Signal-Swapping Amplitude Control for Flicker Noise Cancellation
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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 gain amplifiers to generate a control signal that adjusts the oscillation signal amplitude, thereby reducing flicker noise and dynamic errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration techniques are used to correct mismatches, then static mismatch errors are reduced, but time-varying mismatches such as flicker noise and temperature gradients cannot be 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 errors like flicker noise and temperature gradients, correcting them dynamically rather than statically.
Solution Approach 2:
The patent inverts the conventional approach by swapping the roles of two matched signal paths periodically. Instead of using a single path and trying to correct its errors, the system uses two paths and inverts which one is active, causing time-varying errors to cancel out when averaged over complete cycles. This inversion strategy transforms a static correction limitation into a dynamic solution.
2Reliability
If signal swapping is implemented to correct time-varying mismatches, then flicker noise and dynamic errors are reduced, but circuit complexity increases due to additional components
Solution Approach 1:
The patent divides the signal path into two separate but matched segments, each with its own amplifier and associated components. By segmenting the circuit into two parallel paths that are periodically swapped, the system achieves error correction through diversity while maintaining functional simplicity within each segment. The segmentation allows independent optimization of each path while benefiting from their combined error-cancellation capability.
3Measurement precision
If multiple matched components are used in signal paths, then static mismatch errors are reduced, but manufacturing precision requirements and cost increase
Solution Approach 1:
The patent creates a copy of the signal path using two matched amplifiers and associated components. By copying the circuit topology and using identical component designs, the system achieves matching without requiring ultra-precise manufacturing tolerances. The copying approach allows standard manufacturing processes to produce matched components, as the matching is achieved through design symmetry rather than extreme precision control.
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.