Noise Canceling Balun-LNA with Enhanced IIP2 and IIP3 for Digital TV Applications

Saeed SAEEDI  Mojtaba ATARODI  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E95-C   No.1   pp.146-154
Publication Date: 2012/01/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E95.C.146
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Integrated Electronics
Keyword: 
active balun,  distortion cancellation,  low noise amplifier,  noise cancellation,  output balancing,  

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Summary: 
An inductorless low noise amplifier (LNA) with active balun for digital TV (DTV) applications is presented. The LNA exploits a noise cancellation technique which allows for simultaneous wide-band impedance matching and low noise design. The matching and amplifier stages in the LNA topology perform 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 IIP2 and 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 of DTV tuners. Fabricated in a 0.18 µm CMOS technology, the LNA core size is 0.21 mm2. Measurements show that the LNA IIP3 and IIP2 are +12 dBm and +21 dBm, respectively. The IIP3 variation is less than 5 dB in the 10 MHz to 200 MHz frequency spacing range. A voltage gain of 14.5 dB and a noise figure below 4 dB are achieved in a frequency range from 100 MHz to 1 GHz. The LNA consumes 11 mA from a 1.8 V supply voltage.