The effect of emitter-current density on popcorn noise in transistors

It was found experimentally that the pulsewidth of popcorn noise has a dependence on the emitter current density. Experimental results show that, when a transistor having popcorn noise is operated at the emitter current density less than about 1.56 × 10^-1A/cm², the popcorn-noise characteristic is scarcely in the frequency range higher than 15 Hz, well below the audible frequency limit.     

Discussion of various views on popcorn noise

Conflicting ideas regarding popcorn (burst) noise are compared. It is shown that it is premature to use a single model or claim for a unique representation and explanation.     

Reduction of popcorn noise in integrated circuits

Popcorn (burst) noise continues to deteriorate the operation of linear IC devices. Reduction of popcorn noise by a few simple modifications in the manufacturing process is reported in this paper. Annealing in an HC1 atmosphere to getter metal impurities and slow pulling after emitter deposition to diminish stress-induced junction defects appear to reduce the popcorn noise significantly.     

Temporal frequency dependence of modal noise in fibres

For a particular source and fibre, frequency correlation effects determine speckle contrast. For a specified degree of spatial filtration, speckle contrast in turn determines modal noise statistics. The measurement and analysis is reported of the correlation of two multimode fibre speckle patterns as a function of their source frequency difference.     

Comments on "Measurements and interpretation of low frequency noise in FET's"

It is shown that, according to the theories of 1/f noise in MOST's by Klaassen [1] and Berz [2], the mean-square equivalent noise voltage at the gate Vgn²is proportional to the effective surface state density Nss, and not to NssVg(Vg= gate voltage), as was stated for these theories by Das and Moore. Therefore, contrary to what was concluded by Das and Moore, there is no conflict between these theories and the experimental results by Das and Moore which show that Vgn²varies with gate voltage as Nss.     

Probability density function for the phase and frequency noise in a semiconductor laser

A physical definition for the phase and frequency noise of a semiconductor laser is given, which can be applied in determining the performance of coherent optical communication systems. The definition allows a filtered Poisson model to be developed for the probability density function (pdf) of the laser output phase or frequency noise, based on evaluating the cumulants of the noise processes. A condition is derived to quantify under what laser and system conditions a Gaussian pdf is a good approximation. It is shown that the phase and frequency noise can increase significantly for bit rates approaching the relaxation oscillation frequency of the laser diode.     

高斯型功率谱噪声调频信号的性能分析

具有高斯型功率谱的噪声调频信号通过带限信号处理系统时,存在信号能量与距离分辨力的损失,针对此问题,推导了在带限情况下噪声调频信号的能量表达式与基于自相关函数-3 dB主瓣宽度的距离分辨力表达式.结果表明:可以近似认为噪声调频信号所需的最低系统带宽为其9 dB带宽,约等于4倍有效调制带宽,此时信号能量损失不超过5％,自相关函数-3 dB主瓣展宽不超过12％.仿真实验验证了理论结果的正确性.     

Comments on zero-point energy,quantum noise and spontaneous-emission noise

The differences and the connections between zero point fluctuations, quantum noise and spontaneous emission noise and their relevance on measurements of electromagnetic fields are discussed.     

The effects of distributed base potential on emitter-current injection density and effective base resistance for stripe transistor geometries

Simple analytic expressions are derived for the variation of base current, emitter current and emitter-base voltage along the emitter junction of a transistor structure due to the flow of dc base current parallel to the emitter junction. The effective width of the emitter region is discussed, and it is shown that as the emitter width is increased, the effective emitter width approaches a constant value. The change in base resistance with emitter current is also calculated. The use of base contacts on each side of an emitter region is discussed and the analysis is shown to be applicable to this problem for equal or unequal division of base current between the two contacts. The results are applied to a planar transistor structure.     

Temperature dependence study of two-dimensional electron gas effecton the noise performance of high frequency field effect transistors

We present experimental evidence that the noise figure (NF) and associated gain equal to those achieved with GaAs pseudomorphic high electron mobility transistors (GaAs p-HEMT's) can also be accomplished by ion implanted GaAs metal-semiconductor field-effect transistors (GaAs MESFET's). These measured noise figure results as a function of low temperature for GaAs MESFET's and p-HEMT's clearly suggest that the transport properties of the two-dimensional electron gas in HEMT's and p-HEMT's do not make a significant contribution to the noise reduction at high frequency operation of these devices     

Comments on hot carrier noise in field-effect transistors

Taking into account more rigorously such high field effects as velocity saturation and an increasing free carrier temperature, a new derivation is presented for the output noise of the field-effect transistor. It is shown that for devices with a short channel and a high saturation voltage the equivalent noise resistance can increase considerably above the low field value.     

