Stabilizing a SiGe BiCMOS Transmitter on a Molecular Absorption Line

In many applications, highly stable frequency references are desired which at the same time take up little volume and consume little power. Transmitters and receivers in SiGe BiCMOS technology can be realized on chip-scale, working at in the THz/Millimeter-wave range where many molecules have strong rotational transitions. We stabilized a SiGe BiCMOS transmitter on a rotational transition of carbon monoxide, reaching stabilities of $\lt 10^{-10}$ at 100 s integration.