Graphene transistors operating at high frequencies (GHz) have been fabricated and characterized. The measured intrinsic current gain shows an ideal 1/f frequency dependence, indicating FET-like behavior. The cutoff frequency (fT) is proportional to the dc transconductance (gm) of the device, consistent with the relation fT = gm/(2πCG). The peak fT increases with reduced gate length, and a value as high as 26 GHz was measured for a graphene transistor with a gate length of 150 nm. This represents a significant step towards graphene-based electronics for high-frequency applications. Graphene, a two-dimensional material, has high intrinsic carrier mobility, making it promising for high-frequency circuits. However, direct ac measurements of nanotubes were difficult due to high impedance. In contrast, graphene's 2D nature allows for easy scaling of drive current by increasing device channel width. The planar graphene allows for fabrication of integrated circuits using standard semiconductor processes. Recent studies show that graphene devices can exhibit current gain in the microwave range. Despite research efforts, the intrinsic high-frequency transport properties of graphene transistors have not been systematically studied. This study presents the first comprehensive experimental studies on the high-frequency response of top-gated graphene transistors for different gate voltages and gate lengths. The intrinsic current gain of the graphene transistors was found to decrease with increasing frequency and follows the ideal 1/f dependence expected for conventional FETs. This verifies the ac measurement and de-embedding procedures used here for extracting the intrinsic high-frequency properties, and suggests a conventional FET-like behavior for graphene transistors. The cutoff frequency (fT) deduced from S parameter measurements exhibits strong gate voltage dependence and is proportional to the dc transconductance. The peak cut-off frequency is found to be inversely proportional to the square of the gate length, and for a gate length of 150 nm, a peak fT as high as 26 GHz is obtained. The device layout of graphene field-effect transistors with probe pads designed for high-frequency measurements is shown. Graphene was prepared by mechanical exfoliation on a high-resistivity Si substrate. Raman spectroscopy was used to count the number of graphene layers. The device was fabricated with a 12-nm-thick Al2O3 layer as the gate insulator. The dielectric constant of ALD-grown Al2O3 is determined by C-V measurements and found to be about 7.5. Lastly, 10nm/50nm Pd/Au was deposited and patterned to form the top gate. Measurements of dc electrical properties of graphene devices were performed to gain insight into their high-frequency response. The dc electrical characteristics were monitored at each fabrication step to identify issues affecting the final device performance. The field-effect mobility (μeff) can be calculated using the relation Δσ = qΔnμGraphene transistors operating at high frequencies (GHz) have been fabricated and characterized. The measured intrinsic current gain shows an ideal 1/f frequency dependence, indicating FET-like behavior. The cutoff frequency (fT) is proportional to the dc transconductance (gm) of the device, consistent with the relation fT = gm/(2πCG). The peak fT increases with reduced gate length, and a value as high as 26 GHz was measured for a graphene transistor with a gate length of 150 nm. This represents a significant step towards graphene-based electronics for high-frequency applications. Graphene, a two-dimensional material, has high intrinsic carrier mobility, making it promising for high-frequency circuits. However, direct ac measurements of nanotubes were difficult due to high impedance. In contrast, graphene's 2D nature allows for easy scaling of drive current by increasing device channel width. The planar graphene allows for fabrication of integrated circuits using standard semiconductor processes. Recent studies show that graphene devices can exhibit current gain in the microwave range. Despite research efforts, the intrinsic high-frequency transport properties of graphene transistors have not been systematically studied. This study presents the first comprehensive experimental studies on the high-frequency response of top-gated graphene transistors for different gate voltages and gate lengths. The intrinsic current gain of the graphene transistors was found to decrease with increasing frequency and follows the ideal 1/f dependence expected for conventional FETs. This verifies the ac measurement and de-embedding procedures used here for extracting the intrinsic high-frequency properties, and suggests a conventional FET-like behavior for graphene transistors. The cutoff frequency (fT) deduced from S parameter measurements exhibits strong gate voltage dependence and is proportional to the dc transconductance. The peak cut-off frequency is found to be inversely proportional to the square of the gate length, and for a gate length of 150 nm, a peak fT as high as 26 GHz is obtained. The device layout of graphene field-effect transistors with probe pads designed for high-frequency measurements is shown. Graphene was prepared by mechanical exfoliation on a high-resistivity Si substrate. Raman spectroscopy was used to count the number of graphene layers. The device was fabricated with a 12-nm-thick Al2O3 layer as the gate insulator. The dielectric constant of ALD-grown Al2O3 is determined by C-V measurements and found to be about 7.5. Lastly, 10nm/50nm Pd/Au was deposited and patterned to form the top gate. Measurements of dc electrical properties of graphene devices were performed to gain insight into their high-frequency response. The dc electrical characteristics were monitored at each fabrication step to identify issues affecting the final device performance. The field-effect mobility (μeff) can be calculated using the relation Δσ = qΔnμ