Ring Oscillator Injection Circuit for Wide-Locking-Range Prescalers
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Solution Overview
Problem
Current prescaler designs in phase-locked loop (PLL) circuits for radio frequency (RF) systems face challenges with high power consumption and limited frequency operating range, particularly in current mode logic (CML) prescalers, while injection locked frequency dividers (ILFD) offer lower power consumption but at the cost of reduced frequency range.
Innovation Solution
The implementation of a ring oscillator with multiple stages in a ring configuration, utilizing direct and tail injection circuits in each stage to enhance the locking range, achieving low power consumption and a wide frequency range, with power consumption less than 10 mW and a locking range of at least 30%, by injecting an oscillator signal through direct and tail injection paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If CML based prescalers are used, then frequency operating range is maintained, but power consumption increases significantly
Solution Approach 1:
The prescaler is divided into multiple independent stages (first stage, second stage, third stage) where each stage can be independently controlled and optimized. This segmentation allows the circuit to achieve wide frequency range while maintaining low power consumption by selectively activating only necessary stages for different frequency ranges.
Solution Approach 2:
The prescaler implements dynamic switching between different operating modes and stages based on the input frequency. The circuit adapts its configuration in real-time to maintain optimal performance across a wide frequency range while minimizing power consumption for each operating condition.
2Adaptability or versatility
If ILFD based prescalers are used, then power consumption is reduced, but frequency operating range decreases
Solution Approach 1:
The patent combines multiple ILFD-based stages with different frequency division ratios and characteristics into a single integrated prescaler circuit. By merging these stages and implementing intelligent switching between them, the circuit achieves an extended frequency operating range while maintaining the low power consumption advantages of ILFD architecture.
3Adaptability or versatility
If multiple injection circuits are added to enhance locking range, then frequency range increases, but circuit complexity increases
Solution Approach 1:
The injection circuit is segmented into multiple independent injection paths (first direct injection circuit, second direct injection circuit, tail injection circuit) that can be selectively activated. This segmentation extends the locking range by providing multiple injection points while managing complexity through modular design and selective activation.
Solution Approach 2:
Each injection circuit stage is designed to serve multiple functions: frequency division, phase locking, and frequency range extension. The universal design of the multi-stage architecture allows the same basic circuit topology to handle different frequency ranges and injection requirements, reducing overall system complexity despite the extended functionality.
Data Source
AI summary
In accordance with an embodiment, a ring oscillator includes a plurality of stages coupled in a ring configuration, where stage of the plurality of stages has an input node coupled to an output node of a previous stage of the plurality of stages. Each stage of the plurality of stages includes: a ring oscillator transistor having a control node coupled to the input node, and a load path coupled to the output node; a direct injection circuit having a load path coupled between the control node of the ring oscillator transistor and the output node, and a control node coupled to a first oscillator input node; and a tail injection circuit having a load path coupled between the output node and a first power supply node, and a control node coupled to a second oscillator input node.