A Compact, Low-Power and Constant Output Power 330 GHz Voltage-Controlled Oscillator in 130-nm SiGe BiCMOS

Nowadays, terahertz and sub-terahertz frequencies are experiencing a significant interest from both academic and industrial world, since they offer a wide and unused spectrum available for different applications, as high-throughput communications, efficient imaging systems and medical uses. In this work an innovative sub-THz voltage-controlled oscillator (VCO) realized with a 130-nm SiGe process is proposed and described in detail. The technology is the SG13G2 bipolar-complementary-metal-oxide-semiconductor (BiCMOS) provided by IHP foundry. The signal source is conceived for high-resolution THz imaging camera; at design level it has been defined with a push-push architecture and adopts an oscillator core based on a Colpitts topology. State-of-the-art performance has been obtained thanks to the proposed design choices that are uncommon at these frequencies, as for instance, the VCO output taken from the common base node, the use of varactors in anti-series connection and the possibility to define a double output at different harmonic frequencies. These, as well as other innovative expedients, allow to simplify the integration at system level and to achieve compact sizes, very low power consumption and almost constant output power level over the full tuning bandwidth. A relative tuning range of about 5.5% has been obtained around a central frequency of 330 GHz, while the output power is about − 8 dBm with a maximum variation of 0.4 dB. Also the phase noise of − 110 dBc/Hz at 10 MHz offset is very promising. Measurements over different chip samples demonstrate the robustness of the proposed solution and the reliability of the design.