Some general relationships for flicker noise in MOSFETs

A general relationship is derived for the spectral intensity S_tg(f) of flicker noise in MOSFETs caused by fluctuations δN in the number of carriers in a section Δx of the channel. Various previous theories follow as special cases. If the device is uniform, the noise intensity at arbitrary drain bias V_d can be expressed in terms of the noise intensity for $\text{V}{}_{\mathrm{d}}\text{? 0}$.     

New flowgraph mode and calibration procedure for S-parameter measurements of devices mounted in microstrip fixture

The letter reports microstrip devices under test (DUT), and gives a new flowgraph mode and calibration procedure for determining error terms. Explicit formulas are given for error terms and S-parameters of the DUT.     

A general noise de-embedding procedure for packaged two-port linearactive devices

A method based on the noise correlation technique and its applications is described. The package, which need not be reciprocal, may consist of an arbitrary interconnection of linear passive elements at thermal equilibrium. Only the terminal admittance properties of the package need be known. However, in certain special cases which lead to singular submatrices of the admittance matrix, the method is inapplicable. This situation can occur when elements such as isolators are part of the package. The necessary theoretical foundation and experimental techniques to enable workers not familiar with the field to assemble the software and laboratory setup for two-port noise de-embedding is provided. The automated noise measurement system used for data acquisition and the mathematical basis for it are described in some detail. The validity of the de-embedding approach is established with extensive experimental data obtained on three MESFETs and a pseudomorphic HEMT     

Modulated S-parameter measurements for isothermal microwave devicecharacterization

The validity of extracted microwave device models is critically dependent on the completeness, accuracy, and appropriateness of the starting device characterization data. In this letter we will present a novel technique for determining the S-parameters of a device under isothermal (i.e., no heating) operation. Additionally, this technique can be applied to determining the CW S-parameters under more extreme (e.g., forward bias/breakdown) operation. By pulse-biasing the device from the “OFF” to the “ON” state, while performing standard S-parameter measurements, resultant data is found to be characteristic of the weighted (by duty factor) scalar sum of the devices “ON”-state and “OFF”-state S-parameter(s). We will show how these measurements can then be used to interpret the devices isothermal CW S-parameters     

A low-frequency noise model for advanced gate-stack MOSFETs

A new unified noise model is presented that accurately predicts the low-frequency noise spectrum exhibited by MOSFETs with high dielectric constant (high-k), multi-stack gate dielectrics. The proposed multi-stack unified noise (MSUN) model is based on number and correlated mobility fluctuations theory developed for native oxide MOSFETs, and offers scalability with respect to the high-k/interfacial layer thicknesses. In addition, it incorporates the various electronic properties of high-k/interfacial layer materials such as energy barrier heights between different gate layers, and dielectric trap density with respect to band energy and position in the dielectric. For verification of the new model, the low-frequency noise, DC and conventional split C-V measurements were performed in the 78-350 K temperature range on TaSiN/HfO₂ n-channel MOSFETs. The interfacial layer in these devices was either thermal SiO₂ by Stress Relieved Pre-Oxide (SRPO) pretreatment or chemical SiO₂ resulting from standard RCA (Radio Corporation of America) clean process. Using the experimental noise data, the channel carrier number fluctuations mechanism was at first established to be the underlying mechanism responsible for the noise observed at all temperatures considered. Secondly, the normalized noise exhibited a weak dependence on temperature implying that the soft optical phonons, although known to result in mobility degradation, have no effect on the noise characteristics in these high-k gate stack MOSFETs. Finally, the new model was shown to be in excellent agreement with the measured noise in 1-100 Hz frequency range at temperatures of 78-350 K for both gate stacks.     

A simple four-port parasitic deembedding methodology for high-frequency scattering parameter and noise characterization of SiGe HBTs

A new four-port scattering parameter (S-parameter) and broad-band noise deembedding methodology is presented. This deembedding technique considers distributed on-wafer parasitics in the millimeter-wave band (f>30GHz). The procedure is based on simple analytical calculations and requires no equivalent circuit modeling or electromagnetic simulations. Detailed four-port system analysis and deembedding expressions are derived. Comparisons between this new method and the industry-standard "open-short" method were made using measured and simulated data on state-of-the-art SiGe HBTs with a maximum cutoff frequency of approximately 180 GHz. The comparison demonstrates that better accuracy is achieved using this new four-port method. Based on a combination of measurements and HP-ADS simulations, we also show that this new technique can be used to accurately extract the S-parameters and broad-band noise characteristics to frequencies above 100 GHz.     

100 GHz active electronic probe for on-wafer S-parameter measurements

Reports the development of an active electronic probe for 100 GHz on-wafer S-parameter measurements. Integrated on the substrate of this wafer probe were a quintupler for 100 GHz stimulus signal generation, two directional couplers for incident and reflected signals sampling, and two newly developed harmonic mixers to down-convert these 100 GHz signals to 20 MHz. The authors also demonstrate all-electronic on-wafer 75-100 GHz two-port S-parameter measurements using these probes.<>     

Low-frequency noise measurements on submicrometre n-channel and p-channel MOSFETs at various operating regions

Silicon founders give in their MOS transistor card models some low-frequency noise parameters for SPICE-based circuit simulators corresponding to pure 1/f ^a or flicker noise, with a very close to unity. MOS transistors used in analogue circuit applications are usually devices with large channel length and width. In low-noise applications, methods such as correlated double sampling are used to suppress the low frequency noise generated by them. Nevertheless, the transistors presently are submicrometre devices exhibiting very different low-frequency noise behaviour. In this paper, experimental low-frequency noise results obtained at room temperature on NMOS and PMOS transistors fabricated using a 0.7 μm process are presented. Both large and small devices on the same process are considered. All regions of operation of transistors are considered. We show that the low-frequency noise behaviour of small area MOSFETs is very different from that of large area devices and that the spectrum is the summation of Lorentzian spectra generated by the switching of individual active traps.     

