Researchers at IBM demonstrated a radio-frequency graphene transistor with the highest cut-off frequency achieved so far for any graphene device – 100 billion cycles/second (100 GigaHertz). 
The wafer-scale, epitaxially grown graphene transistor was created with processing technology compatible to that used in advanced silicon device fabrication.
IBM said it is noteworthy that the frequency performance of the graphene device already exceeds the cut-off frequency of state-of-the-art silicon transistors of the same gate length (~ 40 GigaHertz).
http://www.ibm.com