Low frequency noise conversion in fets under nonlinear operation

Based upon the active line concept, the conversion mechanisms of microscopic low frequency noise (e.g. generation-recombination noise) located in the channel of a Field Effect Transistor (FET) which is driven by a large RF signal is demonstrated. The first consequence is that the based band (low frequency) input gate noise voltage spectral density is dependent on the magnitude of the input RF power applied to the FET. Moreover, the microscopic generation-recombination noise sources located in the channel are responsible of up-converted input gate noise voltage spectral density around the RF frequency

Frequency synthesis from 2 to 30 GHz using a 0.35 µm BiCMOS SiGe technology

In this paper, we present a 10/30GHz MMIC Tripler, an X-band VCO and a frequency divider using a 0.35 µm, 60 GHz-fMAX MMIC BiCMOS SiGe technology. The Tripler exhibits a conversion gain of -5 dB and a low additive phase noise of –143dBc/Hz at a frequency offset of 100kHz is anticipated. In order to drive this Tripler, the design of a MMIC X-band VCO and its measured performance (0.8GHz tuning range, -5 dBm output power and –87dBc/Hz phase noise @ 100kHz of carrier) is also reported. This X band VCO can also drive a frequency divider, developed in the same technology. The assembling of these circuits allows the design of a 2 GHz frequency synthesizer. Measurements have shown a phase noise of -99dBc/ Hz at a frequency offset of 100kHz. Therefore, this paper demonstrates the great capabilities of BiCMOS SiGe MMIC technology about frequency synthesis ranging from 2GHz to 30GHz

Correlation between kink effect and frequency dispersion in pseudomorphic HEMTs

This paper presents DC and AC frequency dispersion effects of the drain-source output impedance in commercially available pseudomorphic HEMTs. Inductive behaviour observed on the imaginary part of the drain-source impedance is attributed to deep traps in the GaAs substrate from DC and AC measurements versus temperature. On the other hand. DC and AC measurements indicate that kink effect signature is related to impact ionisation at the drain edge of the gate followed by trapping-detrapping processes in the substrate

Si vertical JFET at low temperatures ; I-V characteristics and low frequency noise

Measurements of the source to drain current/voltage, Id(Vds), characteristics and low frequency (f < 100kHz) noise spectral density function, SV(f), were carried out at 77K < T < 300K on the vertical JFET (BiCMOS-compatible technology). We found that Id(Vds) characteristics do not significantly depend on T, down to 100K, thus low temperature applications of the device are plausible. At f < 10kHz, SV(f) was found to be dominated by the 1/f component. At low T, SV(f) shows features characteristic for the generation-recombination process, which become stronger at large and negative gate bias polarizations. This suggests that the recombination centers are localized at the interface between the channel and the depletion region near the gate

DC and Low Frequency Noise Characteristics of SiGe n-MODFET’s.

This paper presents an investigation of the low frequency noise properties of SiGe based n MODFET’s through the characterization of both the gate current noise and the drain current noise including their correlation. Measurements versus bias and gate geometry have shown that this noise is generated through mobility fluctuations or carrier diffusion at the gate terminal and that carrier number fluctuations are involved in drain current fluctuations. Microwave residual phase noise measurements have shown that the up-conversion effect mainly occurs on the drain current noise

High bit rate four phase MMIC remodulation demodulator and modulator.

Four phase direct demodulation systems and high bit rate telemetry require four phase modulator. This work describes a four phase modulator development and a demodulator design at X-band frequency in MMIC technology. The modulator and demodulator MMIC design uses lumped elements networks and a 0.5 microns gate length process. Demodulator simulation results are presented. The modulator has been realized, it exhibits low consumption due to the use of cold FETs. Small phase switching times, less than 300 picoseconds, have been measured which confirm high bit rate modulator capability. Carrier rejection of about 28 dB and high clock rejection level are obtained in a QPSK modulation spectrum

Investigation of the burn-in effect in microwave GaInP/GaAs HBTs by means of numerical simulations

The GaInP/GaAs HBTs demonstrate outstadning long-term reliability performance. Nevrtheless they still suffer from a short-term DC current gain instability, known as the Burn-in effect. Even if the effect is usually attributed to Hydrogen contamination passivating the Carbon atoms employed as base dopant, the underlying physical mechanism is still unclear.The present work addresses the Burn-in effect by means of numerical simulations performed with the device simulation software BLAZE by Silvaco. The rsults give support to the hypothesis that the Burn-in effect is a surface related phenomenon. The simulations reveal that a fixed surface charge located near the edge of the emitter mesa should be introduced. The work points out also that simultaneous variations of both this charge and of the surface recombination velocity should be taken into account. This simulation approach could be a useful tool, in order to develop a chemical/physical model of the Burn-in effect

Low-frequency noise properties of GalnP/GaAs/GalnP DHBT's

This paper presents the low frequency noise of double lieterojunction bipolar transistor (DHBTs) based on GalnP/GaAs/GalnP system. From static measurements, we can observe that both surface recombination along the emitter finger and bulk recombination in the extrinsic base region exist in these structure. S parameters measurements show very interesting microwave capabilities with cut-off frequency and maximum oscillation larger than 30 GHz. Concerning the noise properties, the results indicate that both 1/f and generation-recombination are present in DHBT. Both the input noise current and input noise voltage is inversely proportional to the emitter length. The inspection of the correlation between the noise generators reveals that the resistive parts of the device play a role on the overall noise component. Further, we have shown that the noise source at the output is not negligeable. Finally, a comparative noise study between emitter-up and collector-up DHBTs indicate that the noise current source is lower for co[lector-up DHBT than for emitter-up one related to a lower surface recombination rate

Polar mutagenesis of polycistronic bacterial transcriptional units using Cas12a

Background: Functionally related genes in bacteria are often organized and transcribed as polycistronic transcrip‑ tional units. Examples are the fim operon, which codes for biogenesis of type 1 fimbriae in Escherichia coli, and the atp operon, which codes for the FoF1 ATP synthase. We tested the hypothesis that markerless polar mutations could be efficiently engineered using CRISPR/Cas12a in these loci. Results: Cas12a‑mediated engineering of a terminator sequence inside the fimA gene occurred with efficiencies between 10 and 80% and depended on the terminator’s sequence, whilst other types of mutations, such as a 97 bp deletion, occurred with 100% efficiency. Polar mutations using a terminator sequence were also engineered in the atp locus, which induced its transcriptional shutdown and produced identical phenotypes as a deletion of the whole atp locus (ΔatpIBEFHAGDC). Measuring the expression levels in the fim and atp loci showed that many supposedly non‑ polar mutants induced a significant polar effect on downstream genes. Finally, we also showed that transcriptional shutdown or deletion of the atp locus induces elevated levels of intracellular ATP during the exponential growth phase. Conclusions: We conclude that Cas12a‑mediated mutagenesis is an efficient simple system to generate polar mutants in E. coli. Different mutations were induced with varying degrees of efficiency, and we confirmed that all these mutations abolished the functions encoded in the fim and atp loci. We also conclude that it is difficult to predict which mutagenesis strategy will induce a polar effect in genes downstream of the mutation site. Furthermore the strategies described here can be used to manipulate the metabolism of E. coli as showcased by the increase in intra‑ cellular ATP in the markerless ΔatpIBEFHAGDC mutant