Informatics Publishing Limited

Kamaljeet Singh ¹, A. V. Nirmal ¹, S. V. Sharma ¹

Affiliations
1 Systems Engineering Group, ISRO Satellite Centre, IN

Abstract

Electrostatic bonding between glass and silicon is carried out in micro sensor devices to achieve higher bond strength thus eliminating the requirement of adhesives. This can also be useful in providing hermiticity and results in reliable operation of the micro sensor devices. Practically the sensor performance is prone to long term drift mainly due to process associated with the assembly and packaging. Bonding is the one of the critical process in micro sensor and generally sensor stability is dependent on this process along with other packaging material and methodology. Bond strength is one of the critical parameters to find out the quality of bond and the same is quantified and compared for different conditions. This article details electrostatic bonding process, various parameters responsible for the reliable bonding, modelling and characterization along with simple methodology to achieve higher bond strength.

Keywords

Bonding, Micro-Sensor, Anodic, Electrostatic, Sensor, Bond Strength.

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Kamaljeet Singh ¹, A. V. Nirmal ¹, S. V. Sharma ¹

Affiliations
1 Systems Engineering Group, ISRO Satellite Centre, Bangalore, IN

Abstract

The systematic evaluation of the link budget calculation for the satellite and terrestrial communication is presented in this article. Communication link between the satellite and earth station is dependent on various propagation and associated losses which are either constant or vary with weather conditions. Role of receiver noise, antenna pointing mechanism, atmospheric effects, slant height, interferences, bit error rate on the link margin are detailed in this article. Various equations for link budget calculation and a comparative table at various frequency bands are shown in this article which is useful for predicting link margin of LEO, GEO and Deep space missions. Tele-command, telemetry and ranging link margin at various frequencies are presented and budget analysis at Ka-band frequency performed.

Keywords

Link Budget, Margin, Atmospheric Effects, Noise, Propagation Losses, Uplink, Downlink.

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Kamaljeet Singh ¹, A. V. Nirmal ¹

Affiliations
1 Systems Engineering Group, U R Rao Satellite Centre, Bangalore, IN

Abstract

Satellite based communication either in GEO or LEO based system are prominently employed for voice, video, data communication. Demand of more traffic necessitates the data rate of satellite to be enhanced which can be implemented by the proper choice of modulation scheme. Presently ground systems are also wireless based which include direct broadcast satellite (DBS),television service, wireless local area networks (WLANs), global positioning satellite (GPS), radio-frequency identification systems which is either point-to-point or point-tomultipoint. Modern day communication systems are digital; based rather than analog to have better noise immunity. Further with the limited spectrum availability the choice of modulation scheme plays an important role for faithful transmission of the signal. The digital communication can be categorized as Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), Phase Shift Keying (PSK) whereas for higher bit data rate Phase Shift Keying (PSK) such as BPSK, QPSK and OQPSK are employed. This article overview of various modulation schemes which are employed in satellite communication apart from its selection criteria along with the concept of bit error rate.

Keywords

Modulation Scheme, Communication System, Noise, Radio-Frequency.

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Kamaljeet Singh ¹, A. V. Nirmal ¹

Affiliations
1 U R Rao Satellite Centre, Indian Space Research Organisation, IN

Abstract

The integration of RF circuits with CMOS on the same substrate is challenging and imposes lot of constraint in practical realization due to inherent losses associated with silicon Si substrate. Various mitigation techniques are proposed to overcome the same which are either process intensive or introduces multiple deleterious effects at RF frequencies. Polyimide is used both in microelectronics and MEMS industry as it can act both as a photo-resist and also having key dielectric properties. The processes presented with polyimide are standard and can be easily integratable with the existing CMOS processes. Fabrication steps and simulation study of the band pass filter topologies over polyimide are presented and the same are fabricated with the proposed process steps. Further this article details the modelling, theoretical aspects, various process steps and actual implementation with the realization of the band pass filter topology using the proposed methodology.

Keywords

Polyimide, Silicon, Radio Frequency, Modelling.

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K. Singh ¹, A. V. Nirmal ¹

Affiliations
1 System Engineering Group, U R Rao Satellite Centre, IN

Abstract

Planar transmission line on silicon substrate imposes certain challenges at higher frequencies and measurement of the same employing wafer probing techniques needs accurate characterization. Wafer measurement provides information related with the device performance which in turn helps to minimize parasitic related with package and assembly. Wafer probing at higher frequencies imposes certain challenges more so ever on silicon substrate. Silicon substrate due to semiconductor in nature is a lossy medium for radio frequencies and standard wafer is not suitable for the realization of RF circuits. Present article demonstrate realization of planar transmission line on high resistivity silicon substrate by employing thick oxide layer. Both simulated and measured results are presented in this article and the CPW line fabricated with the proposed process results in ~1dB loss with better than 12dB return loss at Ka-band. Measurement techniques for the line characterization are detailed in this article along with transmission line characterization at Ka-band.

Keywords

Wafer Probing, Testing, Measurement, Radio-Frequency.

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