Cross-Coupled Frequency Divider for Low-Voltage Low-Noise Operation
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Solution Overview
Problem
Existing frequency divider circuits face challenges in reducing power consumption and size while maintaining low phase noise, especially in mobile devices where low voltage operation is required, often resulting in high power consumption or large area usage.
Innovation Solution
The design of a frequency divider circuit using resistive loading with cross-coupled transistors and separate biasing, allowing operation at low voltages (less than 1.3V) and providing a compact, low-noise, low-power solution that works off a regulated power supply, utilizing CMOS transistors to achieve the required voltage headroom and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional frequency divider circuits are used to maintain low phase noise, then phase noise performance is improved, but power consumption increases and area usage increases
Solution Approach 1:
The frequency divider circuit is divided into two separate cross-coupled latches operating at different frequencies. The first latch operates at the input frequency while the second latch operates at half the input frequency. This segmentation allows each latch to be optimized independently, reducing overall power consumption while maintaining low phase noise performance through separate biasing control.
Solution Approach 2:
The circuit employs separate biasing mechanisms for the two cross-coupled latches, allowing independent adjustment of bias currents. By optimizing bias parameters for each latch according to its operating frequency, the circuit achieves low phase noise at both frequencies while minimizing power consumption. The bias voltages are adjusted to ensure proper operation at the reduced supply voltage of less than 1.3 volts.
2Object-affected harmful factors
If conventional frequency divider circuits are used to maintain low phase noise, then phase noise performance is improved, but area usage increases
Solution Approach 1:
The circuit merges the functionality of two frequency-dividing latches into a single integrated structure where the output of the first latch feeds directly into the second latch. This combining approach reduces the total area required compared to implementing separate frequency divider circuits, while still achieving low phase noise performance through the coordinated operation of both latches with separate biasing.
3Use of energy by moving object
If supply voltage is reduced to less than 1.3 volts for low-power operation, then power consumption is reduced, but circuit operation becomes difficult
Solution Approach 1:
The circuit is designed with adjusted transistor dimensions and biasing parameters specifically optimized for low-voltage operation below 1.3 volts. The cross-coupled latches use carefully selected width-to-length ratios and bias currents that ensure proper switching operation at the reduced supply voltage, maintaining reliability while achieving low-power consumption.
Solution Approach 2:
The circuit employs dynamic biasing where the bias voltages for the two latches are independently controlled to adapt to the low supply voltage conditions. This dynamic adjustment of bias parameters ensures that each latch operates reliably at its optimal point despite the constrained voltage headroom, maintaining circuit functionality and reducing power consumption simultaneously.
Data Source
AI summary
A frequency divider circuit is described. The frequency divider circuit includes a first cross-coupling. The first cross-coupling includes a first cross-coupled transistor with a first gate. The first gate is separately biased. The first cross-coupling also includes a second cross-coupled transistor with a second gate. The second gate is separately biased. The first gate is coupled to the second cross-coupled transistor and the second gate is coupled to the first cross-coupled transistor.