Oscillation Amplitude Control Using Half-Cycle Signal Swapping
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Solution Overview
Problem
Integrated circuits face errors due to time-varying mismatches in component characteristics, such as flicker noise, which are not effectively corrected by existing calibration techniques.
Innovation Solution
The swapping-based amplitude control circuit inverts the sign of mismatches every half cycle of a periodic signal, using signal swappers, rectifiers, analog multiplexers, and selectable gain amplifiers to generate a control signal that adjusts the amplitude of oscillation signals, effectively eliminating static and time-varying mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration techniques are used to correct mismatches, then static mismatches can be corrected, but time-varying mismatches such as flicker noise and temperature gradients cannot be effectively corrected
Solution Approach 1:
The patent implements periodic swapping of signal paths at a frequency higher than the flicker noise frequency. The circuit alternates between two matched signal paths, with each path being active for one half-cycle. This periodic action allows the system to average out time-varying mismatches including flicker noise and temperature gradients, converting dynamic errors into a stable DC offset that can be removed by AC coupling.
Solution Approach 2:
The patent creates a duplicate copy of the signal path with matched components (second transistor, second current source, second switch) that mirrors the first path. By swapping between these two identical copies, the system can cancel out component mismatches through differential measurement and averaging, effectively eliminating the impact of manufacturing tolerances and environmental variations.
2Measurement precision
If signal swapping is implemented to correct time-varying mismatches, then flicker noise and dynamic errors are reduced, but circuit complexity increases
Solution Approach 1:
The patent implements periodic swapping of signal paths at a frequency higher than the flicker noise frequency. The circuit alternates between two matched signal paths, with each path being active for one half-cycle. This periodic action allows the system to average out time-varying mismatches including flicker noise and temperature gradients, converting dynamic errors into a stable DC offset that can be removed by AC coupling.
Solution Approach 2:
The patent combines two matched signal paths into a single differential architecture where both paths share common components (first switch, second switch, rectifiers, amplifiers). By merging the paths and using differential signaling, the circuit achieves mismatch cancellation while reducing the total component count compared to having completely separate paths.
3Manufacturing precision
If matched components are used to reduce manufacturing tolerances, then static mismatch errors are reduced, but mismatches still occur due to stress and temperature gradients
Solution Approach 1:
The patent creates a duplicate copy of the signal path with matched components (second transistor, second current source, second switch) that mirrors the first path. By swapping between these two identical copies, the system can cancel out component mismatches through differential measurement and averaging, effectively eliminating the impact of manufacturing tolerances and environmental variations.
Solution Approach 2:
The patent implements periodic swapping of signal paths at a frequency higher than the flicker noise frequency. The circuit alternates between two matched signal paths, with each path being active for one half-cycle. This periodic action allows the system to average out time-varying mismatches including flicker noise and temperature gradients, converting dynamic errors into a stable DC offset that can be removed by AC coupling.
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 reduces flicker noise and other dynamic errors, maintaining a stable oscillation signal amplitude by averaging out mismatches over cycles, improving the accuracy of distance measurement sensors like LC tank circuits.
Implementation Method 1
A first rectifier and a first analog multiplexer rectify the input oscillation signal to produce a first rectified signal
Data Source
AI summary
A circuit includes a first signal swapper including a first terminal coupled to a first current source, a second terminal coupled to a second current source, a third terminal coupled to a first current terminal of a first transistor, and a fourth terminal coupled to a third current terminal of a second transistor. The first signal swapper couples the first and second terminals to the third and fourth terminals responsive to a first control signal. First and second switches couple to a gate of the first transistor. The first switch receives the input oscillation signal and the second switch receives a first reference voltage. Third and fourth switches couple to a gate of the second transistor. The third switch receives the input oscillation signal and the fourth switch receives the first reference voltage. A second signal swapper couples to the first signal swapper and to the first and second transistors.