Analytical modeling of MOSFETs channel noise and noise parameters

Simple analytical expressions for MOSFETs noise parameters are developed and experimentally verified. The expressions are based on analytical modeling of MOSFETs channel noise, are explicit functions of MOSFETs geometry and biasing conditions, and hence are useful for circuit design purposes. Good agreement between calculated and measured data is demonstrated. Moreover, it is shown that including induced gate noise in the modeling of MOSFETs noise parameters causes /spl sim/5% improvement in the accuracy of the simple expressions presented here, but at the expense of complicating the expressions.     

S-parameter measurements and microwave applications ofsuperconducting flux flow transistors

Microwave two-port S-parameter measurements and modeling of superconducting flux flow transistors are presented. The transistors, based on the magnetic control of flux flow in any array of high temperature superconducting weak links, exhibit significant available power gain at microwave frequencies (over 20 dB at 7-10 GHz in some devices). The input impedance is largely inductive while the output impedance is both resistive and inductive. It is shown that the characteristics of these devices are useful in numerous applications including matched amplifiers, phase shifters and active impedance convertors     

Excess high frequency noise and flicker noise in MOSFETs

The noise parameter α=R_ng_m, where R_n is the noise resistance and g_m the transconductance, was measured for n- and p-channel MOSFETs as a function of frequency with the temperature T as a parameter. At lower frequencies α varies as 1/f, as expected for flicker noise, whereas at higher frequencies α attains a limiting value α_∞ that is larger than expected for thermal noise. Arguments are presented whether this high-frequency noise can be hot electron noise. The flicker noise resistance R_mf has a much stronger temperature dependence for n-channel than for p-channel devices; this is related to the energy dependence of the surface state distribution in the forbidden gap.     

A general approach for the S-parameter design of oscillators with 1and 2-port active devices

A circular function that serves as a basis for deciding if a circuit will continuously oscillate is introduced. The circular function is derived from the signal flow graph of the circuit including the external load. Any node in the flow graph can be split into two nodes, one of which contains incoming branches and the other of which contains outgoing branches. The circular function is then the transfer function between the two nodes, and it can be measured or simulated by looking at the reflection coefficient of a circulator inserted at the node that was originally split. Oscillations occur when the circular function is unity. The stability of these oscillations is determined by considering the behavior of the circular function as the circuit saturates. The circular function can be applied to one-port oscillators that use negative resistance devices and to feedback oscillators containing transistors, and it reduces to previously published results for specific circuit topologies. To verify the practicality of this approach two 30 GHz HEMT oscillators were designed and tested     

A new type of flicker noise in microwave MOSFETs

Signetics SD 200 microwave n-channel MOSFETs show a type of flicker noise in the 4–30 MHz frequency range for which the product of the noise resistance R_n and the transconductance g_m is practically independent of operating conditions. Since this conflicts drastically with Klaassen's theory of flicker noise in MOSFETs, which is backed up by considerable experimental evidence, it is concluded that this represents a new type of flicker noise.     

Consideration of low-frequency noise in MOSFETs for analogperformance

Low-frequency noise characteristics of MOSFETs have been studied in terms of their dependence on metal interconnect perimeter length, device W/L ratio, and gate-biasing voltage. In contrast to the theoretical model, a noise intensity increasing with lowering gate biasing was observed, which suggests that a compromise between noise performance and gain/offset voltage needs to be carefully examined in analog circuit design. Low-frequency noise was also found to be dependent on W/L ratio in devices with the same gate area, which should be considered in future device scaling     

A self-consistent extraction procedure for source/drain resistance in MOSFETs

A new method to determine source/drain series resistance has been developed for MOSFETs operated in linear region. The source/drain resistance (R_SD) is gate-bias dependent. Channel length reduction (ΔL) is extracted at low gate bias and chosen to be constant. All parameters extracted in this method are assumed to be independent of mask channel length for model simplicity. The method has been applied to devices with mask channel lengths of 0.23, 0.2, and 0.185 μm. The extracted parameters are consistent with the assumptions and have been validated by measured I-V characteristics.     

Random telegraph noise of deep-submicrometer MOSFETs

The random telegraph noise exhibited by deep-submicrometer MOSFETs with very small channel area (⩽1 μm²) at room temperature is studied. Analysis of the amplitude of the current fluctuations reveals that the trapped charges generate noise through modulation of the carrier mobility in addition to the carrier number. Parameters needed for modeling the carrier mobility fluctuation effect on the flicker noise in conventional MOSFETs are extracted directly from the random telegraph noise data     

S-parameter broad-band measurements on-microstrip and fastextraction of the substrate intrinsic properties

A broad-band technique for determining the electromagnetic properties of isotropic film-shaped materials, which uses a microstrip line, is presented. Complex permittivity and permeability are computed from analytical equations and S-parameter measurements of microstrip cells propagating the dominant mode. Measured ϵ_r and μ_r data for several materials are presented between 0.05 GHz and 40 GHz. This technique shows a good agreement between measured and predicted data     

S-parameter broadband measurements on-coplanar and fast extractionof the substrate intrinsic properties

A broadband technique for determining the electromagnetic properties of isotropic thin-film materials, which uses a coplanar line, is presented. Complex permittivity and permeability are computed from S-parameter measurements of a coplanar cell propagating the dominant mode. Measured ε_τ and μ_τ data for several materials are presented between 0.05 GHz and 40 GHz. This technique shows a good agreement between measured and predicted data