Design of a 4.2-5.4 GHz differential LC VCO using 0.35 mu m SiGeBiCMOS technology for IEEE 802.11a applications

In this paper, a 4.2-5.4 GHz, -Gm LC voltage controlled oscillator (VCO) for IEEE 802.11a standard is presented. The circuit is designed with AMS 0.35 mu m SiGe BiCMOS process that includes high-speed SiGe Heterojunction Bipolar Transistors (HBTs). According to post-layout simulation results, phase noise is -110.7 dBc/Hz at 1 MHz offset from 5.4 GHz carrier frequency and -113.4 dBc/Hz from 4.2 GHz carrier frequency. A linear, 1200 MHz tuning range is obtained from the simulations, utilizing accumulation-mode varactors. Phase noise was also found to be relatively low because of taking advantage of differential tuning concept. Output power of the fundamental frequency changes between 4.8 dBm and 5.5 dBm depending on the tuning voltage. Based on the simulation results, the circuit draws 2 mA without buffers and 14.5 mA from 2.5 V supply including buffer circuits leading to a total power dissipation of 36.25 mW. The circuit layout occupies an area of 0.6 mm(2) on Si substrate, including DC and RF pads

Realization of a single-chip, SiGe:C-based power amplifier for multi-band WiMAX applications

A fully-integrated Multi-Band PA using 0.25 μm SiGe:C process with an output power of above 25 dBm is presented. The behaviour of the amplifier has been optimized for multi-band operation covering, 2.4 GHz, 3.6 GHz and 5.4 GHz (UWB-WiMAX) frequency bands for higher 1-dB compression point and efficiency. Multi-band operation is achieved using multi-stage topology. Parasitic components of active devices are also used as matching components, in turn decreasing the number of matching component. Measurement results of the PA provided the following performance parameters: 1-dB compression point of 20.5 dBm, gain value of 23 dB and efficiency value of %7 operation for the 2.4 GHz band; 1-dB compression point of 25.5 dBm, gain value of 31.5 dB and efficiency value of %17.5 for the 3.6 GHz band; 1-dB compression point of 22.4 dBm, gain value of 24.4 dB and efficiency value of %9.5 for the 5.4 GHz band. Measurement results show that using multi-stage topologies and implementing each parasitic as part of the matching network component has provided a wider-band operation with higher output power levels, above 25 dBm, with SiGe:C process

A novel interdigitated capacitor based biosensor for detection of cardiovascular risk marker

C-reactive protein (CRP) is a potential biomarker whose elevated levels in humans determine cardiovascular disease risk and inflammation. In this study, we have developed a novel capacitive biosensor for detection of CRP-antigen using capacitor with interdigitated gold (GID) electrodes on nanocrystalline diamond (NCD) surface. The NCD surface served as a dielectric layer between the gold electrodes. GID-surface was functionalized by antibodies and the immobilization was confirmed by Fourier transform spectroscopy (FT-IR) and contact angle measurements. The CRP-antigen detection was performed by capacitive/dielectric-constant measurements. The relaxation time and polarizability constants were estimated using Cole-Cole model. Our results showed that the relaxation time constant (tau) of only CRP-antibody was within 10(-16)-10(-13) s, which was increased to 10(-11) s after the incubation with CRP-antigen, suggesting that the CRP-antigen was captured by the antibodies on GID-surface. In addition, polarizability constant(m) of CRP was also increased upon incubation with increasing concentration of CRP-antigen. Our results showed that the response of GID-NCD-based capacitive biosensor for CRP-antigen was dependent on both concentration (25-800 ng/ml) as well as frequency (50-350 MHz). Furthermore, using optimized conditions, the GID-NCD based capacitive biosensor developed in this study can potentially be used for detection of elevated levels of protein risk markers in suspected subjects for early diagnosis of disease

A novel single-chip RF-voltage-controlled oscillator for bio-sensing applications

A novel interdigiated capacitance (IDC) based affinity biosensor system is presented that detects C-Reactive Protein (CRP), a risk marker for cardiovascular diseases, and transmit the information to a distance location wirelessly. The biosensor system consist of a voltage controlled oscillator (VCO) and an IDC. In the presence of CRP the capacitance of the IDC changes and this directly reflects to the oscillation frequency of the VCO. In the presence of 800 ng/ml antigen the frequency of the system shifts from 1.9438 GHz to 1.94175 GHz and with 64 ug/ml frequency shifts from 1.95975 GHz to 1.94875 GHz with -120 dBc/Hz phase noise

Label-free biosensors for the detection and quantification of cardiovascular risk markers

This paper presents a biosensor implementation for the detection of protein molecules using specific antibodies. Affinity sensors allow the detection and quantification of target molecules in complex mixtures by affinity-based interactions. Immobilized antibody molecules are the probes that bind to specific protein molecules (targets) in biological fluids. In this study, inter-digitated electrodes in the form of capacitance on glass slide were designed, fabricated and used to measure the changes in the dielectric properties of the inter-digitated capacitances. Our results in this study present that with a careful design of micro-interdigitated capacitors, a wider dynamic range and higher sensitivity can be achieved for the detection and quantification of C-Reeactive Protein

