Single chip dynamic nuclear polarization microsystem

The integration on a single chip of the sensitivity-relevant electronics of nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectrometers is a promising approach to improve the limit of detection, especially for samples in the nanoliter and subnanoliter range. Here we demonstrate the co-integration on a single silicon chip of the front-end electronics of an NMR and an ESR detector. The excitation/detection planar spiral microcoils of the NMR and ESR detectors are concentric and interrogate the same sample volume. This combination of sensors allows to perform dynamic nuclear polarization (DNP) experiments using a single-chip integrated microsystem having an area of about 2 mm$^2$. In particular, we report $^1$H DNP-enhanced NMR experiments on liquid samples having a volume of about 1 nL performed at 10.7 GHz(ESR)/16 MHz(NMR). NMR enhancements as large as 50 are achieved on TEMPOL/H$_{2}$O solutions at room temperature. The use of state-of-the-art submicrometer integrated circuit technologies should allow the future extension of the single-chip DNP microsystem approach proposed here up the THz(ESR)/GHz(NMR) region, corresponding the strongest static magnetic fields currently available. Particularly interesting is the possibility to create arrays of such sensors for parallel DNP-enhanced NMR spectroscopy of nanoliter and subnanoliter samples

200 GHz single chip microsystems for dynamic nuclear polarization enhanced NMR spectroscopy

Abstract Dynamic nuclear polarization (DNP) is one of the most powerful and versatile hyperpolarization methods to enhance nuclear magnetic resonance (NMR) signals. A major drawback of DNP is the cost and complexity of the required microwave hardware, especially at high magnetic fields and low temperatures. To overcome this drawback and with the focus on the study of nanoliter and subnanoliter samples, this work demonstrates 200 GHz single chip DNP microsystems where the microwave excitation/detection are performed locally on chip without the need of external microwave generators and transmission lines. The single chip integrated microsystems consist of a single or an array of microwave oscillators operating at about 200 GHz for ESR excitation/detection and an RF receiver operating at about 300 MHz for NMR detection. This work demonstrates the possibility of using the single chip approach for the realization of probes for DNP studies at high frequency, high field, and low temperature

200 GHz single chip dynamic nuclear polarization microsystems

The single chip integration of the sensitivity relevant part of nuclear magnetic resonance (NMR) [1-17], electron spin resonance (ESR) [18-26], and dynamic nuclear polarization (DNP) enhanced NMR detectors [27] is a promising approach to improve the limit of detection, especially for nanoliter and subnanoliter samples. Recently, the single chip integration of a DNP microsystem operating at 11 GHz (ESR)/16 MHz (NMR) has been demonstrated [27]. Here, we report on single chip DNP microsystems operating at 200 GHz (ESR)/300 MHz (NMR). The single chip integrated microsystems consist of a single or an array of microwave oscillators operating at about 200 GHz for ESR excitation/detection and of a radio frequency receiver operating at about 300 MHz with frequency downconversion for NMR detection. The proposed microsystems, integrated into a single chip of about 1 mm^2, eliminate the need of a high power microwave generator (e.g., a gyrotron) and high quality microwave waveguides. The NMR excitation is performed with a non-integrated coil. To exemplify its possible applications, 1H DNP enhanced NMR experiments on solid samples of volumes from 100 pL to 4 nL are performed at temperatures from 15 to 300 K. DNP enhancements as large as 50 are achieved with 2% α,γ-bisdiphenylene-β-phenylallyl in polystyrene (2% BDPA:PS) at 15 K. This work demonstrates the possibility of extending the single chip approach to the realization of probes for DNP studies of nanoliter and subnanoliter samples at high frequency, high field, and low temperature

A Low-Power Microwave HEMT LCLC Oscillator Operating Down to 1.4 K

High-electron-mobility transistors (HEMTs) based on 2-D electron gases (2DEGs) in III-V heterostructures have superior mobility compared with the transistors of silicon-based complementary metal-oxide-semiconductor technologies. The large mobility makes them attractive not only for low-noise and high-power microwave applications but also for low-power applications down to deep cryogenic temperatures. Here, we report on the design and characterization of a low-power HEMT LC Colpitts oscillator operating at 11 GHz whose minimum power consumption is 90 μW at 300 K and 4 μW at 1.4 K. The fully integrated oscillator is based on a single HEMT transistor having a gate length of 70 nm and realized using a 2DEG in In 0.7 Ga 0.3 As. The power consumption of the realized oscillator is the lowest reported in the literature so far for an LC oscillator operating in the same frequency range. In order to investigate the behavior of the oscillator, we also performed a detailed characterization of a stand-alone HEMT transistor from 1.4 to 300 K with a static magnetic field from 0 to 8 T. From the extracted values of the transistor parameters, we estimate and compare the minimum power necessary to start-up oscillations for two different Colpitts topologies

Microwave inductive proximity sensors with sub-pm/Hz1/2 resolution

Inductive proximity sensors are low-cost and versatile detectors achieving resolutions in the nm and sub-nm range. Their typical working frequency ranges from tens of kHz to a few MHz. Operation at higher frequencies is considered as a possible route for the improvement of the performance. Here we report on the design of two microwave inductive proximity sensors based on LC-oscillators operating at 500 MHz and 10 GHz, respectively. Both detectors are based on a frequency-encoded architecture, leading to an intrinsic robustness against interference and signal attenuation. The 500 MHz oscillator is composed of an off-chip resonator with a planar coil having a diameter of 6.4 mm and a CMOS integrated cross-coupled transistor pair. It achieves a frequency noise floor of 0.15 Hz/Hz1/2 (above the 1/f corner frequency of 6 kHz), which leads to a distance resolution of 0.1 pm/Hz1/2 at 110 μm from the coil. The integrated noise in the 1 mHz to 1 kHz bandwidth corresponds to a distance resolution of 45 pmrms. The 10 GHz oscillator is a fully integrated CMOS differential Colpitts with a planar coil having a diameter of 270 μm. It achieves a frequency noise floor of 2 Hz/Hz1/2 (above the 1/f corner frequency of 10 kHz) which leads to a distance resolution of 0.3 pm/Hz1/2 at 70 μm from the coil. The integrated noise in the 1 mHz to 1 kHz bandwidth corresponds to a distance resolution of 100 pmrms

Modeling of Total Ionizing Dose Degradation on 180-nm n-MOSFETs Using BSIM3

This paper presents a modeling approach to simulate the impact of total ionizing dose (TID) degradation on low-power analog and mixed-signal circuits. The modeling approach has been performed on 180-nm n-type metal-oxide-semiconductor field-effect transistors (n-MOSFETs). The effects of the finger number, channel geometry, and biasing voltages have been tested during irradiation experiments. All Berkeley short-channel insulated gate field-effect transistor model (BSIM) parameters relevant to the transistor properties affected by TID have been modified in an algorithmic flow to correctly estimate the sub-threshold leakage current for a given dose level. The maximum error of the model developed is below 8 %. A case study considering a five-stage ring oscillator is simulated with the generated model to show that the power consumption of the circuit increases and the oscillation frequency decreases around by 14 %