4,828 research outputs found
Advances in Development of Quartz Crystal Oscillators at Liquid Helium Temperatures
This work presents some recent results in the field of liquid helium {bulk
acoustic wave} oscillators. The discussion covers the whole development
procedure starting from component selection and characterization and concluding
with actual phase noise measurements. The associated problems and limitations
are discussed. The unique features of obtained phase noise power spectral
densities are explained with a proposed extension of the Leeson effect.Comment: Cryogenics, 201
Thermal Kinetic Inductance Detectors for Millimeter-Wave Astrophysics
Thermal Kinetic Inductance Detectors (TKIDs) combine the excellent noise performance of traditional bolometers with a radio frequency (RF) multiplexing architecture that enables the large detector counts needed for the next generation of millimeter-wave instruments. Here we present dark prototype TKID pixels that demonstrate a noise equivalent power NEP = 2Ă10â»Âčâ·âW/Hz with a 1/f knee at 0.1 Hz, suitable for background-limited noise performance at 150 GHz from a ground-based site. We discuss the optimizations in the device design and fabrication techniques to realize optimal electrical performance and high quality factors at a bath temperature of 250 mK
Giant capacitance of a plane capacitor with a two-dimensional electron gas in a magnetic field
If a clean two-dimensional electron gas (2DEG) with small concentration
comprises one (or both) electrodes of a plane capacitor, the resulting
capacitance can be larger than the "geometric capacitance" determined
by the physical separation between electrodes. A recent paper [1] argued
that when the effective Bohr radius of the 2DEG satisfies , one
can achieve at low concentration . Here we show that even
for devices with , including graphene, for which is effectively
infinite, one also arrives at at low electron concentration if there
is a strong perpendicular magnetic field.Comment: 6 pages, 5 figures; updated discussion about bilayer systems; added
discussion of fractional quantum Hall state
Noise Characterization and Filtering in the MicroBooNE Liquid Argon TPC
The low-noise operation of readout electronics in a liquid argon time
projection chamber (LArTPC) is critical to properly extract the distribution of
ionization charge deposited on the wire planes of the TPC, especially for the
induction planes. This paper describes the characteristics and mitigation of
the observed noise in the MicroBooNE detector. The MicroBooNE's single-phase
LArTPC comprises two induction planes and one collection sense wire plane with
a total of 8256 wires. Current induced on each TPC wire is amplified and shaped
by custom low-power, low-noise ASICs immersed in the liquid argon. The
digitization of the signal waveform occurs outside the cryostat. Using data
from the first year of MicroBooNE operations, several excess noise sources in
the TPC were identified and mitigated. The residual equivalent noise charge
(ENC) after noise filtering varies with wire length and is found to be below
400 electrons for the longest wires (4.7 m). The response is consistent with
the cold electronics design expectations and is found to be stable with time
and uniform over the functioning channels. This noise level is significantly
lower than previous experiments utilizing warm front-end electronics.Comment: 36 pages, 20 figure
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Noise shaping Asynchronous SAR ADC based time to digital converter
Time-to-digital converters (TDCs) are key elements for the digitization of timing information in modern mixed-signal circuits such as digital PLLs, DLLs, ADCs, and on-chip jitter-monitoring circuits. Especially, high-resolution TDCs are increasingly employed in on-chip timing tests, such as jitter and clock skew measurements, as advanced fabrication technologies allow fine on-chip time resolutions. Its main purpose is to quantize the time interval of a pulse signal or the time interval between the rising edges of two clock signals. Similarly to ADCs, the performance of TDCs are also primarily characterized by Resolution, Sampling Rate, FOM, SNDR, Dynamic Range and DNL/INL. This work proposes and demonstrates 2nd order noise shaping Asynchronous SAR ADC based TDC architecture with highest resolution of 0.25 ps among current state of art designs with respect to post-layout simulation results. This circuit is a combination of low power/High Resolution 2nd Order Noise Shaped Asynchronous SAR ADC backend with simple Time to Amplitude converter (TAC) front-end and is implemented in 40nm CMOS technology. Additionally, special emphasis is given on the discussion on various current state of art TDC architectures.Electrical and Computer Engineerin
Inter-Pixel Crosstalk in Teledyne Imaging Sensors (TIS) H4RG-10 Detectors
CMOS-hybrid arrays have recently surfaced as competitive optical detectors
for use in ground- and space-based astronomy. One source of error in these
detectors that does not appear in more traditional CCD arrays is the
inter-pixel capacitance component of crosstalk. In this paper we use a single
pixel reset method to model inter-pixel capacitance (IPC). We combine this IPC
model with a model for charge diffusion to estimate the total crosstalk on H4RG
arrays. Finally, we compare our model results to Fe55 data obtained using an
astrometric camera built to test the H4RG-B0 generation detectors.Comment: Accepted to Applied Optics 03-26-1
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