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Active RF Devices, Circuits and Systems Seminar

Date 12-12 Sept. 2011

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Displaying Results 1 - 13 of 13
  • Front cover

    Publication Year: 2011 , Page(s): c1
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  • Contents

    Publication Year: 2011 , Page(s): 3 - 4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (100 KB)  

    The following topics are dealt with: active RF devices; RF circuits; and microwave technology network. View full abstract»

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  • 40–70 GHz 13 Gbps 1-dB loss SPST and SPDT differential switches in 0.35 μm SiGe technology

    Publication Year: 2011 , Page(s): 11 - 15
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (255 KB)  

    This paper presents the design and characterization of ultrafast wideband low-loss single-pole single-throw (SPST) and single-pole double-throw (SPDT) differential switches. The SPDT switch exhibits insertion loss of lower than 1.25 dB from 42 to 70 GHz and isolation of better than 20 dB from 40 to 65 GHz. Similar low-loss and broadband characteristics are also observed from the measured SPST switch. The proposed switch topologies adopting current-steering technique and implemented in 0.35 μm SiGe bipolar technology result in a switching time of only 75 ps. This suggests a maximum switching speed of 13 Gbps, the fastest ever reported at V-band. View full abstract»

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  • Ku band LC-active 90nm CMOS VCO

    Publication Year: 2011 , Page(s): 17 - 26
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (602 KB)  

    A novel 13-GHz LC-active VCO has been implemented in 90nm CMOS technology by ST-Microelectronics. The VCO consists of two complementary cross-coupled pairs, an active LC tank implemented by means of a differential high-Q low-noise active inductor and two p-MOSFET varicaps, and an output buffer stage. The VCO provides a sinusoidal signal with amplitude of -11.3 dBm at 12.72 GHz. The measured phase noise amounts to -105.25 dBc/Hz at 1-MHz frequency offset. The VCO core and the active inductor have a current consumption of 700 μA and 1.8 mA, respectively, from a 1.2-V power supply. View full abstract»

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  • Broadband Gm-boosted differential HBT doublers with transformer balun

    Publication Year: 2011 , Page(s): 29 - 32
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (215 KB)  

    Broadband monolithic InGaP HBT frequency doublers for K-Band application have been developed. The designs employ a Gm-boosted differential common-base configuration using either capacitive or transformer-based coupling between base and emitters. The design with cross-coupled capacitors presents a fundamental rejection better than 20 dB over a 100% 3dB bandwidth, extending from 6-18 GHz. The transformer-coupled design has about 15dB fundamental rejection over a slightly narrower bandwidth extending from 7-16 GHz. Both doublers have conversion gain peaking at more than -0.8dB and output power more than 13 dBm. View full abstract»

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  • Experimental study of a highly linear amplifier using negative impedance compensation technique

    Publication Year: 2011 , Page(s): 35 - 43
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    negative impedance compensation is introduced. The principle of the technique is demonstrated by using a transistor-level prototype circuit with the HFA3127 ultra high frequency transistor arrays. The simulated and measured results show that high linearity (8dB improved IMD3 and 6dB improved OIP3) and high gain accuracy (up to 28%) can be achieved with the proposed technique. View full abstract»

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  • Validation of load-independent X-parameters® formulation for use in analytical circuit design

    Publication Year: 2011 , Page(s): 47 - 50
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (181 KB)  

    Recently analytical behavioral model formulation based on the PHD model has been introduced and successfully used to describe the nonlinear behavior of transistors and components [1-3]. The next important advance would be to utilize this formulation, constraint to load-independent X parameters, to enable analytical non-linear microwave circuit design procedures. For this purpose, in this paper a blind iterative process is presented and validated in order to obtain the appropriate load independent X parameters, focused around the chosen optimum impedance condition, necessary to enable accurate analytical non-linear circuit design to be undertaken. View full abstract»

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  • A threshold detection circuit using 90nm CMOS technology for TR-UWB receivers

    Publication Year: 2011 , Page(s): 53 - 57
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (65 KB)  

    This paper presents a threshold detection circuit with an adjustable detection window designed in IBM 90nm CMOS technology. Together with a RF multiplier, it realizes the back-end section of a transmitted reference ultra wideband receiver, which is yet to be reported in literature. The comparator section uses an operational trans-conductance amplifier core and avoids the use of sample and hold and control voltage generator circuits which reduces the electronic overhead needed for the architecture. The design is tested at a bit rate of 0.1~2.0 Gbps and the decision circuit consumes 9.14 mW power from a 1.2 V bias supply with a maximum speed to power ratio of 218.8GHz/W. When compared against other reported comparators, the detection circuit shows improved performance in terms of speed and power dissipation. View full abstract»

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  • Investigation of transformers' turn ratios and design procedure for an aperture coupled slot antenna

    Publication Year: 2011 , Page(s): 61 - 65
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (138 KB)  

