Per-Pin Reference Voltage Generator for DRAM Voltage Droop
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Solution Overview
Problem
In computing systems, DRAM access times are slowed by voltage droop, leading to increased memory latency and power consumption, particularly in mixed voltage systems, where cache misses and voltage offsets across pins hinder performance.
Innovation Solution
A reference voltage generator system that uses a resistor ladder with a current controller to dynamically adjust reference voltages for each pin, allowing for independent generation of logic high and low voltages without relying on operational amplifiers, thus reducing power consumption and improving calibration speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reference voltage generator is implemented for each pin to compensate for voltage droop and offset, then voltage stability and noise immunity are improved, but on-die area consumption increases
Solution Approach 1:
The patent divides the interface into groups of pins (e.g., 2-4 pins per group) and implements a reference voltage generator for each group rather than for every individual pin. This segmentation approach maintains voltage stability compensation capability while reducing the total number of reference voltage generators needed, thereby decreasing on-die area consumption.
Solution Approach 2:
The reference voltage generator is designed to serve multiple pins within a group simultaneously. By making the generator multi-functional and capable of compensating for voltage droop and offset across several pins, the patent reduces the overall quantity of generators required, thus reducing on-die area while maintaining reliability.
2Reliability
If traditional voltage compensation methods using operational amplifiers are used, then voltage stability is improved, but power consumption increases
Solution Approach 1:
The patent replaces expensive and high-power operational amplifiers with a simpler, lower-power reference voltage generator circuit. This substitution uses a more energy-efficient architecture that achieves voltage stability without the high power consumption characteristics of traditional op-amp-based solutions, making it suitable for battery-powered mobile devices.
3Reliability
If operational amplifiers are used for voltage generation, then voltage stability is improved, but calibration speed decreases
Solution Approach 1:
The patent extracts and removes the operational amplifier component from the voltage generation circuitry, replacing it with a dedicated reference voltage generator. This extraction eliminates the settling time bottleneck associated with op-amps, enabling faster calibration speed while maintaining the necessary voltage stability through the alternative generator architecture.
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
The system enhances DRAM access speed by stabilizing voltage levels across pins, reducing power consumption, and improving noise immunity, while maintaining a compact on-die solution that does not quickly drain mobile device batteries.
Implementation Method 1
a resistor ladder 170. In an embodiment, the reference voltage generator 150 uses a single tap 176 of the resistor ladder 170 for generating a default reference voltage 180
Implementation Method 2
the reference voltage generator 150 injects or draws current with a current controller 152 to adjust a voltage level of the default reference voltage 180
Data Source
AI summary
Systems, apparatuses, and methods for generating a reference voltage are described. In various embodiments, an interface between a memory and a processor uses a reference voltage generator to generate a reference voltage for a single pin or a small group of pins. The generator generates a default reference voltage from a first tap in a resistor ladder, injects current with a current controller into a second tap of the resistor ladder when the generator receives an indication to generate a larger reference voltage, and draws current from a third tap of the resistor ladder when the generator receives an indication to generate a smaller reference voltage. The generator also generates a high threshold voltage independent of a low threshold voltage after calibration.