I/O Circuit Phase Mixer for Fine Slew Rate Control
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Solution Overview
Problem
Current timing control methods in integrated circuit devices, such as semiconductor memory devices, offer only coarse control over slew rate, limiting the precision with which output signals can be synchronized with external clock signals, and require multiple inverter delays, which occupy valuable space and restrict fine resolution timing adjustments.
Innovation Solution
The implementation of phase mixer circuitry in adjustable driver circuits allows for fine resolution control of slew rate by configuring phase mixers with control words to adjust the timing of driver lines, enabling dynamic impedance control and reducing the need for external delay generation, thereby enhancing timing precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple inverter delays are used for timing control, then coarse timing adjustment is achieved, but device area increases and fine resolution control is restricted
Solution Approach 1:
The patent replaces the mechanical inverter delay system with a phase mixer circuit that uses signal phase manipulation. Instead of physically adding inverter stages that occupy silicon area, the invention uses a phase mixer to achieve timing control through phase adjustment of clock signals, thereby substituting a space-consuming mechanical approach with a more efficient signal processing approach.
Solution Approach 2:
The invention changes the control parameter from discrete inverter delay stages to continuous phase adjustment. By varying the phase of clock signals through the phase mixer, fine resolution timing control is achieved without being constrained by the discrete two-inverter delay minimum, thus improving timing precision without proportionally increasing device area.
2Measurement precision
If discrete inverter delays are used, then timing control is achieved, but only coarse resolution adjustments are possible
Solution Approach 1:
The patent replaces the discrete inverter delay mechanism with a phase mixer that manipulates signal phases. This substitution enables continuous or fine-grained timing adjustments rather than being limited to coarse discrete steps, thereby improving measurement precision while managing system complexity through a different architectural approach.
Solution Approach 2:
The phase mixer circuit serves multiple functions: it provides both the timing control function and the phase adjustment function in a single integrated component. This multi-functionality reduces overall device complexity compared to using separate inverter chains for timing and phase control, while enabling fine resolution adjustments.
3Manufacturing precision
If inverter delays are added to output path, then slew rate control is achieved, but logic level changes are required and area is consumed
Solution Approach 1:
The patent substitutes the traditional inverter-based slew rate control mechanism with a phase mixer approach. Instead of adding physical inverter stages that consume area and require logic level changes, the invention uses phase manipulation of clock signals to control the timing and slew rate of output drivers, achieving precise control with reduced area overhead.
Data Source
AI summary
An apparatus includes a terminal, a first plurality of driver lines, and a first phase mixer. The driver lines drive the terminal to a first logic state responsive to a first enable signal. The first phase mixer is coupled to a first one of the first plurality of driver lines. The first phase mixer is operable to receive the first enable signal and a first delayed enable signal derived from the first enable signal and generate a first signal on the first driver line having a first configurable delay with respect to the first enable signal by mixing the first enable signal and the first delayed enable signal.