Novel method of dro frequency tuning with varactor diode

1990 ◽  
Vol 26 (15) ◽  
pp. 1162 ◽  
Author(s):  
N. Popović
Keyword(s):  
Frequency Tuning ◽  
Varactor Diode ◽  
Novel Method

An L-band SiGe HBT differential amplifier with frequency and rejection-level tunable, multiple stopband

2009 ◽  
Vol 1 (4) ◽  
pp. 285-292 ◽  
Author(s):  
Masaki Shirata ◽  
Toshio Shinohara ◽  
Minoru Sato ◽  
Yasushi Itoh
Keyword(s):  
Bias Voltage ◽  
Frequency Tuning ◽  
Differential Amplifier ◽  
Tank Circuit ◽  
Band Frequency ◽  
Varactor Diode ◽  
Sige Hbt ◽  
Active Load ◽  
Rejection Level ◽  
L Band

An L-band frequency and rejection-level tunable SiGe HBT differential amplifier with dual stopband is presented. To achieve frequency and rejection-level tunable performance, dual LCR-tank circuit with an active load is incorporated into the design of the series feedback loops of the differential amplifier. The active load consists of a varactor diode represented as a variable C and a common-emitter transistor represented as a variable R. The frequency and rejection level can be tuned independently by controlling a cathode bias voltage of the varactor diode or a base bias voltage of the transistor. The implemented 0.35 μm SiGe HBT amplifier with dual stopband demonstrates a frequency tuning of 0.53–1.16 GHz and a rejection-level variation up to 9.5 dB. The input and output return losses are better than 17.5 and 11 dB over 0.2–1.5 GHz, respectively. The measured P1dB is+3 dBm and IIP3 is 0 dBm with Vcc = 6 V and Ic = 8 mA.

Natural Frequency Tuning Using Structural Patches

2005 ◽  
Vol 127 (1) ◽  
pp. 28-35 ◽  
Author(s):  
P. W. Wang ◽  
C. C. Cheng
Keyword(s):  
Natural Frequency ◽  
Natural Frequencies ◽  
Frequency Tuning ◽  
Search Method ◽  
Optimal Search ◽  
Novel Method ◽  
Host Structure

A novel method for shifting the natural frequencies of a structure to specific values using structural patches is introduced. When a host structure is bonded with multiple structural patches, its natural frequencies can be shifted to the desired values by tuning the patch thickness and the patch location on the host structure. These parameters can be analytically determined using the methodology proposed in this paper. The time consuming process produced using the traditional optimal search method is thereby avoided. The results show that multiple natural frequencies can be changed simultaneously to the desired values. The number of natural frequencies shifted requires using the same number of structural patch pairs. Several examples using this technique are demonstrated and the results are experimentally validated.

scholarly journals Frequency tuning varactor-loaded reconfigurable antenna for m-WiMAX and WLAN applications

2019 ◽  
Vol 13 (2) ◽  
pp. 779
Author(s):  
S. M. Shah ◽  
K. Hamdan ◽  
Z. Z. Abidin ◽  
F. C. Seman ◽  
S. A. Hamzah ◽  
...  
Keyword(s):  
Patch Antenna ◽  
Frequency Tuning ◽  
Microstrip Patch Antenna ◽  
Dual Band ◽  
Reconfigurable Antenna ◽  
Resonant Frequencies ◽  
Varactor Diode ◽  
Microstrip Patch ◽  
Tunable Device ◽  
Tan Δ

A design approach for a microstrip patch antenna to achieve the reconfigurable dual-band operation with a tunable device is presented in this work. The approach uses a BB833 varactor diode in the middle of a slotted patch antenna which which is able to produce dual-band resonant frequencies. The reconfigurable antenna is designed and simulated in CST Microwave Studio® software and is later, fabricated on a FR-4 substrate with a dielectric constant,  of 4.5, loss tangent, tan δ of 0.019 and thickness, h of 1.6 mm. By changing the DC voltages of the varactor diode, different capacitance values of the varactor diode are obtained which dictate the specific resonant frequencies. From the simulation results, the capacitance value of 0.5 pF with a bias voltage of 2.0 V is chosen as it produces the required dual-band resonant frequencies at 3.38 GHz and 5.37 GHz for desired applications in the m-WiMAX and WLAN bands.

The removal and morphology of intact biofilms from implanted venous access devices

1995 ◽  
Vol 53 ◽  
pp. 1020-1021
Author(s):  
M.A. Gregory ◽  
G.P. Hadley
Keyword(s):  
Patient Selection ◽  
Surgical Oncology ◽  
Venous Access ◽  
Common Procedure ◽  
Indwelling Catheters ◽  
Careful Patient ◽  
Novel Method ◽  
The Subject ◽  
Vascular Catheters ◽  
Venous Access Devices

The insertion of implanted venous access systems for children undergoing prolonged courses of chemotherapy has become a common procedure in pediatric surgical oncology. While not permanently implanted, the devices are expected to remain functional until cure of the primary disease is assured. Despite careful patient selection and standardised insertion and access techniques, some devices fail. The most commonly encountered problems are colonisation of the device with bacteria and catheter occlusion. Both of these difficulties relate to the development of a biofilm within the port and catheter. The morphology and evolution of biofilms in indwelling vascular catheters is the subject of ongoing investigation. To date, however, such investigations have been confined to the examination of fragments of biofilm scraped or sonicated from sections of catheter. This report describes a novel method for the extraction of intact biofilms from indwelling catheters.15 children with Wilm’s tumour and who had received venous implants were studied. Catheters were removed because of infection (n=6) or electively at the end of chemotherapy.

Longitudinal Changes in Individual BrainAGE in Healthy Aging, Mild Cognitive Impairment, and Alzheimer’s Disease

GeroPsych ◽  
2012 ◽  
Vol 25 (4) ◽  
pp. 235-245 ◽  
Author(s):  
Katja Franke ◽  
Christian Gaser
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Healthy Aging ◽  
Brain Aging ◽  
Elderly Subjects ◽  
Additional Increase ◽  
Longitudinal Changes ◽  
Novel Method ◽  
The Brain

We recently proposed a novel method that aggregates the multidimensional aging pattern across the brain to a single value. This method proved to provide stable and reliable estimates of brain aging – even across different scanners. While investigating longitudinal changes in BrainAGE in about 400 elderly subjects, we discovered that patients with Alzheimer’s disease and subjects who had converted to AD within 3 years showed accelerated brain atrophy by +6 years at baseline. An additional increase in BrainAGE accumulated to a score of about +9 years during follow-up. Accelerated brain aging was related to prospective cognitive decline and disease severity. In conclusion, the BrainAGE framework indicates discrepancies in brain aging and could thus serve as an indicator for cognitive functioning in the future.

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