Feedforward Differential Ring Divider for Low-Voltage Speed Limits
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Solution Overview
Problem
Existing ring oscillators suffer from limited speeds and phase mismatch issues, particularly in low voltage applications, due to their design requirements and propagation delays.
Innovation Solution
Configuring differential inverters used in ring-oscillator-based frequency dividers with feedforward elements, such as resistors, capacitors, transmission gates, and inverters, to cross couple inputs and outputs, thereby increasing the 3 dB bandwidth and reducing propagation delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional ring oscillators are used in low voltage applications, then power consumption is reduced, but oscillation frequency and speed are limited
Solution Approach 1:
Feedforward elements (resistors, capacitors, transmission gates) are introduced as intermediary components between the inputs and outputs of differential inverters in the ring oscillator. These intermediaries create additional signal paths that accelerate signal propagation without increasing power consumption, enabling the oscillator to achieve higher frequencies while maintaining low voltage operation.
2Loss of time
If feedforward elements are added to differential inverters, then propagation delay is reduced and bandwidth is increased, but device complexity increases
Solution Approach 1:
The ring oscillator is divided into multiple differential inverter stages, each independently enhanced with feedforward elements. This segmentation allows the complexity to be distributed and managed at the stage level rather than requiring complete redesign of the entire oscillator, making the complex circuit more manageable and implementable.
3Productivity
If ring oscillators operate at higher frequencies, then data rate capability is improved, but phase mismatch increases
Solution Approach 1:
The differential inverter configuration with feedforward elements provides inherent feedback mechanisms that stabilize the oscillation phases. The cross-coupled structure creates regenerative feedback that reinforces the desired phase relationships, maintaining phase accuracy even at high oscillation frequencies and enabling reliable high-data-rate operation.
Data Source
AI summary
Aspects of the subject disclosure may include, for example, a frequency divider, comprising a plurality of delay devices arranged to receive input clocks and generate output clocks, wherein one or more of the delay devices comprises a first transconductance element configured to receive a first input and provide a first output, a second transconductance element configured to receive a second input and provide a second output, a first feedforward transconductance element that cross couples the first input and the second output, and a second feedforward transconductance element that cross couples the second input and the first output. Other embodiments are disclosed.