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A UHF variable gain amplifier for direct-conversion DVB-H receivers
, Article 2009 IEEE Radio Frequency Integrated Circuits Symposium, RFIC 2009, Boston, MA, 7 June 2009 through 9 June 2009 ; 2009 , Pages 551-554 ; 15292517 (ISSN); 9781424433780 (ISBN) ; Sharif Bakhtiar, M ; Medi, A ; IEEE Microwave Theory and Techniques Society; IEEE Electron Devices Society; IEEE Solid-State Circuits Society ; Sharif University of Technology
2009
Abstract
A CMOS fully differential UHF variable gain amplifier for use in a direct-conversion DVB-H receiver is presented employing input devices with variable aspect ratios. High linearity is achieved by reducing the transconductance of the input transistors for lower gain settings. It is shown that this technique has better linearity and noise performance compared to the conventional methods in which the gain reduction is performed at preceding stages. Implemented in TSMC 0.18-μm CMOS process, the inductorless RF VGA covers a voltage gain ranging from 15.5 dB to -6.5 dB with a maximum IIP3 of +24 dBm. The amplifier achieves a 3-dB bandwidth of 1.4 GHz and a minimum noise figure of 5.8 dB while...
Second and third-order distortion suppression technique for noise canceling CMOS LNAs
, Article IEICE Electronics Express ; Volume 6, Issue 13 , 2009 , Pages 959-965 ; 13492543 (ISSN) ; Atarodi, M ; Sharif University of Technology
2009
Abstract
A technique for simultaneous cancellation of noise, second-order distortion and third-order distortion in CMOS LNAs is presented. The proposed LNA topology consists of a matching stage and two common-source amplifier stages, performing single-ended to differential signal conversion with balanced output. The second and third-order nonlinearity of the individual amplifiers as well as the distortion caused by the interaction between the stages are suppressed to achieve high IIP3. A method for intrinsic cancellation of the second-order interaction is employed to reduce the dependence of the IIP3 on the frequency spacing between the interfering signals in the two-tone test. © IEICE 2009
Phase-noise measurement of microwave oscillators using phase-shifterless delay-line discriminator
, Article IEEE Transactions on Microwave Theory and Techniques ; Volume 58, Issue 2 , January , 2010 , Pages 468-477 ; 00189480 (ISSN) ; Banai, A ; Sharif University of Technology
2010
Abstract
In this paper, a modified method based on the frequency discriminator technique for measuring phase noise of microwave oscillators is presented. In the proposed method, the phase shifter is omitted. In contrast, a 90° hybrid with one more channel containing a phase detector, and a low-noise amplifier is added to the measurement setup. It can be said that an in-phase/quadrature phase-noise detection has been developed. With the proposed method, tuning of the variable phase shifter is not needed anymore. Therefore, the measurement is done automatically, and as a result, the measurement time is decreased. Another considerable advantage of this method is that the method is theoretically...