Asymmetrical Regenerative Frequency Divider for Wide Locking Range
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Solution Overview
Problem
Existing regenerative frequency dividers in CMOS technology face challenges such as low transconductance of MOS devices, significant voltage headroom consumption, and limited bandwidth, making it difficult to achieve high-speed operation and power efficiency, especially in RFIC applications.
Innovation Solution
The implementation of an asymmetrical regenerative frequency divider with an in-phase mixer circuit and a phase-shifted mixer circuit, where the phase-shifted mixer circuit has smaller switching devices than the in-phase mixer circuit, reduces power dissipation and improves overall efficiency while maintaining a wide locking range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a double-balanced mixer implementation is used to achieve a wide locking range, then the locking range is improved, but power dissipation increases
Solution Approach 1:
The mixer circuit is segmented into two separate mixer circuits: an in-phase mixer circuit and a phase-shifted mixer circuit. This segmentation allows independent optimization of each circuit's power consumption while maintaining the overall wide locking range performance through their combined operation.
Solution Approach 2:
The switching devices in the phase-shifted mixer circuit are designed with different (smaller) dimensions compared to those in the in-phase mixer circuit. This local quality differentiation enables reduced power dissipation in the phase-shifted path while preserving the necessary locking range through the in-phase path.
2Ease of manufacture
If MOS devices are used in CMOS technology, then integration is improved, but transconductance decreases requiring large voltage drop
Solution Approach 1:
The circuit utilizes periodic switching action at the resonant frequency of the LC tank to achieve frequency division. The periodic switching of the MOS devices in the mixer circuits generates the necessary mixing products without requiring large continuous voltage drops, leveraging the resonant build-up of voltage across the LC tank.
Solution Approach 2:
The invention changes the operating parameters by using an asymmetrical configuration where the phase-shifted mixer circuit has different device dimensions compared to the in-phase circuit. This parameter change optimizes the trade-off between transconductance and power consumption in CMOS technology.
3Reliability
If source followers are used to buffer signals, then signal isolation is improved, but voltage headroom is consumed and bandwidth is limited
Solution Approach 1:
The invention extracts and eliminates the source follower buffering stage from the signal path. Instead of using source followers for signal isolation, the design relies on the inherent isolation properties of the double-balanced mixer configuration and the high impedance of the LC tank, thereby removing the bandwidth and headroom limitations imposed by source followers.
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
This approach enhances the power efficiency of regenerative frequency dividers and allows for a wider locking range within a given power budget, as demonstrated by benchmarked performance data showing reduced current consumption compared to conventional injection-locked frequency dividers.
Implementation Method 1
mixing the input and output signals produces sum and difference frequencies of ωin/2 and 3ωin/2 at the output of the mixer
Implementation Method 2
employing an LC tank as the load of the regenerative frequency divider
Data Source
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AI summary
A regenerative frequency divider comprising an in-phase mixer circuit and a phase-shifted mixer circuit. At least one switching device of the in-phase mixer circuit is of a smaller scale than a corresponding switching device of the transconductance component of the in-phase mixer circuit. In some examples, at least one switching device within an input switching stage of the regenerative frequency divider forming part of the phase-shifted mixer circuit is of a smaller scale than a respective corresponding switching device within the input switching stage forming part of the in- phase mixer circuit. In some further examples, all switching devices within the phase-shifted mixer circuit are of a small scale than respective corresponding switching devices within the in-phase mixer circuit.