S. van Waasen

Fully integrated distributed power amplifier in CMOS technology, optimized for UWB transmitters

A power amplifier (PA) using the distributed amplifier technique for the ultra wideband (UWB) standard is presented. The amplifier is fabricated in a standard 0.13 /spl mu/m CMOS technology and comes with on-chip biasing circuitry and a non-distributed input stage. Measurement results are given for a chip-on-board module to take any influence of product assembly into account. It achieves a transmission coefficient S/sub 21/ = 17 dB, a corner frequency of f/sub c/ = 8 GHz and a 1 dB compression point of A/sub 1dB/ = 3.5 dBm. The output impedance is matched to 50 /spl Omega/ so that external matching circuitry can be omitted. With these features, it is customized to be integrated with other building blocks to a fully integrated CMOS UWB transmitter product.

A fully integrated CMOS frequency synthesizer for Bluetooth

A low power, fully integrated 2.4 GHz fractional-N frequency synthesizer for Bluetooth in a 0.25 /spl mu/m CMOS technology is presented. The complete synthesizer, including a fully integrated VCO, consumes 22 mA from a 2.5 V supply. The integrated VCO reaches a phase noise of -133 dBc/Hz at 3 MHz. The synthesizer is designed for a direct /spl Sigma//spl Delta/-modulation of the PLL.

Broadband EIT borehole measurements with high phase accuracy using numerical corrections of electromagnetic coupling effects

Electrical impedance tomography (EIT) is gaining importance in the field of geophysics and there is increasing interest for accurate borehole EIT measurements in a broad frequency range (mHz to kHz) in order to study subsurface properties. To characterize weakly polarizable soils and sediments with EIT, high phase accuracy is required. Typically, long electrode cables are used for borehole measurements. However, this may lead to undesired electromagnetic coupling effects associated with the inductive coupling between the double wire pairs for current injection and potential measurement and the capacitive coupling between the electrically conductive shield of the cable and the electrically conductive environment surrounding the electrode cables. Depending on the electrical properties of the subsurface and the measured transfer impedances, both coupling effects can cause large phase errors that have typically limited the frequency bandwidth of field EIT measurements to the mHz to Hz range. The aim of this paper is to develop numerical corrections for these phase errors. To this end, the inductive coupling effect was modeled using electronic circuit models, and the capacitive coupling effect was modeled by integrating discrete capacitances in the electrical forward model describing the EIT measurement process. The correction methods were successfully verified with measurements under controlled conditions in a water-filled rain barrel, where a high phase accuracy of 0.8 mrad in the frequency range up to 10 kHz was achieved. The corrections were also applied to field EIT measurements made using a 25 m long EIT borehole chain with eight electrodes and an electrode separation of 1 m. The results of a 1D inversion of these measurements showed that the correction methods increased the measurement accuracy considerably. It was concluded that the proposed correction methods enlarge the bandwidth of the field EIT measurement system, and that accurate EIT measurements can now be made in the mHz to kHz frequency range. This increased accuracy in the kHz range will allow a more accurate field characterization of the complex electrical conductivity of soils and sediments, which may lead to the improved estimation of saturated hydraulic conductivity from electrical properties. Although the correction methods have been developed for a custom-made EIT system, they also have potential to improve the phase accuracy of EIT measurements made with commercial systems relying on multicore cables.

Fast Charge to Pulse Width Converter for Monolith PET Detector

Currently both preclinical and clinical PET systems are built with pixilated, optically isolated scintillators. The use of optical isolators limits the achievable packing fraction for designs that use small crystals. No optical isolation is necessary in a monolithic scintillation crystal design hence the sensitivity is increased. The light distribution created by a high energy interaction in a monolithic scintillator can be readout by a SiPM-array to determine the 3-D position of the interaction. We have developed a digital pulse width modulation readout circuit that is able to readout many densely packed SiPM-arrays connected to monolithic scintillators. A monolithic scintillation detector requires simultaneous acquisition of the light distribution on multiple sensors unlike in a one-to-one optically isolated pixelated configuration. Therefore, pulse width modulation can reduce the readout complexity of the monolithic scintillation detector. The circuit gives an output signal with a pulse width linear to the incoming charge. Therefore, the circuit provides both timing and intensity information using just one digital line per channel. The charge to pulse-width conversion ratio of the circuit is adjustable (e.g., 33 ns/pC). The trigger jitters σ 41.2 ps between two channels. The PCB offers 8 channels and comes with additional features: The gain variation of a SiPM is compensated over a large temperature range by controlling the bias voltage. We measured from 15°C to 42°C, here it can bring the variation of a SiPM in gain from -21 ns/ °C to +3.8 ns/ °C or stabilizes the variation of the energy resolution between 18 and 20%.

