A low noise 2-20 GHz feedback MMIC-amplifier

A low noise feedback MMIC-amplifier based on a 180 GHz f(max) PHEMT-technology is described. The gain input and output reflection coefficient, de-power consumption, and noise parameters are investigated theoretically and experimentally as a function of dc-bias and frequency. The noise figure is typically 2.5 dB with an associate gain of 22 dB across the 2-20 GHz frequency range. The circuit area is less than 1 mum(2) and the de-power consumption is lower than 100 mW

The potential for sensitivity enhancement by the thermoelectric effect in carbon-nanotube and graphene Tera-FETs

We report on terahertz (THz) measurements with graphene field-effect transistors with integrated antennas (Tera-FETs) lay special emphasis on thermoelectric contributions to the detected THz photoresponse. Graphene Tera-FETs with integrated broad-band bow-tie antennas were fabricated in a CVD-based growth process and were successfully applied for detection at 600 GHz with optical NEPs down to 515 pW/Hz^1/2. While rectification of THz radiation by (distributed) resistive mixing of charge-density waves induced in the gated transistor channel region is well known, significant additional contributions to the detected signal have experimentally been observed and hot-carrier thermoelectric effects have been identified as a possible origin of these signals. We also observe similar signal contributions in carbonnanotube transistors

Noise performance of a ground gate wideband MMIC amplifier

A broadband ground gate amplifier was designed, fabricated and characterized. Noise parameters of the intrinsic HFETs were measured and simulated by using Pospieszalski noise model. Extracted drain and gate temperatures were used for the characterization of the amplifier noise properties. An input match better than -20 dB in a wide band from 2 to 6 GHz and -10 dB from 1-13 GHz with corresponding 11 dB gain was obtained. NF min of 3 dB was found experimentally at room temperature. A dc power dissipation of less than 20 mW is possible to obtain with this device technology. The total chip area is 2x1.5 mm 2. The active circuit area is less than 1 mm 2. We have simulated amplifiers rf and noise performance with the wider gate HFET at the input

Analysis of the frequency dependent gate capacitance in CNTFETs

Abstract-A time-dependent effective-mass Schrödinger-Poisson solver is used to study the frequency dependence of the gate capacitance of a short Schottky-barrier carbon nanotube field-effect transistor (CNTFET). A delayed (re)charging of the channel causes a (non-quasi-static) drop of the gate capacitance for higher frequencies on a characteristic scale, which can be related to the escape time of the carriers. The impact of Schottky-barriers on the escape time is discussed both analytically and by means of transient simulations. A comparison with experimental data reveals an interesting qualitative similarity. Index Terms-CNTFET, ballistic transport, high-frequency behavior, gate capacitance, double barrier structure, non-quasistatic phenomena, escape tim

Thermal Noise in MOSFETs: A Two- or a Three-Parameter Noise Model?

In this brief, it is clearly demonstrated that a two-parameter noise model is sufficient to accurately extract the MOSFET high-frequency noise performance, as long as channel uniformity is ensured (which corresponds to mainstream CMOS technology). Nevertheless, in the case of asymmetric channel-based MOSFETs, it is shown that a three-parameter noise model is required

Experimental Investigation of RF Noise Performance Improvement in Graded-Channel MOSFETs

In this paper, measured RF noise performance of graded-channel metal-oxide-semiconductor (MOS) transistors (GCMOS-also named laterally asymmetric channel transistors) shows impressive reduction in minimum noise figure (NFmin) as compared to classical MOSFET transistors (with the same gate length L-g = 0.5 mu m). The reason is proven to be because of the higher noise correlation coefficient (C). GCMOS also shows lower sensitivity to extrinsic thermal noise as compared to classical MOSFET. Moreover, it is demonstrated that the use of 0.5-mu m-gate-length GCMOS gives a competitive RF noise performance as compared to 0.25-mu m-gate-length classical nMOS transistors