The Stimulatory Gαs Protein Is Involved in Olfactory Signal Transduction in Drosophila

Seven-transmembrane receptors typically mediate olfactory signal transduction by coupling to G-proteins. Although insect odorant receptors have seven transmembrane domains like G-protein coupled receptors, they have an inverted membrane topology, constituting a key difference between the olfactory systems of insects and other animals. While heteromeric insect ORs form ligand-activated non-selective cation channels in recombinant expression systems, the evidence for an involvement of cyclic nucleotides and G-proteins in odor reception is inconsistent. We addressed this question in vivo by analyzing the role of G-proteins in olfactory signaling using electrophysiological recordings. We found that Gαs plays a crucial role for odorant induced signal transduction in OR83b expressing olfactory sensory neurons, but not in neurons expressing CO2 responsive proteins GR21a/GR63a. Moreover, signaling of Drosophila ORs involved Gαs also in a heterologous expression system. In agreement with these observations was the finding that elevated levels of cAMP result in increased firing rates, demonstrating the existence of a cAMP dependent excitatory signaling pathway in the sensory neurons. Together, we provide evidence that Gαs plays a role in the OR mediated signaling cascade in Drosophila

Topological and Functional Characterization of an Insect Gustatory Receptor

Insect gustatory receptors are predicted to have a seven-transmembrane structure and are distantly related to insect olfactory receptors, which have an inverted topology compared with G-protein coupled receptors, including mammalian olfactory receptors. In contrast, the topology of insect gustatory receptors remains unknown. Except for a few examples from Drosophila, the specificity of individual insect gustatory receptors is also unknown. In this study, the total number of identified gustatory receptors in Bombyx mori was expanded from 65 to 69. BmGr8, a silkmoth gustatory receptor from the sugar receptor subfamily, was expressed in insect cells. Membrane topology studies on BmGr8 indicate that, like insect olfactory receptors, it has an inverted topology relative to G protein-coupled receptors. An orphan GR from the bitter receptor family, BmGr53, yielded similar results. We infer, from the finding that two distantly related BmGrs have an intracellular N-terminus and an odd number of transmembrane spans, that this is likely to be a general topology for all insect gustatory receptors. We also show that BmGr8 functions independently in Sf9 cells and responds in a concentration-dependent manner to the polyalcohols myo-inositol and epi-inositol but not to a range of mono- and di-saccharides. BmGr8 is the first chemoreceptor shown to respond specifically to inositol, an important or essential nutrient for some Lepidoptera. The selectivity of BmGr8 responses is consistent with the known responses of one of the gustatory receptor neurons in the lateral styloconic sensilla of B. mori, which responds to myo-inositol and epi-inositol but not to allo-inositol

Comparison of inductor types for phase noise optimized oscillators in SiGe at 34 GHz

In this paper two integrated auxiliary VCOs working at a center frequency of 34 GHz for use in a 240 GHz transceiver chip in SiGe technology for ultra-wideband radar applications are presented. The oscillators are using different realizations of the resonator inductance which are compared in terms of quality factor and their influence on the phase noise of the resulting oscillator output signal. The improvement in quality factor at a frequency of 34 GHz between the oscillator using microstrip transmission lines and the oscillator using spiral inductors is simulated to be around 76 % which causes a simulated absolute improvement in output signal phase noise of around 4.5 dB. Both oscillators are realized as test circuits with which the difference can be measured to be around 5 dB proving the advantage of spiral inductors in terms of quality factor for frequencies around 34 GHz resulting in an integrated VCO design providing a low phase noise of -107 dBc/Hz @ 1 MHz offset and a wide tuning range of 6.78 GHz

High precision D-band FM - CW-radar sensor based on a wideband SiGe-transceiver MMIC

In this paper, a miniaturized D-band frequency-modulated continuous-wave (FMCW) radar sensor with 48-GHz bandwidth (32.8%, 122-170 GHz) and a high measurement rate of > 1 kHz for multi-target vibration measurements is presented. The sensor is based on a SiGe transceiver monolithic microwave integrated circuit manufactured via Infineon's B7HF200 bipolar production technology with an fT of 170 GHz and fmax of 250 GHz. Gilbert cell, push-pull, and varactor-based doubler concepts on manufactured chips are compared, and the most promising signal source is embedded into a transceiver chip, which forms the main component of the presented radar sensor. The maximum output power of the system is ≈ -10 dBm and a phase noise of ≈ -80 dBc/Hz is achieved. Measurements are provided to demonstrate the sensor characteristics and show the promising results of FMCW radar in highest precision distance and multi-target vibration measurement applications. Due to the covered wide bandwidth, a range resolution of 5.88 mm is achieved ( -6-dB width, Tukey window). The sensor's distance measurement repeatability is 290 nm (65 nm with 10 × averaging and 0.5-m target distance), and the distance measurement accuracy is m for a target in 65-cm distance moving 1 cm. Additionally, vibration measurement results and range-Doppler plots for advanced multi-target applications are presented

A 61 GHz SiGe transmitter chip for energy and data transmission of passive RFID single chip tags with integrated antennas