Comments on circuit models for MOSFET thermal noise

It is shown that some current and proposed SPICE models for MOS thermal noise are inconsistent, either when moving from one operating region to another or when changing model levels. A different model is shown to be consistent with theory in all regions and with all SPICE model levels. The reasons for the inconsistency are explored     

Extension of the frequency range of the noise spectral density in silicon p-n structures irradiated with gamma-ray quanta

The possibility of intentionally shifting the high-frequency edge of plateau in the noise spectral density of silicon p-n structures to higher frequencies under irradiation with gamma-ray quanta was studied. The largest increase in the extent of the operating-frequency range was observed to amount to 2–2.5 times. As the irradiation dose increased further, the plateau width did not increase, and its boundary became less abrupt. Correlation between the variation in the effective lifetime of minority charge carriers and the width of low-frequency plateau in the noise spectral density was found. A qualitative model describing the variation in the noise spectral density with increasing irradiation dose for silicon p-n structures with microplasma channels governed by the p-n junction dimensions is suggested.     

On the signal dependence of avalanche noise generation

The influence of ionization in the drift space of an IMPATT diode on the noise generation in the avalanche process is studied. It is found that carrier generation by ionization in the drift space increases the current minima between the current pulses as generated in the avalanche region. The build-up of new avalanche current pulses therefore starts from a higher current level and consequently the behavior is less noisy. The effect of this decrease in noise on the IMPATT-diode oscillator FM noise is estimated.     

Comments on `New monolithic switched-capacitor differentiators withgood noise rejection'

For the original article see ibid., vol.24, no.1, p.177-80 (1989). The commenter notes that the basic inverting SC differentiator described by C.-Y. Wu et al. was proposed by B.J. Hosticka and G. Moschytz (1979), and the behavior of the earlier circuit is discussed. The commenter also points out that the operational amplifiers in the SC filter of Wu et al. must slew in each φ₁ phase from the signal value to ground, thus limiting the maximum usable clock frequency     

Research on optimizing the noise figure of low noise amplifier method via bias and frequency

In this paper,we present the design of an integrated low noise amplifier(LNA)for wireless local area network(WLAN)applications in the 5.15-5.825 GHz range using a SiGe BiCMOS technology.A novel method that can determine both the optimum bias point and the frequency point for achieving the minimum noise figure is put forward.The method can be used to determine the optimum impedance over a relevant wider operating frequency range.The results show that this kind of optimizing method is more suitable for the WLAN circuits design.The LNA gain is optimized and the noise figure(NF)is reduced.This method can also achieve the noise match and power match simultaneously.This proposal is applied on designing a LNA for IEEE 802.11a WLAN.The LNA exhibits a power gain large than 16 dB from 5.15 to 5.825 GHz range.The noise figure is lower than 2 dB.The OIP3 is 8 dBm.Also the LNA is matched to 50 Ω input impedance with 6 mA DC current for differential design.     

Implication of transistor frequency dependence on intermodulation distortion

An analysis is presented for third-order and second-order nonlinear distortion as a function of frequency for a transistor biased in the common-emitter configuration. It is found that, at high frequency, it is the curvature in the loaded cutoff frequency versus collector current curve that determines the degree of intermodulation distortion. Design proposals for obtaining linear cutoff frequency curves (i.e., small third-order distortion) will be discussed.     

Experimental observation of the dependence of avalanche noise on carrier ionization coefficients

McIntyre has predicted that avalanche noise is strongly dependent on the ionization coefficients of the carriers initiating the avalanche process. Carriers with lower ionization coefficient produce higher avalanche noise. The experimental results described here confirm the theoretical prediction that in silicon, where the ionization coefficient of holes is an order of magnitude smaller than the ionization coefficient of electrons, the avalanche noise generated by the hole current can be as much as two orders of magnitude larger than the avalanche noise generated by electron current.