Calibration of Time-Interleaved Errors in Digital Real-Time Oscilloscopes

Area of Science:

• Electrical Engineering
• Signal Processing
• Measurement Science

Background:

• Time-interleaved analog-to-digital converters (TIADCs) are crucial for high-speed digital real-time oscilloscopes (DRTOs).
• Channel mismatch errors in TIADCs degrade measurement accuracy.
• Existing calibration methods often rely on complex additional filtering stages.

Purpose of the Study:

• To propose a novel channel mismatch calibration method for DRTO applications.
• To develop a calibration technique that simplifies error correction in TIADCs.
• To enhance the accuracy and efficiency of DRTO measurements.

Main Methods:

• Derivation of linear equations using Fourier transforms of separated signals from TIADCs.
• Calibration of TIADC errors through matrix inversion.
• Development of a transfer function measurement method for commercial DRTOs.

Main Results:

• The proposed method calibrates TIADC errors effectively via matrix inversion, eliminating the need for additional filters.
• Calibration accuracy is primarily limited by post-TIADC noise, outperforming filter-dependent methods.
• Validation using two-tone signals on commercial DRTOs demonstrated a significant reduction in spurious frequencies.

Conclusions:

• The proposed matrix inversion method offers a simpler and more accurate approach to channel mismatch calibration in DRTOs.
• This technique enhances the performance of TIADCs by minimizing calibration-induced errors.
• The transfer function measurement method is suitable for practical application in commercially available DRTOs.