
Solution Approach 2:
The patent makes each driver leg multi-functional by enabling it to provide multiple resistance values through partial turn-on control. Instead of requiring separate driver legs for different resistance values, a single driver leg can assume multiple resistance states, increasing adaptability while reducing the number of components and chip area.
3Manufacturing precision
If conventional digital codes at power supply or ground voltage levels are used, then the control logic is simple, but the transistors cannot be finely controlled and resistance values are limited
Solution Approach 1:
The patent changes the voltage level parameter of control codes from binary levels (0V or VDD) to intermediate voltage levels that correspond to partial conduction states. By introducing multiple voltage levels in the control signal, the transistor gate can be controlled to achieve different conduction degrees, enabling fine control of resistance values while maintaining digital code control simplicity.
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 approach allows for precise control of resistance values and expanded adjustment ranges, reducing the number of driver legs required and enhancing area efficiency in semiconductor devices.
Implementation Method 1
a driver leg 10 to be connected to external resistor (ZQ). When an enable signal 'EN' is activated to a high level, a digital code PCODE (i=0 to N) is input to a gate of the transistor (M10) in the driver leg 10
Implementation Method 2
An analog voltage signal 'Vpcode' is output by dividing a power supply voltage (VDDQ) in proportion to the voltage division ratio which is conducted by resistance elements consisting of the resistor (R10) and the fully turned-on transistor (M10) in the driver leg 10 and the external resistor (ZQ)
Data Source
AI summary
A digital-to-analogue converting circuit includes a driver leg having a plurality of resistance elements between a power supply voltage terminal and a ground voltage terminal, wherein at least one of the plurality of resistance elements is a variable resistor, and a code level changing unit for outputting a level-changed code to a control terminal of the variable resistor based on an activation of a digital code, wherein the level-changed code is produced by converting a level of the digital code.