300-GHz Integrated Heterodyne Receiver Chain for Phased-Array with Wide IF Bandwidth
This paper presents a fully integrated terahertz phased-array receiver with a wide IF bandwidth designed using a 250-nm InP DHBT technology. The phased-array receiver consists of a variable-gain low-noise amplifier (VG-LNA), phase shifter, down-conversion mixer, and injection locking local oscillator (ILO). Each circuit block is designed to be broadband to achieve a wide receiver bandwidth.
The VG-LNA adopts a cascade topology with a current steering technique to control the gain. While the control voltage (Vcon) varies from 2 to 3.6 V, the gain varies from 15.6 to 0 dB at 300 GHz. The noise figure is no higher than 15 dB at all Vcon conditions. The phase shifter uses a current combining structure based on Gilbert cells. The peak conversion gain is -10 dB at 303 GHz and the 3 dB bandwidth is 52 GHz extending from 270 to 322 GHz. The LO employs an injection locking technique. The locking range is from 260 to 328 GHz (22.7%) when a 10-dBm signal is injected. The maximum output power is 0.5 dBm at 300 GHz. The Gilbert-cell-based down-conversion mixer shows 72 GHz gain-bandwidth extending from 252 GHz to 324 GHz.
The proposed fully integrated phased-array receiver shows a wide bandwidth characteristic. When the control voltage is set to 2.0 V, the peak conversion gain is 12.3 dB and the 3-dB bandwidth reaches 45 GHz from 270 GHz to 315 GHz.