Tunable 500 GHz transmitter array in SiGe technology for gas spectroscopy

A 500 GHz system for gas spectroscopy is presented, which includes an integrated SiGe 4 × 1 transmitter (TX) array, a Golay cell as a detector and a 1.9 m-long gas absorption cell. The local oscillator (LO) of the TX array is controlled by an external phase-locked loop, whose reference frequency is swept. The four TX branches involve frequency quadruplers (x4). The TX branches are fed by a 120 GHz power division network, which is connected to the LO. The estimated radiated output power of the TX array is -7 dBm at 500 GHz. The absorption spectrum of gaseous methanol is shown for 494-500 GHz.