ASK Receiver Self-Calibration for PWM Offset Drift
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Solution Overview
Problem
Inter-chip data communication faces challenges in accurately recovering PWM signals due to offset voltage issues between amplifier inputs, particularly during temperature changes and start-up/standby phases, which existing solutions fail to adequately address without increasing power consumption or requiring external components.
Innovation Solution
A self-calibration technique for offset compensation in ASK receivers using a dynamic analog approach, integrated within CMOS technology, that dynamically adjusts for temperature-induced offset drifts without external components, enabling automatic and accurate calibration during all operational phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If offset compensation is implemented using existing solutions, then offset voltage issues are partially addressed, but power consumption increases and external components are required
Solution Approach 1:
The receiver circuit performs self-calibration by automatically detecting and compensating for offset voltages in the amplifier without requiring external calibration equipment or additional power management components. The circuit uses its own internal resources to measure and correct the offset, making the system self-sufficient and avoiding increased power consumption.
Solution Approach 2:
The offset compensation function is extracted as a separate calibration routine that operates independently from the main signal processing path. By isolating the offset measurement and correction operations, the system can perform calibration without affecting the power consumption of the primary receiver functions.
2Reliability
If manual or preliminary offset setting is used, then offset compensation is achieved, but the process becomes complex and requires external components
Solution Approach 1:
The receiver circuit autonomously performs offset calibration by detecting the offset voltage and adjusting the amplifier accordingly. The system uses internal control logic to execute the calibration sequence, eliminating the need for external calibration equipment and manual intervention, thereby reducing device complexity while maintaining high compensation accuracy.
Solution Approach 2:
The offset calibration is performed as a preliminary step during the receiver initialization or standby phase, before normal signal processing begins. This preliminary action ensures that the amplifier is properly compensated before actual communication operations, simplifying the overall system operation.
3Measurement precision
If static offset compensation is implemented, then initial offset is corrected, but temperature-induced offset drift cannot be compensated
Solution Approach 1:
The offset compensation system transitions from a static correction approach to a dynamic calibration process that can be repeatedly executed during different operational phases including standby and active communication. This dynamic approach allows the system to continuously adapt to temperature changes and maintain accurate offset compensation across varying thermal conditions.
Solution Approach 2:
The offset calibration is performed periodically during standby phases or at predetermined intervals during operation, allowing the system to re-compensate for offset drift caused by temperature variations. This periodic recalibration ensures that the amplifier remains accurately compensated throughout different thermal environments.
Data Source
AI summary
An envelope detector receives a modulated signal and a differential stage coupled to the detector produces a replica modulated signal compared to produce a PWM-modulated signal having on and off times. A first switch is actuated to short-circuit the input to the envelope detector. A second switch is actuated to feed back to a storage capacitor a signal indicative of the difference between inputs to the differential stage. A third switch is actuated to short-circuit an input to the comparator. Logic circuitry activates the switched to implement offset compensation where: the first, second and third switches are actuated in the absence of the PWM-modulated signal during start-up and standby phases; and the first, second and third switches are actuated during off times of the PWM-modulated signal in a working phase alternating with the start-up/standby phases.