Non-Overlapping Waveform Alignment Using Cross-Coupled Inverters
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Solution Overview
Problem
Conventional frequency conversion mixers face challenges in achieving optimal timing alignment and duty cycle balance for non-overlapping waveforms, particularly in pseudo-differential CMOS signal paths, leading to inefficiencies in local oscillator clock waveforms.
Innovation Solution
The implementation of cross-coupled inverters and NOR gates to generate and de-skew input waveforms, ensuring that output transitions occur only when other pulses are at logic '0', thereby improving the timing alignment and duty cycle balance of non-overlapping waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional frequency conversion mixers are used, then the system structure is simple, but the timing alignment and duty cycle balance of non-overlapping waveforms deteriorate
Solution Approach 1:
Cross-coupled inverters are introduced as intermediary components between the waveform synthesizer and NOR gates. These inverters receive non-overlapping waveforms and produce inverted waveforms with improved timing alignment by allowing output transitions only when other pulses are at logic '0', thereby mediating the timing skew without significantly increasing overall system complexity
Solution Approach 2:
The system is segmented into distinct functional blocks: waveform synthesizer, cross-coupled inverter stage, NOR gate stage, and mixer. This segmentation allows each block to be optimized independently for its specific function while maintaining overall system performance
2Manufacturing precision
If cross-coupled inverters and NOR gates are implemented, then timing alignment and duty cycle balance improve, but device complexity increases
Solution Approach 1:
Multiple functions are merged into the cross-coupled inverter-NOR gate structure: waveform inversion, timing alignment, duty cycle correction, and signal conditioning all occur within this integrated circuit block, reducing the need for separate components and minimizing overall device complexity despite the added functional capabilities
3Manufacturing precision
If conventional mixers are used, then the system is easier to operate, but timing skew propagates through the signal path
Solution Approach 1:
Timing alignment is performed in advance before the signals reach the mixer. The cross-coupled inverters and NOR gates pre-correct the timing skew and duty cycle errors in the non-overlapping waveforms, ensuring that by the time signals enter the mixer, they are already properly aligned and will not propagate skew through the signal path
Data Source
AI summary
Systems and methods for improving the timing alignment of non-overlapping waveforms are provided. In this regard, a representative system, among others, includes a waveform synthesizer that generates a plurality of input waveforms and inverters having inputs and outputs, wherein the inverters receive the input waveforms at the inputs of the inverters and invert the input waveforms, producing a plurality of inverted waveforms at the outputs of the inverters. The system also includes NOR gates having inputs and outputs, wherein the NOR gates receive the plurality of inverted waveforms at the inputs of the NOR gates and pass through one of the inverted waveforms at the outputs of the NOR gates.