Coherent transistor

Grinberg, A. A.; Luryi, Serge

doi:10.1109/16.223713

Cited by 27 publications

(7 citation statements)

References 14 publications

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“…So far, the attention on obtaining an active transistor operation at frequencies beyond f T has been focused on bipolar transistors. It has been shown that, by proper design of the so‐called resonance phase transistor (RPT), a current‐gain peak can be achieved at any desired frequency, provided the effect is not destroyed by the parasitic elements largely damping away the current‐gain . Analogously to what has been achieved with an appropriate design, a current‐gain peak in bipolar transistors has been reported and ascribed to a resonance originating from the LC oscillation between output capacitance and output parasitic inductance, mainly generated from the interdigitated collector contact metal…”

Section: Introductionmentioning

confidence: 99%

Current‐gain in FETs beyond cut‐off frequency

Crupi

Raffo

Vadalà

et al. 2018

Micro & Optical Tech Letters

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Driven by the fast‐growing demand for high‐frequency applications, electronics engineers are steadily pushing transistor technologies beyond their high‐frequency limits. A key figure of merit to quickly assess the potential of a transistor for high‐frequency applications is given by the cut‐off frequency (fT) that is defined as the frequency at which the short‐circuit current‐gain (h21) drops to unity. However, field‐effect transistors (FETs) can exhibit a current‐gain even at frequencies beyond fT, due to the resonance of the extrinsic reactive contributions leading to a peak in the magnitude of h21. Based on an extensive analysis, this letter aims to demonstrate that, although not all FETs exhibit such a current‐gain peak at frequencies beyond fT, this effect is inherent in any FET devices and its appearance simply depends on the specific amount of the extrinsic reactive contributions, besides to the operating frequency.

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Section: Introductionmentioning

confidence: 99%

Current‐gain in FETs beyond cut‐off frequency

Crupi

Raffo

Vadalà

et al. 2018

Micro & Optical Tech Letters

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“…In addition, circuit designers can benefit from the kinks in h 21 as they enable achieving an increase in the current gain at the resonant frequencies. However, so far, the interest in obtaining active transistor operation at frequencies beyond the cut-off frequency (f T ) has been focused on bipolar transistors (e.g., by proper design of the so-called resonance phase transistor [16][17][18][19][20][21]), recent studies have shown that the achievement of a current gain even at frequencies higher than f T is achievable also in FET transistors, owing to the kinks in h 21 [12,13].…”

Section: Introductionmentioning

confidence: 99%

A New Study on the Temperature and Bias Dependence of the Kink Effects in S22 and h21 for the GaN HEMT Technology

et al. 2018

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The aim of this feature article is to provide a deep insight into the origin of the kink effects affecting the output reflection coefficient (S22) and the short-circuit current-gain (h21) of solid-state electronic devices. To gain a clear and comprehensive understanding of how these anomalous phenomena impact device performance, the kink effects in S22 and h21 are thoroughly analyzed over a broad range of bias and temperature conditions. The analysis is accomplished using high-frequency scattering (S-) parameters measured on a gallium-nitride (GaN) high electron-mobility transistor (HEMT). The experiments show that the kink effects might become more or less severe depending on the bias and temperature conditions. By using a GaN HEMT equivalent-circuit model, the experimental results are analyzed and interpreted in terms of the circuit elements to investigate the origin of the kink effects and their dependence on the operating condition. This empirical analysis provides valuable information, simply achievable by conventional instrumentation, that can be used not only by GaN foundries to optimize the technology processes and, as a consequence, device performance, but also by designers that need to face out with the pronounced kink effects of this amazing technology.

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“…[7] have derived the following expression for the base transport factor er a3 = cosh(A) + (1 + 2 ico rB,drift / r)2 sinh(Q) (3) where i= r2 + 2ictrB,diff and r is the ratio of the diffusion time T,Bdiff = WB /2Db to the drift time tB,drift = WB / v . Assuming for simplicity COTE << I the output resistance becomes [9] R OS(-P) -COS((P +e)||R Inserting eq. (2) to (5) into eq.…”

Section: Cbc-rbr22mentioning

confidence: 98%

“…Following Grinberg and Luryi [9], in the intrinsic transistor (REX= RBX= R>X= 0), the unilateral gain including transit time effects is given by aBac 2…”

Section: Introductionmentioning

confidence: 99%

Transistor Action by Transit Time Phase Shift - a Study for SiGe Based Devices

Weller

Jorke

Strohm

et al. 1998

28th European Microwave Conference, 1998

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In the present paper we report on a study on extendedfrequency operation in Si/SiGe heterojunction bipolar transistor structures. Calculations based on the results from a previous survey show the conditionsfor which an active behaviour in excess offmax can be obtained High frequency transistors with various shaped base potentials are produced and the unilateral gain is deduced from S-parameter measurements. A first indication of an active behaviour at frequencies above fmax is observed. This preliminary study serves as a guideline for designing structures which enables extended frequency operation.

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Coherent transistor

Cited by 27 publications

References 14 publications

Current‐gain in FETs beyond cut‐off frequency

Current‐gain in FETs beyond cut‐off frequency

A New Study on the Temperature and Bias Dependence of the Kink Effects in S22 and h21 for the GaN HEMT Technology

Transistor Action by Transit Time Phase Shift - a Study for SiGe Based Devices

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