A fully integrated low-power K-band chem-bio-sensor with on-chip DC read-out in SiGe BiCMOS technology

This paper presents the design of an integrated low-power K-band chem-bio-sensor in standard 0.13 μm SiGe BiCMOS technology incorporated with sensing and on-chip read-out circuitry together. The material under test (MUT) is exposed on an open-stub inside a Colpitts oscillator; the open-stub works as a capacitive sensor and the oscillator results in a permittivity dependent output frequency. The frequency information is translated into DC voltage using a frequency discriminator comprised of a delay line, a single transistor mixer and a low-pass filter. The sensor has been calibrated using iso-propanol and ethanol, the sensitivity is demonstrated using solutions of methanol-ethanol mixtures with concentration differences of 5 % around a mixture ratio of 50:50. It is 2.1 in mm² in size and it consumes 127 mW power. Along with low power consumption, this makes it a compact solution capable of performing minimal invasive investigations of chemicals and bio-materials.