Digital Phase Mixer Break-Before-Make Timing for Wide Frequency Range
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Solution Overview
Problem
Conventional phase locked loops (PLLs) and delay locked loops (DLLs) with digital phase mixers face issues with 'fighting' conditions due to timing gaps between early and late input signals, leading to short circuit currents and reduced reliability, power dissipation, and limited frequency range.
Innovation Solution
The implementation of a one-bit digital phase mixer with distributed break-before-make drivers, feedback loops, and early turn-off, along with separate pull-up and pull-down paths, controls the slew rates and duty cycle of clock signals to prevent 'fighting' conditions and enhance frequency performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional phase mixers are used with timing gaps between early and late input signals, then the phase mixing function is achieved, but short circuit currents occur due to 'fighting' conditions
Solution Approach 1:
The patent applies preliminary action by implementing break-before-make drivers that proactively open the switch connected to the earlier signal before closing the switch for the later signal. This anticipatory timing control prevents the harmful overlap condition before it can occur, eliminating the fighting condition that causes short circuit currents while maintaining the phase mixing function.
2Speed
If conventional phase mixers operate at high frequencies, then speed performance is improved, but fighting conditions increase leading to higher power dissipation
Solution Approach 1:
The patent implements feedback mechanisms through controlled timing relationships where the break-before-make driver timing is adjusted based on the frequency of operation. The system dynamically adapts the timing gap between opening the first switch and closing the second switch to match the operating frequency, preventing fighting conditions across a wide frequency range while minimizing power dissipation.
3Adaptability or versatility
If the frequency range is expanded, then adaptability is improved, but fighting conditions become more difficult to control
Solution Approach 1:
The patent applies dynamics by making the timing characteristics of the break-before-make drivers adaptive to the operating frequency. The timing gap between switching operations dynamically adjusts with frequency changes, allowing the system to maintain optimal performance across a wide frequency range without requiring complex external timing control circuitry.
Data Source
AI summary
The present disclosure is directed to a unit phase mixer in combination with an input buffer. The unit phase mixer has a pull-up path for pulling an output terminal up to a first voltage. The pull-up path has a first transistor responsive to a first enable signal and a series connected second transistor responsive to a first clock signal. The unit phase mixer has a pull-down path for pulling the output terminal down to a second voltage. The pull-down path has a third transistor responsive to a second clock signal and a series connected fourth transistor responsive to a second enable signal. The input buffer skews the first and second clock signals by different amounts to enable a break-before-make method of operation so that the first voltage is not connected to the second voltage. The unit phase mixer can be used as a building block in more complex mixers which may include the ability to weight the input clocks as well as providing feed-forward paths for certain of the signals. Because of the rules governing abstract, this abstract should not be used to construe the claims.