A discriminator circuit uses dual current sources charging a capacitor to produce an output timing edge a fixed time after the starting corner of the input pulse, nearly independent of risetime and threshold setting. Performance with artificial and real pulses in the microsecond range is described. Background Obtaining a good timing information from slow-rising pulses is an old problem in pulse...

Progress made in the development of a miniature real-time volumetric ultrasound imaging system is presented. This system is targeted for use in a 5-mm endoscopic channel and will provide real-time, 30-mm deep, volumetric images. It is being developed as a clinically useful device, to demonstrate a means of integrating the front-end electronics with the transducer array, and to demonstrate the a...

By grounding the usual inputs of a 733 amplifier chip and driving one of the gain-control pins, one obtains a common-base input stage with an input impedance of about 20 ohms. This can be used as an inexpensive current-division preamp and, in large multichannel systems, will probably not limit the performance. In the current-division method of coordinate measurement one observes the (integrated...

Introduction High-field arrays with large numbers of coils require preamplifiers located close to the coils to minimize SNR losses incurred in cables. The design of low-noise preamplifiers for high-field MRI must thus ensure there is no performance degradation due to the presence or orientation of high magnetic fields. Preamplifier scattering (S) parameters have been known to vary with B0 field...

We describe a precision preamplifier and analog-to-digital ~AD! converter system for use with infrared focal plane arrays. The system uses a correlated double sampling integrated circuit which performs an analog subtraction of each full pixel level from its respective reset level prior to digitization by a 14-bit AD converter; this process is also known as ‘‘delta-reset’’ sampling. The system w...

New requirements on optical receivers are being driven by the rapid expansion of optical communications beyond traditional fiber-optic links. This thesis discusses the design of transimpedance amplifiers that are used in the preamplifier stage of optical receivers. The three specific requirements that are addressed here are a wide dynamic range, ambient light rejection, and low-voltage operatio...

We report the integration of a hybrid silicon evanescent waveguide photodetector with a hybrid silicon evanescent optical amplifier. The device operates at 1550 nm with a responsivity of 5.7 A/W and a receiver sensitivity of -17.5 dBm at 2.5 Gb/s. The transition between the passive silicon waveguide and the hybrid waveguide of the amplifier is tapered to increase coupling efficiency and to mini...

In recent years, there is an ever-growing demand for low-power and low-noise mixed signal integrated circuits for applications such as portable medical systems. A high level of system integration is required to implement bio-potential system with mixed signal circuits. The most commonly observed bio-potentials used for medical diagnoses are monitored non-invasively with electrodes placed on the...

A low-cost Commercial-Off-The-Shelf (COTS) 4H-SiC 0.06 mm2 UV p-n photodiode was coupled to a low-noise charge-sensitive preamplifier and used as photon counting X-ray spectrometer. The photodiode/spectrometer was investigated at X-ray energies from 4.95 keV to 21.17 keV: a Mo cathode X-ray tube was used to fluoresce eight high-purity metal foils to produce characteristic X-ray emission lines w...

An optimum algorithm to find interaction positions of a γ-ray in a Ge-detector is being investigated by analyzing pulse shapes of the Ge-detector VEGA [1, 2]. The VEGA detector consists of four Ge crystals forming like a four leaf clover. Each crystal has four electric segmentations in radial quarters. A collection time of electron and hole (eh) depends on their drift length, therefore the slop...