Ilona Rolfes

A highly linear frequency ramp generator based on a fractional divider phase-locked-loop

A highly linear analog frequency ramp generator based on a fractional divider concept is presented. The frequency ramp linearity achievable in this fractional phase-locked-loop configuration is better than 10/sup -4/. This value is revealed by numerical simulations as well as by measurements performed. With a prototype synthesizer implemented in a FMCW-radar system suitable for distance and velocity measurements.

Multiport method for the measurement of the scattering parameters of N-ports

The multiport method for the precise measurement of the scattering parameters of N-port devices with a two-port vector network analyzer (VNA) is presented. The scattering parameters of an N port cannot be measured directly with a two-port VNA if N>2. Only the scattering parameters of all two-port combinations of the device-under-test (DUT) are measurable. Thereby, the measured two-port scattering parameters strongly depend on the external terminations of the DUTs ports, which are not connected to the VNA during the measurements. In order to eliminate the influences of these external possibly reflective terminations, an error correction has to be performed. In comparison to known correction methods, the multiport method has some advantages. Firstly, the external terminations can be chosen arbitrarily, i.e., short and open circuits are realizable as long as the topology of the DUT allows it. Secondly, the terminations, except for one, can be unknown, leading to a reduction of the inconsistency problem caused by erroneous data of the external terminations, which is also known from the calibration of VNAs with completely known calibration standards. The good performance of the multiport method is shown by measured results.

The multipole resonance probe: characterization of a prototype

The multipole resonance probe (MRP) was recently proposed as an economical and industry compatible plasma diagnostic device (Lapke et al 2008 Appl. Phys. Lett. 93 051502). This communication reports the experimental characterization of a first MRP prototype in an inductively coupled argon/nitrogen plasma at 10?Pa. The behavior of the device follows the predictions of both an analytical model and a numerical simulation. The obtained electron densities are in excellent agreement with the results of Langmuir probe measurements.

Inductorless Low-Voltage and Low-Power Wideband Mixer for Multistandard Receivers

This paper presents the design and implementation of a low power wideband mixer for multistandard receivers, covering global system for mobile communications, universal mobile telecommunications system, wireless local area network, Bluetooth, and ultra-wideband. The circuit topology is based on the folded technique with a current reuse shunt feedback RF input stage operating at a low supply voltage of 1 V. The mixer offers a peak gain of 12.8 dB, a 3-dB bandwidth from 1 to 10.5 GHz, and a minimum double-sideband noise figure of 7.6 dB. The input referred compression point is better than -15 dBm with an output referred intercept point of better than 5.75 dBm over the entire bandwidth. The mixer circuit was fabricated in a 65-nm standard CMOS process and draws 5 mA of dc current, leading to a power dissipation of only 5 mW. Gain and noise performance can be further increased when operating at nominal supply voltage of 1.2 V at the expense of an increasing power dissipation.

The Multipole Resonance Probe: Progression and Evaluation of a Process Compatible Plasma Sensor

A robust and sensitive plasma sensor, the multipole resonance probe (MRP), and its process compatibility are presented and discussed in this paper. Based on its innovative concept and simple model describing the system “probe-plasma”, three steps of development are introduced. 3D electromagnetic field simulations are applied as an indispensable tool for an economical and efficient investigation and optimization of different sensor layouts. Independent of the chosen sensor design, a developed pulse-based measurement device yields an economical signal generation and evaluation. Electron density profiles, determined with the MRP and the pulse-based system utilized in a capacitive coupled plasma, confirm and demonstrate the simulation results and the measurement concept, respectively.

Inductorless 1–10.5 GHz wideband LNA for multistandard applications

This article presents the design of a fully integrated inductorless LNA for wireless applications including WLAN, Bluetooth and UWB. The circuit was fabricated in 65nm CMOS technology and operates at a supply voltage of 1.2 V. The two-stage design is comprised of a current reuse shunt feedback input stage followed by a differential pair, incorporating an active inductor load to compensate the gain roll-off. The circuit exhibits a peak gain of 16.5 dB, while the 3-dB bandwidth as well as the input and output matching of better than −10 dB range from 1–10.5 GHz. The noise figure is kept below 5 dB within this frequency range, offering a minimum noise figure of 3.9 dB. The linearity in terms of P1dB, out and oIP3 offers nearly constant behavior with −5 dBm and 3 dBm respectively. The active area takes up only 0.021 mm2.

Compact directional UWB antenna with dielectric insert for radar distance measurements

A circular waveguide-fed UWB antenna for the frequency range from 8.5 to 10.5 GHz is presented, incorporating a dielectric insert mounted inside a short metallic excitation horn, yielding a significantly enlarged aperture efficiency compared to the same horn without dielectric insert and even to the theoretical limit of a conical horn antenna of infinite length having similar geometrical aperture restrictions. Regarding industrial radar level gauging, the maximum antenna dimensions are strictly limited due to standardized nozzle and flange diameters and thus compact directional antennas with low side lobe levels are needed allowing broadband radar operation and simultaneously suppressing signal distortions by unwanted scatterers. By utilizing a prototype setup of the proposed antenna, the anticipated performance gain is proved by measurement results validating the simulated characteristic antenna parameters as well as the improved radar distance measurement accuracy.

LRR-a self-calibration technique for the calibration of vector network analyzers

A new self-calibration procedure, the LRR method, for the calibration of vector network analyzers is presented. The calibration circuits consist of partly unknown standards, where L symbolizes a line element and R represents a symmetrical reflection standard. In contrast to the thru reflect line (TRL) method, which needs a line-standard with a different length than the other calibration standards, the calibration circuits of the LRR method are all of equal mechanical length. This is advantageous because the connectors of the vector network analyzer do not, thus, have to be placed at different distances from each other during calibration. In addition, the complexity of the test fixture can be reduced. The robust functionality of the LRR method is confirmed by measurements.

Determination of the delay spread of an indoor channel measurement campaign in the UHF band

This contribution deals with the determination of the delay spread of the indoor channel within a large exhibition hall. The results are of special interest to Programme Making and Special Event applications, intending to operate in this typical scenario, and are representative for other applications within the entire UHF range. To determine the delay spread an ultra-wideband measurement campaign is carried out. Both the small scale as well as the large scale setup of the campaign are introduced in this paper.

Compact Unfocused Antenna Setup for X-Band Free-Space Dielectric Measurements Based on Line-Network-Network Calibration Method

This paper presents a compact free-space measurement system for the characterization of dielectric materials within the X-band based on the line-network-network (LNN) calibration method. Using a pair of dielectric-filled horn antennas with enhanced directivity, the setup exhibits a total length of 250 mm between the antenna apertures and is suitable for measurements of planar samples with transverse dimensions equal to or greater than 250 mm×250 mm. Based on 3-D field simulations and measurements, the assumptions of plane wave incidence on the sample and negligible diffraction effects at the sample edges are investigated. The scattering parameters of the sample are obtained according to the LNN calibration method. Remaining multipath propagation effects caused by reflections at the antennas and their fixtures are filtered out via time gating. The complex permittivity is finally calculated from the transmission scattering parameter using the Newton-Raphson method. Results for exemplary dielectrics are in good accordance with reference values.