Biosensors for cardiac biomarkers detection: a review

The cardiovascular disease (CVD) is considered as a major threat to global health. Therefore, there is a growing demand for a range of portable, rapid and low cost biosensing devices for the detection of CVD. Biosensors can play an important role in the early diagnosis of CVD without having to rely on hospital visits where expensive and time-consuming laboratory tests are recommended. Over the last decade, many biosensors have been developed to detect a wide range of cardiac marker to reduce the costs for healthcare. One of the major challenges is to find a way of predicting the risk that an individual can suffer from CVD. There has been considerable interest in finding diagnostic and prognostic biomarkers that can be detected in blood and predict CVD risk. Of these, C-reactive protein (CRP) is the best known biomarker followed by cardiac troponin I or T (cTnI/T), myoglobin, lipoprotein-associated phospholipase A(2), interlukin-6 (IL-6), interlukin-1 (IL-1), low-density lipoprotein (LDL), myeloperoxidase (MPO) and tumor necrosis factor alpha (TNF-α) has been used to predict cardiovascular events. This review provides an overview of the available biosensor platforms for the detection of various CVD markers and considerations of future prospects for the technology are addressed

A 7-bit reverse-saturated SiGe HBT discrete gain step attenuator

In this study, the analysis, design and measured results of a fully integrated 7-Bit step attenuator implemented in a 0.25-μm Silicon-Germanium (SiGe) BiCMOS process technology, are described. The attenuator is designed based on delicately ordered and cascaded Π/T type attenuation blocks, which are comprised of series/shunt switches employing SiGe hetero-junction bipolar transistors (HBTs) with peak fT/fmax of 110/180 GHz. HBTs are employed as a series switch to decrease the insertion-loss of the attenuator. Moreover, to authors’ best knowledge, this is the first study presenting the effect of employing reverse-saturated HBTs as a shunt switch for each attenuation blocks. Thanks to this advancement, the highest input-referred 1-dB compression point (IP1dB) is reported for Si-based similar studies. This method also decreases the insertion-loss of the proposed attenuator. The measurements result in the state-of-the-art performance with 28.575 dB attenuation range by 0.225 dB gain steps while maintaining 7-bit amplitude resolution across 6.6 GHz to 12.8 GHz frequency band, where RMS phase error remains below 3.3∘ and insertion loss (IL) is less than 12.4 dB. The measured IP1dB of the attenuator is 13.5 dBm while drawing 8 mA from 3.3 V supply. The die occupies an area of 1.37 mm x 0.56 mm excluding pads

Review on carbon-derived, solid-state, micro and nano sensors for electrochemical sensing applications

The aim of this review is to summarize the most relevant contributions in the development of electrochemical sensors based on carbon materials in the recent years. There have been increasing numbers of reports on the first application of carbon derived materials for the preparation of an electrochemical sensor. These include carbon nanotubes, diamond like carbon films and diamond film-based sensors demonstrating that the particular structure of these carbon material and their unique properties make them a very attractive material for the design of electrochemical biosensors and gas sensors. Carbon nanotubes (CNT) have become one of the most extensively studied nanostructures because of their unique properties. CNT can enhance the electrochemical reactivity of important biomolecules and can promote the electron-transfer reactions of proteins (including those where the redox center is embedded deep within the glycoprotein shell). In addition to enhanced electrochemical reactivity, CNT-modified electrodes have been shown useful to be coated with biomolecules (e.g., nucleic acids) and to alleviate surface fouling effects (such as those involved in the NADH oxidation process). The remarkable sensitivity of CNT conductivity with the surface adsorbates permits the use of CNT as highly sensitive nanoscale sensors. These properties make CNT extremely attractive for a wide range of electrochemical sensors ranging from amperometric enzyme electrodes to DNA hybridization biosensors. Recently, a CNT sensor based fast diagnosis method using non-treated blood assay has been developed for specific detection of hepatitis B virus (HBV) (human liver diseases, such as chronic hepatitis, cirrhosis, and hepatocellular carcinoma caused by hepatitis B virus). The linear detection limits for HBV plasma is in the range 0.5–3.0 μL−1 and for anti- HBVs 0.035–0.242 mg/mL in a 0.1 M NH4H2PO4 electrolyte solution. These detection limits enables early detection of HBV infection in suspected serum samples. Therefore, non-treated blood serum can be directly applied for real-time sensitive detection in medical diagnosis as well as in direct in vivo monitoring. Synthetic diamond has been recognized as an extremely attractive material for both (bio-) chemical sensing and as an interface to biological systems. Synthetic diamond have outstanding electrochemical properties, superior chemical inertness and biocompatibility. Recent advances in the synthesis of highly conducting nanocrystalline-diamond thin films and nano wires have lead to an entirely new class of electrochemical biosensors and bio-inorganic interfaces. In addition, it also combines with development of new chemical approaches to covalently attach biomolecules on the diamond surface also contributed to the advancement of diamond-based biosensors. The feasibility of a capacitive field-effect EDIS (electrolyte-diamond-insulatorsemiconductor) platform for multi-parameter sensing is demonstrated with an O-terminated nanocrystalline-diamond (NCD) film as transducer material for the detection of pH and penicillin concentration. This has also been extended for the label-free electrical monitoring of adsorption and binding of charged macromolecules. One more recent study demonstrated a novel bio-sensing platform, which is introduced by combination of a) geometrically controlled DNA bonding using vertically aligned diamond nano-wires and b) the superior electrochemical sensing properties of diamond as transducer material. Diamond nanowires can be a new approach towards next generation electrochemical gene sensor platforms. This review highlights the advantages of these carbon materials to promote different electron transfer reactions specially those related to biomolecules. Different strategies have been applied for constructing carbon material-based electrochemical sensors, their analytical performance and future prospects are discussed