Folded Multi-Level Ramp Generator for Noise-Resistant Amplifiers
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Solution Overview
Problem
Amplifier systems that compare two ramps to an input signal are susceptible to common mode noise and experience information loss in the negative part of the input signal due to limited voltage range coverage.
Innovation Solution
A multi-level ramp generator providing three ramps, with the high and low ramps 'folded' relative to the middle ramp, each with different peak-to-peak magnitudes and common mode levels, captures information outside the voltage range of two-ramp systems, reducing common mode error and total harmonic distortion, and maintaining linearity by increasing the range of the overall ramp.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If two ramps are used for comparison, then the device complexity is reduced, but common mode noise susceptibility increases and information loss occurs in the negative part of the input signal
Solution Approach 1:
The single comparison function is segmented into three separate ramp comparisons instead of two. Each ramp (first, second, and third) operates at different frequency relationships (third ramp frequency is approximately double the first ramp frequency) and compares to different portions of the input signal, thereby distributing the comparison task across multiple independent channels that are less susceptible to common mode noise
Solution Approach 2:
The system transitions from a two-dimensional ramp comparison (two ramps) to a three-dimensional multi-level ramp comparison (three ramps with hierarchical frequency relationships). The first ramp operates at a base frequency, the second ramp at approximately double that frequency, and the third ramp at approximately double the second ramp's frequency, creating a hierarchical frequency structure that expands the voltage range coverage and captures signal information across multiple frequency dimensions
2Device complexity
If two ramps are used for comparison, then the voltage range coverage is limited, but the device complexity is reduced
Solution Approach 1:
The input signal range is segmented across three different ramp comparisons instead of two. Each ramp captures a specific portion of the signal dynamic range, with the first ramp capturing the base range, the second ramp capturing an extended range at double frequency, and the third ramp capturing the highest frequency range at quadruple frequency, thereby distributing the information capture across multiple segments without requiring a single complex high-range ramp
Solution Approach 2:
The system expands from two-dimensional voltage range coverage to three-dimensional multi-level voltage range coverage by introducing ramps at hierarchical frequency relationships. This creates overlapping voltage range coverage across three comparison channels, ensuring that the negative part of the input signal and other portions are captured by at least one ramp comparison, thereby eliminating information loss while maintaining manageable device complexity
Data Source
AI summary
A device includes a first ramp generator having a first ramp generator output configured to provide a first ramp, a second ramp generator having a second ramp generator output configured to provide a second ramp, and a third ramp generator having a third ramp generator output configured to provide a third ramp. The first ramp is a sawtooth voltage waveform having a first common mode voltage and a first peak-to-peak voltage. The second ramp is a sawtooth voltage waveform having a second common mode voltage and a second peak-to-peak voltage. The third ramp is a sawtooth voltage waveform having a third common mode voltage and a third peak-to-peak voltage. A frequency of the second ramp is approximately equal to a frequency of the third ramp, and the frequency of the third ramp is approximately double a frequency of the first ramp.