RF Demodulator Self-Calibration for Accurate Gain Compensation
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Solution Overview
Problem
Conventional RF-demodulators face inaccuracies in gain calibration due to transistor mismatch between test structures and actual demodulator circuits, and inability to calibrate gain deviations caused by resistors, leading to process and temperature variations.
Innovation Solution
An RF-demodulator with an integrated calibration circuitry that applies a calibration input signal and senses the resulting output signal to derive the gain of the mixing and amplification stage, allowing for precise calibration without external test structures and accounting for resistor deviations, by switching between different configurations based on the derived gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a separate test structure is used to measure transistor DC transconductance, then the measurement process is simplified, but the calibration accuracy deteriorates due to transistor mismatch between test structure and demodulator circuit
Solution Approach 1:
The patent merges the test structure with the actual demodulator circuit by integrating calibration circuitry directly into the demodulator. This eliminates the separate test structure approach and uses the actual demodulator components (including resistors and transistors) for self-calibration, thereby resolving the mismatch problem while maintaining measurement simplicity.
2Ease of operation
If conventional separate test structure calibration is used, then the calibration process is straightforward, but the ability to calibrate resistor-induced gain deviations is lost
Solution Approach 1:
The demodulator performs self-calibration by using its own internal components (resistors, transistors, and mixing stage) to measure and correct its own gain deviations. The calibration circuitry is integrated within the demodulator, allowing it to autonomously characterize and compensate for process and temperature variations without external testing equipment.
3Measurement precision
If integrated calibration circuitry is implemented within the demodulator, then calibration accuracy improves by using actual demodulator components, but device complexity increases
Solution Approach 1:
The calibration circuitry is designed to perform multiple functions: it generates calibration signals, measures gain deviations, and controls switching between different configurations of the mixing and amplification stage. This multi-functionality reduces the need for separate dedicated components for each calibration function, thereby managing complexity while achieving high calibration accuracy.
4Device complexity
If the mixing and amplification stage operates in fixed configuration, then the circuit design is simpler, but the ability to compensate for process and temperature variations is reduced
Solution Approach 1:
The mixing and amplification stage is designed with switchable configurations that can be dynamically adjusted based on calibration results. The calibration circuitry determines the optimal configuration by measuring gain deviations and controlling switches to reconfigure the mixing and amplification stage, enabling the circuit to adapt to process and temperature variations while maintaining manageable complexity.
Data Source
AI summary
An RF-demodulator includes an RF-input, a demodulator output, a mixing and amplification stage coupled between the RF-input and the demodulator output, and a calibration circuitry. The calibration circuitry is configured to apply a calibration input signal at the RF-input and sense a resulting calibration output signal at the demodulator output to derive a gain of the mixing and amplification stage based on the relationship between the calibration output signal and the calibration input signal.