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Open Access Publications from the University of California

Scholarly Works (13 results)

  • Article
  • Peer Reviewed
LBL Publications (2019)
Programmable Electronic Termination and Line Driver (PETAL) is a 16-channel ADC driver chip that provides single-ended-to-differential conversion and column biasing for high-speed CMOS image sensors. By increasing the level of integration, the number of driver chips and the associated number of passives and the routing area are reduced, enabling smaller physical cameras. Power dissipation is reduced relative to many commercial approaches by the use of low-voltage CMOS technology and the increased level of integration. The driver chip also supplies programmable bias currents to the sensor, further reducing the number of required components on the camera board. The driver, fabricated in 180-nm CMOS technology, achieves settling to 0.1% in 11 ns with input noise of 89.9- \mu \text{V} rms. The crosstalk between channels is below -56 dB. The power dissipation is 10.5 mW/channel. When applied to the readout of a high-speed X-ray sensor, the prototype reduced board area by 84% (from 100 to 16 mm2) and power dissipation by 25%.
    Cover page: PETAL: A Multichannel Differential ADC Driver for High-Speed CMOS Image Sensors
    • Article
    • Peer Reviewed
    LBL Publications (2021)
    A 24-channel application-specific integrated circuit (ASIC) for the readout of high-speed CMOS active pixel sensors for charged particle detection is presented. The chip comprises 24 preamplifiers, 24 distinct 12-bit, 25 MSPS Pipelined analog-to-digital converters (ADCs) with self-calibration, an internal phase-locked loop (PLL), and a 3 Gbps serial interface that conforms to the JESD204B standard. To simplify interfacing with a variety of sensors, the ASIC also includes an automatic offset calibration loop. The high level of integration of the ASIC reduces overall system cost and area, and exploiting the signal characteristics of the image sensor allows the ADC to be optimized for reduced power dissipation. The use of an integrated serializer and an industry standard protocol simplifies integration of the ASIC into a complete camera system. The ASIC, called the High-Speed Image Preprocessor Targeted for Electron Readout, or HIPSTER, with a die area of 64.26 mm2, is packaged in a 480-ball grid array (BGA) and is fabricated in 180-nm CMOS technology. HIPSTER achieves typical differential nonlinearity (DNL) < 0.55 LSB, input-referred thermal noise of $114.5~\mu \text{V}$ -rms, and a bit error rate (BER) of better than 10-14. The power dissipation is 98 mW/channel.
      Cover page: A 24-Channel Digitizer With a JESD204B-Compliant Serial Interface for High-Speed Detectors
      • Article
      • Peer Reviewed
      LBL Publications (2017)
      We have developed a charge-coupled device (CCD) with 5 μm × 45 μm pixels on high-resistivity silicon. The fully depleted 200 μm-thick silicon detector is back-illuminated through a 10 nm-thick in situ doped polysilicon window and is thus highly efficient for soft through >8 keV hard X-rays. The device described here is a 1.5 megapixel CCD with 2496 × 620 pixels. The pixel and camera geometry was optimized for Resonant Inelastic X-ray Scattering (RIXS) and is particularly advantageous for spectrometers with limited arm lengths. In this article, we describe the device architecture, construction and operation, and its performance during tests at the Advance Light Source (ALS) 8.0.1 RIXS beamline. The improved spectroscopic performance, when compared with a current standard commercial camera, is demonstrated with a ∼280 eV (CK) X-ray beam on a graphite sample. Readout noise is typically 3-6 electrons and the point spread function for soft CK X-rays in the 5 μm direction is 4.0 μm ± 0.2 μm. The measured quantum efficiency of the CCD is greater than 75% in the range from 200 eV to 1 keV.
        Cover page: A 5-μm pitch charge-coupled device optimized for resonant inelastic soft X-ray scattering
        • Article
        • Peer Reviewed
        LBL Publications (2020)
        A 256-channel readout application specific integrated circuit (ASIC) called the very low-noise analog sampling engine (VASE) intended for the readout of column-parallel charge-coupled devices (CP-CCDs), is presented. Each channel uses a charge-sensitive amplifier and a first-order dual-gain sigma-delta analog-to-digital converter (ADC) that act as the front end of an extended counting ADC. The extended counting ADC directly implements correlated multiple-sampling as part of its operation. To reduce the noise due to input capacitance and to ensure a compact camera, the VASE input bonding pads are pitch matched to the CP-CCD to allow chip-to-chip bonding with minimal parasitic capacitance. The chip is designed in a modular way with each 16 input channels sharing a single differential analog output and digital serializer. VASE, with a die area of 38.1 mm2 and fabricated in 180-nm CMOS technology, achieves 22 e- equivalent noise charge (ENC) and a dynamic range of 190 ke- (78.7 dB) at a 4-MHz pixel rate (corresponding to a frame rate of 32 kfps when a 256 × 256 pixel sensor is read out on both sides) while dissipating 10.1 mW per channel. The prototype has been used to successfully image X-ray diffraction at a soft X-ray synchrotron.
          Cover page: A 4-MHz, 256-Channel Readout ASIC for Column-Parallel CCDs With 78.7-dB Dynamic Range
          • Article
          Lawrence Berkeley National Laboratory (2004)

