Phonon black-body radiation limit for heat dissipation in electronics

Abstract

We show photographs of the inside and outside of the 4--16 GHz MMIC LNA chassis including the matching network in Figure 1. When aiming for lowest noise performance, the matching network and performance of the first stage ultimately sets the noise performance. To avoid substrate losses, and consequently degraded noise performance, an external input matching network on a low loss substrate was used. To decrease the magnitude of S 11 (input reflection coefficient) and improve stability, a high inductance source microstrip was used on the first transistor.To achieve flat in--band noise, an impedance matching tradeoff has to be done. The minimum noise temperature of an InP HEMT varies nearly linearly with frequency [1]. Therefore, the best approach to obtain a flat noise temperature within a certain frequency band is by noise matching the first stage at the upper frequency limit, while allowing a certain mismatch at the lower frequencies. The second and third stages were matched for flat gain, stability and output match. The LNA has a common bias network for all three stages. S2: Additional information on noise model and parameter extractionThe noise model and method used for noise parameter extraction is the same as in [2]. The principle of the model is that the noise in the device can be represented by thermal and non--thermal sources. Thermal noise is due to resistive elements in the amplifier, with the magnitude depending on the value of the resistances and the physical temperature. The only non--thermal noise source is hot--electron noise source in the output of the InP high electron mobility transistors (HEMTs). This noise source is typically modeled as an elevated drain temperature T d that is a few orders of magnitude larger than the physical temperature of the HEMT. If the ambient temperature T a of the LNA is known and the noise parameters are measured using the Agilent Noise Figure Analyzer, T d can be obtained by fitting the simulated and

Thickness-dependent Kapitza resistance in multilayered graphene and other two-dimensional crystals

“…This numerical value is comparable to the room-temperature TBR value (∼ 10 −8 m 2 KW −1 ) obtained by Schmidt and co-workers [43] for the interface between highly ordered pyrolytic graphite (HOPG) and Al film with a 5-nm Ti adhesion layer although such a comparison between this TBR value and our projected effective TBR for the graphite/SiO 2 interface cannot be rigorously made as the substrate materials are different. Figure 3 also shows the TBR for N = 1 to 13 and T = 20 to 600 K decreasing with temperature and scaling approximately as R K ∝ T −4 at low temperatures instead of the typical T −3 behavior [1] seen in nonlayered systems [44,45]. The R K ∝ T −4 behavior is also noted in Ref.…”

Dependence of noise temperature on physical temperature for cryogenic low-noise amplifiers

“…Therefore, some of the authors undertook such an investigation for a prototype Planck Ka-band MIC LNA, 6 observing that the noise temperature continued to decrease below 20 K. This paper initially presents the results of a similar study for four MMIC-based radio astronomy LNAs, then discusses these results, showing how they support the findings of a recent study investigating the intrinsic temperature of the HEMT's conduction channel, 7 and finally considers the implications of these findings for future radio astronomy receivers.…”

Plasmonic Heating in Au Nanowires at Low Temperatures: The Role of Thermal Boundary Resistance

“…35 Secondly, the thermal conductivity of most materials has a non-linear and non-monotonic temperature dependence below ~50 K. These effects can be exacerbated in some limits, such as when heater size becomes comparable to the phonon mean free path, 36,37 and when low energy phonon availability is limited. 38 Moreover, as the local metal temperature is increased and induced heating also increases due to the temperature dependence of the dielectric function of gold. These factors combine, leading to a significantly enhanced local temperature and a non-linear dependence of local temperature on the laser intensity or substrate temperature.…”