A Compact 3-30-GHz 68.5-ps CMOS True-Time Delay for Wideband Phased Array Systems

Minjae Jung, Byung Wook Min

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


This article presents a compact 4-bit switched-line true-time delay (TTD) circuit over a wide frequency range extending from 3 to 30 GHz using novel delay elements. The delay elements, namely, the cascading coupled all-pass network (CAPN) and noncoupled all-pass network (NCAPN), were employed in the proposed TTD circuit to improve the delay-bandwidth product (DBW) while maintaining its compact size and low delay variation (DV). For comparison, a theoretical analysis for understanding the group delay feature of the APN with various coupling coefficients is presented along with low-pass network (LPN). To verify the proposed structure, the proposed delays are applied to construct the 4-bit switched-line TTD by utilizing two single-pole double-through (SPDT) and three double-pole double-through (DPDT) switches in a 28-nm CMOS process. The circuit has a compact size of 1.7 mm $\times0.2$ mm, with a maximum delay of 68.5 ps and a minimum delay of 4.6 ps. The measured average insertion loss is 13.5 dB, and the in/out return loss is better than 10 dB across 3-30 GHz. The measured rms delay and gain errors are less than 2 ps and 3.2 dB, respectively, over the operating frequency range. To the best of our knowledge, the proposed TTD achieves the largest figure of merit (FoM) among the integrated TTD circuits.

Original languageEnglish
Article number9204450
Pages (from-to)5371-5380
Number of pages10
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number12
Publication statusPublished - 2020 Dec

Bibliographical note

Publisher Copyright:
© 1963-2012 IEEE.

All Science Journal Classification (ASJC) codes

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


Dive into the research topics of 'A Compact 3-30-GHz 68.5-ps CMOS True-Time Delay for Wideband Phased Array Systems'. Together they form a unique fingerprint.

Cite this