Mosfet-C Transimpedance Filters with Center Frequency Tunability Feature

Author(s):  
Bilgin Metin ◽  
Yasin Basaran ◽  
Norbert Herencsar ◽  
Mohammad Faseehuddin ◽  
Oguzhan Cicekoglu
2016 ◽  
Vol 9 (4) ◽  
pp. 765-772 ◽  
Author(s):  
Hamza Nachouane ◽  
Abdellah Najid ◽  
Abdelwahed Tribak ◽  
Fatima Riouch

This paper presents a simple reconfigurable bandpass filter switching from 2.4 to 5 GHz based on PIN diodes. The proposed filter is intended to add frequency-tunability to antenna systems used in cognitive radio applications. It consists of a bent connecting stub with two open-circuited quarter-wave stubs grounded via PIN diodes. By controlling the didoes states, the electrical length of the stubs can be switched from quarter-wave to half-wave and vice versa, so as to tune the filter center frequency. The proposed design approach consists of ensuring communication at 2.4 GHz while blocking the 5 GHz band in the ON state, whereas in the OFF state, the filter is intended to reject the 2.4 GHz band and passing the 5 GHz band. A prototype of the proposed filter is fabricated and measured to validate the proposed concept. Both simulated and measured results show a two-state filter with a wide tuning range from 2.4 to 5 GHz and a good stopband rejection level better than 40 dB. Moreover, a flat group delay of about 0.55–0.7 ns is achieved within the operating bandwidth in both states. The proposed filter is able to achieve simultaneous bandwidth and frequency control, showing an important tool to meet modern system requirements.


2013 ◽  
Vol E96.C (2) ◽  
pp. 192-196 ◽  
Author(s):  
Isao MOROHASHI ◽  
Yoshihisa IRIMAJIRI ◽  
Takahide SAKAMOTO ◽  
Tetsuya KAWANISHI ◽  
Motoaki YASUI ◽  
...  

Author(s):  
Shitesh Tiwari ◽  
Sumant Katiyal ◽  
Parag Parandkar

Voltage Controlled Oscillator (VCO) is an integral component of most of the receivers such as GSM, GPS etc. As name indicates, oscillation is controlled by varying the voltage at the capacitor of LC tank. By varying the voltage, VCO can generate variable frequency of oscillation. Different VCO Parameters are contrasted on the basis of phase noise, tuning range, power consumption and FOM. Out of these phase noise is dependent on quality factor, power consumption, oscillation frequency and current. So, design of LC VCO at low power, low phase noise can be obtained with low bias current at low voltage.  Nanosize transistors are also contributes towards low phase noise. This paper demonstrates the design of low phase noise LC VCO with 4.89 GHz tuning range from 7.33-11.22 GHz with center frequency at 7 GHz. The design uses 32nm technology with tuning voltage of 0-1.2 V. A very effective Phase noise of -114 dBc / Hz is obtained with FOM of -181 dBc/Hz. The proposed work has been compared with five peer LC VCO designs working at higher feature sizes and outcome of this performance comparison dictates that the proposed work working at better 32 nm technology outperformed amongst others in terms of achieving low Tuning voltage and moderate FoM, overshadowed by a little expense of power dissipation. 


Author(s):  
Yuanyu Yu ◽  
Jiujiang Wang ◽  
Xin Liu ◽  
Sio Hang Pun ◽  
Weibao Qiu ◽  
...  

Background:: Ultrasound is widely used in the applications of underwater imaging. Capacitive micromachined ultrasonic transducer (CMUT) is a promising candidate to the traditional piezoelectric ultrasonic transducer. In underwater ultrasound imaging, better resolutions can be achieved with a higher frequency ultrasound. Therefore, a CMUT array for high-frequency ultrasound imaging is proposed in this work. Methods:: Analytical methods are used to calculate the center frequency in water and the pull-in voltage for determining the operating point of CMUT. Finite element method model was developed to finalize the design parameters. The CMUT array was fabricated with a five-mask sacrificial release process. Results:: The CMUT array owned an immersed center frequency of 2.6 MHz with a 6 dB fractional bandwidth of 123 %. The pull-in voltage of the CMUT array was 85 V. An underwater imaging experiment was carried out with the target of three steel wires. Conclusion:: In this study, we have developed CMUT for high-frequency underwater imaging. The experiment showed that the CMUT can detect the steel wires with the diameter of 100 μm and the axial resolution was 0.582 mm, which is close to one wavelength of ultrasound in 2.6 MHz.


1996 ◽  
Vol 165 ◽  
pp. 313-319
Author(s):  
Mark H. Finger ◽  
Robert B. Wilson ◽  
B. Alan Harmon ◽  
William S. Paciesas

A “giant” outburst of A 0535+262, a transient X-ray binary pulsar, was observed in 1994 February and March with the Burst and Transient Source Experiment (BATSE) onboard the Compton Gamma-Ray Observatory. During the outburst power spectra of the hard X-ray flux contained a QPO-like component with a FWHM of approximately 50% of its center frequency. Over the course of the outburst the center frequency rose smoothly from 35 mHz to 70 mHz and then fell to below 40 mHz. We compare this QPO frequency with the neutron star spin-up rate, and discuss the observed correlation in terms of the beat frequency and Keplerian frequency QPO models in conjunction with the Ghosh-Lamb accretion torque model.


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