An L-band receiver-front-end-architecture using adaptive Q-enhancement techniques in 65nm CMOS as enabler for single-SAW GPS receivers

A GPS receiver front-end achieves high dynamic input range by using Q-enhancement circuitry. In mobile phone environments the Q of the LNA is automatically increased, improving blocker performance by 11.3dB. The area is 1.9mm2 fabricated in a 65nm CMOS process without RF options and requires 25mA from a 1.3V supply with a system NF of 1.5dB.

Fully integrated CMOS GPS receiver for system-on-chip solutions

A CMOS receiver for the Global Positioning System (GPS) is presented. It is designed in a 0.13mum standard CMOS process and is fully integrated for the needs of a system-on-chip (SoC) solution for GPS and assisted GPS (A-GPS). It provides the needed frequency conversion, gain and filtering for GPS signals without any other external components than those required for matching and decoupling. The receiver includes the local oscillator (LO) signal generation and all needed supply voltage regulators. The achieved noise figure (NF) of the receiver is 1.8dB, including losses of external filtering for blocking requirements

Simulation studies of optical photons in monolithic block scintillators

The interest in PET detectors with monolithic block scintillators is growing. In order to obtain high spatial resolutions dedicated positioning algorithms are required. But even an ideal algorithm can only deliver information which is provided by the detector. In this simulation study we investigated the light distribution on one surface of cuboid LSO scintillators of different size. Scintillators with a large aspect ratio (small footprint and large height) showed significant position information only for a minimum interaction depth of the gamma particle. The results allow a quantitative estimate for a useful aspect ratio.

Phase correction of electromagnetic coupling effects in cross-borehole EIT measurements

Borehole EIT measurements in a broad frequency range (mHz to kHz) are used to study subsurface geophysical properties. However, accurate measurements have long been difficult because the required long electric cables introduce undesired inductive and capacitive coupling effects. Recently, it has been shown that such effects can successfully be corrected in the case of single-borehole measurements. The aim of this paper is to extend the previously developed correction procedure for inductive coupling during EIT measurements in a single borehole to cross-borehole EIT measurements with multiple borehole electrode chains. In order to accelerate and simplify the previously developed correction procedure for inductive coupling, a pole–pole matrix of mutual inductances is defined. This consists of the inductances of each individual chain obtained from calibration measurements and the inductances between two chains calculated from the known cable positions using numerical modelling. The new correction procedure is successfully verified with measurements in a water-filled pool under controlled conditions where the errors introduced by capacitive coupling were well-defined and could be estimated by FEM forward modelling. In addition, EIT field measurements demonstrate that the correction methods increase the phase accuracy considerably. Overall, the phase accuracy of cross-hole EIT measurements after correction of inductive and capacitive coupling is improved to better than 1 mrad up to a frequency of 1 kHz, which substantially improves our ability to characterize the frequency-dependent complex electrical resistivity of weakly polarizable soils and sediments in situ.

PhenoPET: A dedicated PET scanner for plant research based on digital SiPMs (DPCs)

In the framework of the German Plant Phenotyping Network (DPPN) we developed a novel PET scanner for imaging plants and crops. The observation of the carbon transport within the plant becomes possible by using 11CO2 as PET tracer. The use of the rather short living isotope C-11 asks for a scanner with high dynamic range. That means fast timing and high data rates are important features which let us choose the Philips Digital Photon Counter (DPC) as photo detector. Due to the fast photo detectors and the special crystal matrix arrangement the system will allow measurements with rather high activities. We could measure a coincidence resolution time of ~ 250 ps FWHM between two detector elements. This opens the opportunity to employ time-of-flight information for the first time on a PET scanner of this size. This paper presents very first results from a prototype single-ring system with a FOV of 18 cm diameter and 6.5 cm axial height.

Read-out electronics for digital silicon photomultiplier modules

This work has its focus on the development of fast read-out electronics for digital silicon photomultipliers (dSiPM -called Digital Photon Counter (DPC) by Philips).