This paper presents a SiGe transmitter chip for short-range devices in the 61 GHz ISM frequency band. The presented transmitter consists of a fundamental VCO, a PA, lumped element Wilkinson-Dividers and a static divide-by-16 chain for stabilization in a PLL. Two variants of the transmitter are fabricated with supply voltages of 3.3 V and 5 V in a modern 130nm SiGe BiCMOS technology with HBTs offering an ft of 250 GHz and fmax of 370 GHz. The main goal of this work is to achieve an efficient signal source to supply a passive RFID tag with the maximum allowed 20 dBm EIRP for short range devices. The transmitter chips achieve a peak output power of 17 dBm, PAEpa of 18.8% and DC-to-RF efficiency of 12.9% (excluding the divider). At 61 GHz a phase noise of -102 dBc/Hz is achieved. The power consumption for the chips are 710 mW and 482 mW for the 5 V and 3.3 V variant, respectively

Next generation integrated SiGe mm-wave circuits for automotive radar sensors

In this paper, radar transmitter circuits for next generation automotive radar sensors are presented. A 79 GHz radar transmitter with an output power of 14.5 dBm consuming only 165 mA (including frequency dividers) from a 3.3 V supply voltage clearly shows the advantage of using an improved SiGe technology with an fmax of 380 GHz. In addition, two radar transmitters for higher frequencies (around 150 GHz) based on frequency doubler circuits are showing the potential of SiGe technologies. The first transmitter achieves an output power of 3 dBm (single ended) at 144 GHz, whereas the second transmitters delivers a differential output power of 0 dBm at 150 GHz. Both transmitters achieve an ultra-wide tuning range of about 45 GHz

A compact ultra-wideband mmWave radar sensor at 80 GHz based on a SiGe transceiver chip (Focused session on highly-integrated millimeter-wave radar sensors in SiGe BiCMOS technologies)

This papers describes the capabilities of modern SiGe semiconductor technologies for the highly-integrated realization of Frequency-Modulated Continuous Wave (FMCW) Radar sensors. Based on an ultra-wideband oscillator, synthesizer and receiver, an ultra-wide bandwidth of 25 GHz around a center frequency of 80 GHz is demonstrated. This enables high-resolution radar measurements with a multi-target resolution of 7.1 mm and an absolute distance accuracy better than 1 μm, which enables new potentials for contact-free distance measurements even in harsh environments

A 61-GHz SiGe Transceiver Frontend for Energy and Data Transmission of Passive RFID Single-Chip Tags With Integrated Antennas

This paper presents SiGe-based transmitter and receiver chips for a radio frequency identification (RFID) frontend in the 61-GHz industrial, scientific, and medical (ISM) frequency band. The chips are fabricated in a modern 130-nm SiGe BiCMOS technology with HBTs offering an fT of 250 GHz and fmax of 370 GHz. The presented transmitter consists of a fundamental voltage-controlled oscillator (VCO), a power amplifier (PA), lumped element Wilkinson power dividers, and a static divide-by-16 chain for stabilization within a phase-locked loop (PLL). Two variants of the transmitter are fabricated with supply voltages of 3.3 and 5 V, respectively. The transmitters are designed to provide an efficient signal source to supply a passive RFID tag with the maximum allowed 20-dBm effective isotropic radiated power (EIRP) for short-range devices. The 3.3-V transmitter chip achieves a peak output power of 17 dBm, PAEPA of 18.6% and dc-to-RF efficiency of 12.9% (excluding the divider). A t 61 GHz, a phase noise of -102 dBc/Hz at 1 MHz offset is achieved. The power consumption for the 5- and 3.3-V transmitter chips is 710 and 482 mW, respectively. The receiver chip is implemented as two Gilbert cell mixers in-phase quadrature configuration to compensate for destructive interference that may be caused by varying distance between reader and tag

Characteristics of Picoliter Droplet Dried Residues as Standards for Direct Analysis Techniques

The characteristics of dried residues of picodroplets of single-, two-, and three-element aqueous solutions, which qualify these as reference materials in the direct analysis of single particles, single cells, and other microscopic objects using, e.g., laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOF-MS) and micro-X-ray fluorescence (MXRF), were evaluated. Different single-, two-, and three-element solutions (0.01-1 g/L) were prepared in picoliter volume (around 130 pL) with a thermal inkjet printing technique. An achievable dosing precision of 4-15% was calculated by total reflection X-ray fluorescence (TXRF) determination of the transferred elemental mass of an array of 100 droplets. The size of the dried residues was determined by optical microscopy to be 5-20 microm in diameter depending on the concentration and the surface material. The elemental distribution of the dried residues was determined with synchrotron micro-X-ray fluorescence (SR-MXRF) analyses. The MXRF results show high uniformity for element deposition of every single droplet with an RSTD of 4-6% depending on the concentration of spotted solution. The shape and height profile of dried residues from picoliter droplets were studied using atomic force microscopy (AFM). It was found that these dry to give symmetrical spherical segments with maximum heights of 1.7 microm. The potential of this technique for direct LA-ICP-TOF-MS analysis is shown