    An aperture coupled antenna consists of feed, slot, and a radiation patch. The feed is normally a microstrip line with the slot etched in the ground plane and the radiating patch is located above the ground plane. To obtain maximum power transfer the microstrip line is orientated at right angle to the slot to obtain tight coupling. It is shown by Pozar that the patch and the slot modelled as two transmission lines connected in parallel produces a series impedance on the microstrip line. In the equivalent circuit of this antenna, the coupling between the microstrip line and the slot line is modelled as a transformer by a turn ratio nf. The coupling between the slot and the patch is modelled as a transformer by a turn ratio np. Initially derived equations for nf for finite lengths of the slot obtained by different researchers are reviewed and shown that they do not agree. To investigate this turn ratio the microstrip line and slot structure is modelled using CST software while the equivalent circuit of this structure is modelled using AWR software. For different lengths of the slots the series impedance Z on the feed line is obtained from the S21 parameter. The turn ratio in the equivalent circuit is tuned for the lengths of slots to obtain the value of the S21 parameter. Then the turn ratio of the transformer modelling the coupling between the slot line and the patch is also investigated. The antenna for both models has several interdependent design parameters so that an analytical design process is very difficult to implement. From the investigation carried out a design procedure for the antenna is proposed which is used to design the antenna for a frequency 2 GHz. The designed antenna is modelled using CST and AWR software and a good agreement has been obtained f View full abstract»

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  • Novel methods of killing bacteria using RF devices and conducting polymers

    Publication Year: 2011 , Page(s): 69 - 72
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (119 KB)  

    This paper will demonstrate plans for a new approach to combating device-related infection using RF circuits to test the effects of electric current against bacteria on the surfaces of conducting polymers. An electrically modified bacterial flow device has been designed incorporating inert platinum electrodes and a range of intrinsically conducting polymers and conducting composite samples to assess the impact of a range of RF frequencies and current intensities on a number of infectious hospital pathogens. View full abstract»

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  • Modelling of losses in load harmonic networks of high efficiency class E power amplifiers

    Publication Year: 2011 , Page(s): 75 - 79
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (65 KB)  

    To obtain high efficiency of dc to ac power conversion in an amplifier, it is necessary to decrease the power dissipation in the active device by ensuring that, the overlap of the voltage and current waveforms at the output terminals of the active device is minimized. This reduction of overlap is obtained by using load harmonic networks to shape the above waveforms at the output terminals of the active device. In the three common classes of high efficiency power amplifiers (PAs) (F. F-1 and E), this shaping is obtained by attenuating different harmonics of the waveforms by using load harmonic networks. For the class E amplifier a capacitance is placed across at the output terminals of the active device. This is to ensure that the output voltage is delayed until the active device is turned `off' and the output voltage reaches its minimum value with a slow turn `on'. If this device is driven hard 'on' and 'off' to obtain high efficiency it is shown that the input impedance must be very high at the harmonic frequencies. At the design frequency the required input impedance depends on the value of the above capacitance. Ideal lossless transmission lines (Tlines) are used in the initial design of harmonic networks for high efficiency power amplifiers and then practically realised using microstrip lines (Mlines). As the metal and substrate losses in Mlines are normally expressed in terms of attenuation constants, these losses are difficult determine as they require solutions of complex mathematical equations. In this paper to reduce such complex analysis the losses in an Mlines are modelled as a Tlines in series a resistance. A novel method is proposed to determine this resistance as a function of the length of the Mlines which is realised using inexpensive PCB FR4 substrate. Then for the above two line models, ha View full abstract»

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  • Design a V-band 4×4 Butler matrix for switched beam-forming operation

    Publication Year: 2011 , Page(s): 83 - 86
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (594 KB)  

    A compact V-band 4×4 Butler matrix, using 0.35 μm SiGe bipolar process, is proposed in this work. This design exhibits an average insertion loss of 3 dB with amplitude variation less than 1.5 dB and an average phase imbalance of less than 10 degrees from 55 GHz to 65 GHz. The chip area is only 0.5×0.9 mm2 including all pads. The SiGe Butler matrix is an excellent candidate for MIMO systems and applied in high data-rate communications. View full abstract»

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  • A MMIC double balanced diode ring mixer in GaAs

    Publication Year: 2011 , Page(s): 89 - 92
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (238 KB)  

    This paper presents a monolithic microwave integrated circuit (MMIC) double balanced diode ring mixer. This chip fabricated in the 0.15 μm pHEMT GaAs process which is offered by WIN Semiconductor. Spiral structure of Marchand balun is used to minimize the chip's size. This mixer design achieves a low conversion loss of 5 to 6 dB and high LO-RF isolation of average 45 dB over the RF/LO bandwidth which is 15-25 GHz and a DC-2 GHz IF. This mixer also obtains good linearity with IIP3 of more than 20 dBm. The chip's size included build in Marchand balun is around 0.75 mm2. View full abstract»

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