Arash Sadeghfam

Electrically Tunable Bandpass Filter with Integrated Carrier Suppression for UHF RFID Systems

One of the most critical points in designing a RFID system based on the backscattering process is the limitations in the system dynamic resulting from the Tx-Rx-leakage, principally over the circulator and partly through environmental reflections. This signal can overshadow the modulated tag reply, which is generally at a maximum of only a few hundred kilohertz apart. This paper presents a novel patented hardware based solution, which combines the bandpass filtering of the operational channel required for a multi-reader environment with the suppression of the carrier leakage, leading to an improvement in the system dynamic of over 50 dB. Experimental results verifying the proposed architecture are presented. The relative bandwidth of the measured filter is under 0.03% as compared to the center frequency of 866.5 MHz, corresponding to the European RFID band.

Characterization and Optimization Technique for Microwave-Driven High-Intensity Discharge Lamps Using Hot

High-intensity discharge lamps can be driven by radio-frequency signals in the ISM frequency band at 2.45 GHz, using a matching network to transform the impedance of the plasma to the source impedance. To achieve an optimal operating condition, a good characterization of the lamp in terms of radio frequency equivalent circuits under operating conditions is necessary, enabling the design of an efficient matching network. This paper presents the characterization technique for such lamps and presents the design of the required matching network. For the characterization, a high-intensity discharge lamp was driven by a monofrequent large signal at 2.45 GHz, whereas a frequency sweep over 300 MHz was performed across this signal to measure so-called small-signal hot S-parameters using a vector network analyzer. These parameters are then used as an equivalent load in a circuit simulator to design an appropriate matching network. Using the measured data as a black-box model in the simulation results in a quick and efficient method to simulate and design efficient matching networks in spite of the complex plasma behavior. Furthermore, photometric analysis of high-intensity discharge lamps are carried out, comparing microwave operation to conventional operation.

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This paper presents a microplasma ignition at 2.45GHz for various applications as well as spark plugs, plasma beams, low and high pressure lamps by using a three stage impedance transformer. The presented transformation network generates a very high voltage. Using this network, plasma ignition and sustainment are possible under atmospheric pressure, low pressure or even under very high pressure conditions. It could be shown in different tests that this concept holds true for power levels varying between 10W to 200W, offering various advantages for a variety of plasma applications at 2.45GHz.

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A monolithic integrated filter with mode conversion and impedance transformation for GSM 900 is presented. Hereby, a so called rat-race inductor is utilized, replacing up to six conventional inductors and one transformer, resulting in a reduction in chip size by approximately 50 %. The rat-race inductor is handled theoretically and 3D-EM based simulations are carried out, verifying the proposed structures and expected results. A first wafer run is to be fabricated on Infineon Technologies P7MI semiconductor process. The insertion loss of the filter is as low as 2.3 dB accompanied by a phase imbalance of less than 5/spl deg/ and an amplitude imbalance of less than 0.5 dB.

Various applications and background of 10–200W 2.45GHz Microplasmas

This paper presents the description and theory of the novel amplitude-locked loop (ALL) circuit to support RF energy solutions as well as RF plasma and microwave heating applications. This analog control circuit includes scalar hot S-parameter measurements to lock to the best S11-value in the 2.45 GHz ISM band. The necessary architecture including a new amplitude discriminator circuit is presented in detail. The second part of the paper describes hardware solutions, one with discrete integrated circuits and the current solution, which is fully integrated in a patented C11N CMOS-IC. These ALL solutions were tested in low speed applications (e.g. lamps) and high speed systems (e.g. spark plugs). The measurement results of the ALL hardware solutions wind up this paper. These measurement results exemplify the very good quality of this novel amplitude-locked loop circuit for different dynamic loads.

Ultra compact multi-mode filter with novel rat-race inductor

The contemporary way to make telecommunication circuits is based on a differential approach, consisting of doubling the single-ended circuit. This results in a perfectly symmetrical structure with a doubled part count and twice the size. In this paper, a new design methodology based on coupled inductors is introduced, resulting in a part count for the differential circuit equalling that of the single-ended circuit with an almost unchanged chip area. At the same time, due to a higher magnetic flux, the quality factor of the new inductors is enhanced up to 40 % compared to a conventional inductor. To verify the proposed theory, experimental results of two semiconductor integrated circuits are presented, showing a very good agreement with the simulated results.