## Results

**Report 2013**

Graphene based multiplier is fabricated using the technology methods fixed in 2012 without notable changes. The CPW line which covered graphene from the multiplier presented in 2012 has two coupled lines in the center of the signal with a length of 36 mm and the separation between them 1 mm. The design used for the multiplier is chosen because using graphene is a nonlinear element the two coupled lines of the CPW are used to excite graphene with a signal with f0 frequency and collect the response nf0. For this point of view the multiplication circuits is adapted to the graphene proprieties and is different of the semiconductor multiplier.

*Fig.1 Frequency multiplier based on graphene using coupled lines on central signal*

*Fig. 2. Multiplication of the input frequency f0 =5 GHz and input power 0 dBm.*

The experimental results demonstrate that for the high frequency more than 20 GHz the harmonic amplitude increase because the millimeter wave absorption decrease with the frequency. The results presented proved that the measurements are in concordance with the theoretical approach. There are also multiplication for an input frequency of 12 GHz.

In conclusion for this year is reported design and realization of a multiplier using nonlinear effect done by the graphene proprieties. Instead of semiconductor multipliers the amplitude of harmonic increase with the frequency because the graphene losses decrease in the same time with the increase of frequency being the only one material which has this proprieties.

1. Daniela Dragoman and Mircea Dragoman, *Geometrically induced rectification in* *two-dimensional ballistic nanodevices*, J. Phys. D: Appl. Phys. **46 **(2013) 055306 (6pp)

2. Mircea Dragoman, Alina Cismaru, Adrian Dinescu, Daniela Dragoman, G. Stavrinidis, and . G. Konstantinidis*, Enhancement of higher harmonics in graphene-based coupled coplanar line microwave multipliers*, Journal of Applied Physics **114**, 154304 (2013);

3. Martino Aldrigo, Mircea Dragoman, Alessandra Constanzo, and Daniela Dragoman, *Graphene as a high impedance surface for ultra-wideband electromagnetic* *waves*, Journal of Applied Physics 114, 184308 (2013);

4. M.Dragoman, *Nanoelectronics on a single atom sheet*, Romanian Reports in Physics, Vol. 65, No. 3, P. 792–804, 2013.