Frequency response mismatch calibration in 2-channel time-interleaved oscilloscopes.

Area of Science:

• Electrical Engineering
• Signal Processing
• Data Acquisition Systems

Background:

• Time-interleaved (TI) structures increase sampling rates in high-speed data acquisition but suffer from frequency response mismatches (FRMs) between sub-channels.
• Parasitic parameters in printed circuit board (PCB) level TI systems exacerbate FRMs, degrading overall system performance more than in TI analog-to-digital converters (TIADCs).

Purpose of the Study:

• To research and develop an effective FRM calibration method for 2-channel TI acquisition systems.
• To address systems with a larger mismatch range and utilize a general model for channel frequency responses.

Main Methods:

• Developed a calibration structure by analyzing a digital TI model to reconstruct mismatches in the time domain.
• Transformed arbitrary frequency response filter design into a three-stage cascaded filter group realization.
• Proposed an oscilloscope prototype for experimental verification.

Main Results:

• Demonstrated the effectiveness of the proposed calibration method despite significant FRMs and a general frequency response model.
• Achieved significant suppression of magnitude and phase response mismatch ranges.
• Improved the spurious-free dynamic range by 16.26 dB in the prototype after calibration.

Conclusions:

• The developed digital calibration method is effective for TI systems with substantial FRMs and general frequency responses.
• The proposed filter design approach enables the realization of arbitrary frequency responses in practical systems.
• The calibration significantly enhances the dynamic performance of TI data acquisition systems.