Transmitters and receivers in SiGe BiCMOS technology for sensitive gas spectroscopy at 222 - 270 GHz

This paper presents transmitterand receiver components for a gas spectroscopy system. The components are fabricated in IHP’s 0.13 μm SiGe BiCMOStechnology. Two fractional-N phase-locked loops are used to generate dedicated frequency ramps for the transmitterand receiver and frequency shift keyingfor the transmitter. The signal-to-noise ratio (SNR) for the absorption line of gaseous methanol (CH3OH) at 247.6 GHz is used as measure for the performance of the system. The implemented mixer-first receiver allows a high performance of the system due to its linearity up to an input powerof - 10dBm. Using a transmitter-array with an output power of 7 dBm an SNR of 4660 (integration time of 2 ms for each data point) was obtained for the 247.6 GHz absorption line of CH3OH at 5 Pa. We have extended our single frequency-band system for 228 – 252 GHz to a 2-band system to cover the range 222 – 270 GHz by combining corresponding two transmittersand receivers with the frequency bands 222 – 256 GHz and 250 – 270 GH...