A Wideband True Time Delay Circuit Using 0.25 µm GaN HEMT Technology

Area of Science:

• Electrical Engineering
• Materials Science
• Antenna Technology

Background:

• Phased array antennas require precise signal timing for beam steering.
• Beam squint, a frequency-dependent beam deviation, degrades antenna performance.
• Gallium Nitride (GaN) High-Electron-Mobility Transistor (HEMT) technology offers high-frequency and high-power advantages.

Purpose of the Study:

• To present a wideband 4-bit true time delay integrated circuit (IC) for beam-squint-free phased array antennas.
• To demonstrate the feasibility of using GaN HEMT technology for true time delay applications.
• To achieve compact chip size and high performance.

Main Methods:

• Implementation of a switched path circuit topology using Double Pole Double Throw (DPDT) and Single Pole Single Throw (SPDT) switches.
• Utilization of Compact LC (CLC) π-networks with lumped elements for delay lines.
• Integration of a negative voltage generator and SPI controller on a Printed Circuit Board (PCB) due to GaN technology limitations.

Main Results:

• Achieved a maximum time delay of ~182 ps with a resolution of 10.5 ps over a DC-6 GHz bandwidth.
• Demonstrated Root Mean Square (RMS) time delay and amplitude errors below 5 ps and 0.6 dB, respectively.
• Measured insertion loss <6.8 dB, return losses >10 dB, and near-zero current consumption.

Conclusions:

• This work represents the first demonstration of a true time delay IC utilizing GaN HEMT technology.
• The developed IC effectively mitigates beam squint in phased array antennas.
• The GaN HEMT-based true time delay IC offers a promising solution for advanced antenna systems.