Wideband SiGe-HBT Low-Noise Amplifier with Resistive Feedback and Shunt Peaking.

In this work, the design of a wideband low-noise amplifier (LNA) using a resistive feedback network is proposed for potential multi-band sensing, communication, and radar applications. For achieving wide operational bandwidth and flat in-band characteristics simultaneously, the proposed LNA employs a variety of circuit design techniques, including a voltage-current (shunt-shunt) negative feedback configuration, inductive emitter degeneration, a main branch with an added cascode stage, and the shunt-peaking technique. The use of a feedback network and emitter degeneration provides broadened transfer characteristics for multi-octave coverage and a real impedance for input matching, respectively. In addition, the cascode stage pushes the band-limiting low-frequency pole, due to the Miller capacitance, to a higher frequency. Lastly, the shunt-peaking approach is optimized for the compensation of a gain reduction at higher frequency bands. The wideband LNA proposed in this study is fabricated using a commercial 0.13 µm silicon-germanium (SiGe) BiCMOS process, employing SiGe heterojunction bipolar transistors (HBTs) as the circuit's core active elements in the main branch. The measurement results show an operational bandwidth of 2.0-29.2 GHz, a noise figure of 4.16 dB (below 26.5 GHz, which was the measurement limit), and a total power consumption of 23.1 mW under a supply voltage of 3.3 V. Regarding the nonlinearity associated with large-signal behavior, the proposed LNA exhibits an input 1-dB compression (IP1dB) point of -5.42 dBm at 12 GHz. These performance numbers confirm the strong viability of the proposed approach in comparison with other state-of-the-art designs.

A highly sensitive and selective diagnostic assay based on virus nanoparticles.

Early detection of the protein marker troponin I in patients with a higher risk of acute myocardial infarction can reduce the risk of death from heart attacks. Most troponin assays are currently based on the conventional enzyme linked immunosorbent assay and have detection limits in the nano- and picomolar range. Here, we show that by combining viral nanoparticles, which are engineered to have dual affinity for troponin antibodies and nickel, with three-dimensional nanostructures including nickel nanohairs, we can detect troponin levels in human serum samples that are six to seven orders of magnitude lower than those detectable using conventional enzyme linked immunosorbent assays. The viral nanoparticle helps to orient the antibodies for maximum capture of the troponin markers. High densities of antibodies on the surfaces of the nanoparticles and nanohairs lead to greater binding of the troponin markers, which significantly enhances detection sensitivities. The nickel nanohairs are re-useable and can reproducibly differentiate healthy serum from unhealthy ones. We expect other viral nanoparticles to form similar highly sensitive diagnostic assays for a variety of other protein markers.