          We report on the development of a new technique for the measurement of the longitudinal beam profile in storage rings. This technique, which has been successfully demonstrated at the Advanced Light Source, mixes the synchrotron radiation with the light from a mode-locked solid state laser oscillator in a non-linear crystal. The up-converted radiation is then detected with a photomultiplier and processed to extract, store, and display the required information. The available choices of laser repetition frequency, pulse width, and phase modulation give a wide range of options for matching the bunch configuration of a particular storage ring. Besides the dynamic measurement of the longitudinal profile of each bunch, the instrument can monitor the evolution of the bunch tails, the presence of untrapped particles and their diffusion into nominally empty RF buckets ("ghost bunches").

            Cover page: Measurement of the beam longitudinal profile in a storage ring by non-linear laser mixing
            • Article
            • Peer Reviewed
            UC San Francisco Previously Published Works (2016)
            © 2016 Rübel, Dougherty, Prabhat, Denes, Conant, Chang and Bouchard.Neuroscience continues to experience a tremendous growth in data; in terms of the volume and variety of data, the velocity at which data is acquired, and in turn the veracity of data. Thes
              • Article
              • Peer Reviewed
              LBL Publications (2017)
              The introduction of direct electron detectors enabled the structural biology revolution of cryogenic electron microscopy. Direct electron detectors are now expected to have a similarly dramatic impact on time-resolved MeV electron microscopy, particularly by enabling both spatial and temporal jitter correction. Here we report on the commissioning of a direct electron detector for time-resolved MeV electron microscopy. The direct electron detector demonstrated MeV single electron sensitivity and is capable of recording megapixel images at 180 Hz. The detector has a 15-bit dynamic range, better than 30-μm spatial resolution and less than 20 analogue-to-digital converter count RMS pixel noise. The unique capabilities of the direct electron detector and the data analysis required to take advantage of these capabilities are presented. The technical challenges associated with generating and processing large amounts of data are also discussed.
                Cover page: A direct electron detector for time-resolved MeV electron microscopy
                • Article
                Lawrence Berkeley National Laboratory (2008)
                  Cover page: Rad-hard Luminosity Monitoring for the LHC
                  • Article
                  LBL Publications (2003)

                  The LHC beam luminosity monitor is based on the following principle. The neutrals that originate in LHC at every PP interaction create showers in the absorbers placed in front of the cryogenic separation dipoles. The shower energy, as it can be measured by suitable detectors in the absorbers is proportional to the number of neutral particles and, therefore, to the luminosity. This principle lends itself to a luminosity measurement on a bunch-by-bunch basis. However, detector and front-end electronics must comply with extremely stringent requirements. To make the bunch-by-bunch measurement feasible, their speed of operation must match the 40 MHz bunch repetition rate of LHC. Besides, in the actual operation the detector must stand extremely high radiation doses. The front-end electronics, to survive, must be located at some distance from the region of high radiation field, which means that a properly terminated, low-noise, cable connection is needed between detector and front-end electronics. After briefly reviewing the solutions that have been adopted for the detector and the front-end electronics and the results that have been obtained so far in tests on the beam, the latest version of the instrument in describe in detail. It will be shown how a clever detector design, a suitable front-end conception based on the use of a "cold resistance" cable termination and a careful low-noise design, along with the use of an effective deconvolution algorithm, make the luminosity measurement possible on a bunch-by-bunch basis at the LHC bunch repetition rates.

                    Cover page: The readout of the LHC beam luminosity monitor: Accurate shower energy measurements at a 40 MHz repetition rate
                    • Article
                    Lawrence Berkeley National Laboratory (2003)

                    We report on development of a new storage ring operations tool for measurement of longitudinal beam density profile. The technique mixes synchrotron light with light from a mode locked solid-state laser oscillator in a non-linear crystal and detects the up-converted radiation with a photo-multiplier. The laser is phase locked to the storage ring RF system. The laser choices available for repetition frequency, pulse length and phase modulation give a very wide range of options for matching the bunch configuration of particular storage rings. Progress in the technology of solid-state lasers ensures this system can be made robust for routine use in storage ring operations. A very large number of important applications are possible including measurement of the fraction of untrapped particles prior to acceleration, the population of particles in the nominally unfilled RF buckets in a bunch train ("ghost bunches"), longitudinal tails, the diffusion of particles into the beam abort gap and the normal bunch parameters of longitudinal shape and intensity. We are currently investigating application to two devices: (1) the 1.9 GeV ALS electron storage ring at LBNL with 328 RF buckets, 2ns bucket spacing, 276 nominally filled bunches, 15-30ps rms bunch length and (2) the 7 TeV LHC proton collider under construction at CERN with 35,640 RF buckets, 2.5 ns bucket spacing, 2,808 nominally filled bunches, 280-620 ps rms bunch length. A proof of principle experiment is being conducted on ALS. The results of the ALS experiment and detailed analyses of the application to LHC and its requirements are described.

                      Cover page: Development of a longitudinal density monitor for storage rings
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