A comparison is made on high-frequency SiGe imagers to investigate the performance enhancement with circuit-level approaches: employing a front-end low noise amplifier (LNA) and employing heterodyne topology. Two imagers operating near 130 GHz, one with and the other without an LNA, were compared for the responsivity and the noise equivalent power (NEP). Also, two imagers operating near 300 GHz, one in direct and the other in heterodyne topology, were compared for the same parameters. Inserting a front-end LNA has led to changes in the peak responsivity and the minimum NEP with a factor of 63.5 and 0.011, respectively, near 130 GHz. Employing heterodyne topology for the 300 GHz imager resulted in changes with a factor of 52.8 and 0.18 for the same parameters.