Center-tapped on-chip transformer having low alternating-current impedance

By introducing a MOM capacitor and a current return path into the on-chip transformer of the center tap, the high impedance problem at the center tap is solved, the linearity and common-mode rejection capability of the circuit are improved, and the performance of the millimeter-wave circuit is optimized.

WO2025001270A1PCT designated stage expired Publication Date: 2025-01-02JIASHAN FUDAN RESEARCH INSTITUTE +1
View PDF 6 Cites 0 Cited by

Patent Information

Application Number
PCT/CN2024/079887
Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
Priority Date
2023-06-30
Filing Date
2024-03-04
Publication Date
2025-01-02

AI Technical Summary

Technical Problem

In the existing technology, the routing scheme of center tap introduces a large parasitic inductance, resulting in excessively high impedance at the center tap, which affects the performance of millimeter-wave circuits, especially causing nonlinearity and common-mode signal interference at specific frequency points. Furthermore, the impedance is unbalanced when powered on one side, affecting the circuit's third-order intermodulation point and common-mode rejection capability.

Method used

The design employs a low AC impedance center-tapped on-chip transformer. By introducing an MOM capacitor between the center tap and the primary coil, a current return path is formed, reducing parasitic inductance. In single-sided power supply, an additional capacitor is added to maintain impedance balance.

Benefits of technology

It significantly reduces the impedance at the center tap, decreases parasitic inductance, improves the linearity and common-mode rejection capability of the circuit, optimizes the third-order intermodulation point performance, saves PAD resources, and enhances the performance of millimeter-wave circuits.

✦ Generated by Eureka AI based on patent content.

Smart Images

  • Figure CN2024079887_02012025_PF_FP_ABST
    Figure CN2024079887_02012025_PF_FP_ABST
Patent Text Reader

Abstract

Provided in the present invention is a center-tapped on-chip transformer having low alternating-current impedance. The center-tapped on-chip transformer comprises a center tap, a primary coil and a secondary coil, wherein the secondary coil and the primary coil are spaced apart from each other by means of a dielectric layer; and the center tap is electrically connected to the primary coil, and comprises a power line, a capacitor cell and a ground wire, the power line being electrically connected to one end of the capacitor cell, and the ground wire being electrically connected to the other end of the capacitor cell. The center-tapped on-chip transformer having low alternating-current impedance provided in the present invention reduces impedance at a center tap, and reduces parasitic inductance generated by a power line, thereby improving the performance of the transformer.
Need to check novelty before this filing date? Find Prior Art

Citation Information

Patent Citations

  • Marchand balun provided with center tap and used for providing direct-current bias

    CN103078161A

  • Integrated transformer balun with enhanced common-mode rejection for radio frequency, microwave, and millimeter-wave integrated circuits

    CN103985503A

  • Harmonic control CMOS frequency mixer based on transformer structure

    CN107231129A

  • On-chip transformer Balun

    CN107293393A

  • On-chip transformer

    CN108269677A