Two-Stage Phase Blender for Precise Multi-Phase Clock Signals
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Solution Overview
Problem
Conventional multi-phase oscillators face limitations in generating precise and stable multi-phase signals due to the use of full swing signals, which leads to imprecise phase interpolation and unstable electrical characteristics when additional capacitors are added for loading.
Innovation Solution
A two-staged phase-blender design using differential OP phase-blender circuits and inverter phase-blender circuits to generate multi-phase clock signals from non-full swing signals, eliminating the need for additional capacitors and ensuring stable electronic characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If full swing signals are used for phase interpolation, then the circuit structure is simple, but the phase precision is imprecise
Solution Approach 1:
The patent transforms full swing signals into non-full swing signals by controlling the operating points of transistors M3 and M4. This parameter change in signal amplitude enables precise phase interpolation without requiring complex circuit structures or additional capacitors, thus resolving the contradiction between circuit simplicity and phase precision.
2Measurement precision
If capacitors are added for loading to improve phase precision, then the phase precision improves, but the manufacturing stability deteriorates
Solution Approach 1:
The patent extracts and eliminates the capacitors from the circuit structure. Instead of using capacitors for loading, the invention uses the intrinsic capacitance of transistors M3 and M4 to achieve non-full swing signals. This removal of external capacitors eliminates manufacturing variability while maintaining phase precision.
Solution Approach 2:
The transistors M3 and M4 provide their own loading effect through their intrinsic capacitance, eliminating the need for external capacitors. This self-service approach ensures that the phase precision is maintained without introducing manufacturing stability issues associated with external capacitor loading.
3Speed
If the number of inverter stages is decreased to increase maximum frequency, then the maximum frequency increases, but the ability to generate odd-number multi-phase signals is limited
Solution Approach 1:
The patent segments the phase generation function into two independent parts: the ring oscillator generates base frequency signals, and the phase blender separately generates the required phase angles. This segmentation allows the oscillator to operate at maximum frequency with fewer stages while the phase blender provides the necessary multi-phase capability, resolving the contradiction between speed and versatility.
Data Source
AI summary
An apparatus for generating multi-phase clock signals with a ring oscillator is provided, including a first stage phase-blender module and a second stage phase-blender module. The first stage phase-blender module further includes a plurality of differential OP phase-blender circuits. Each differential blender circuit has two signal inputs, and an output signal whose phase is an interpolation of the two input signals. The second stage phase blender module includes a plurality of inverter phase-blender circuits. Each inverter phase-blender circuit receives two output signals from the first stage phase-blender module as inputs, and outputs a clock signal with the interpolated phase of the two output signals of the first stage phase-blender module.