Seonghearn Lee

A novel approach to extracting small-signal model parameters of silicon MOSFET's

We present a simple and accurate method to extract a small-signal equivalent circuit model of Si MOSFETs, based on the novel approach to determining parasitic inductances and resistances by fitting the frequency response of new analytic expressions with Z-parameters. This method is proposed to overcome the serious problem that conventional cold-FET methods cannot be applied for MOSFETs, and is also superior to the traditional optimization of the entire model parameters to fit the measured S-parameters. In particular, this technique is simple and reliable because no additional measurements are needed. The excellent correspondence is achieved between modeled and measured S-parameters from 0.5 to 39.5 GHz.

The detailed analysis of high Q CMOS-compatible microwave spiral inductors in silicon technology

We present the extensive experimental results and their detailed analysis showing the important effects of layout parameters on the frequency responses of quality factor (Q) of rectangular spiral inductors, which are fabricated on a silicon substrate by using conventional silicon CMOS technology, in order to determine the desirable values of layout parameters for designing the high Q inductors used in RF ICs applications. Analysis of the inductors on Si substrates with three kinds of resistivities has been performed by tailoring the geometric layout and varying the metal thickness. Using these results, the substrate effects on RF performance of inductors are also investigated by observing the frequency responses of Q with varying the substrate resistivity in detail.

CMOS layout and bias optimization for RF IC design applications

High frequency and low noise performance of 0.8 /spl mu/m polysilicon gate CMOS device has been analyzed intensively with the various multi-finger polysilicon gate layout and bias to find the optimal condition. From the analysis, the optimal width of unit gate finger and bias condition have been found to maximize f/sub max/ and minimize F/sub min/. At the conditions, F/sub min/, gain and noise resistance characteristics of large width transistors are also analyzed.

Parameter extraction technique for HBT equivalent circuit using cutoff mode measurement

A parameter extraction method based on the S-parameter measurements of the heterojunction bipolar transistors (HBTs) biased to cutoff is proposed. This method is applied to confirm the results for the RF probe pad and interconnection pattern parasitics obtained from the special test structures, and to determine some of the device capacitances of the HBT. The remaining device parameters are extracted by the S-parameter measurements of the devices biased to the active mode. The extraction technique gives good agreement between the equivalent circuit and the measured S-parameters of the HBT including probe pads and interconnections. >

New circuit model for RF probe pads and interconnections for the extraction of HBT equivalent circuits

A new circuit model for RF probe pads and interconnections is proposed, and this model and previous models are compared with measured S parameters of probe pad and interconnection test structures. A modified parameter and interconnnection model was used to determine an HBT equivalent circuit. Excellent agreement is obtained between the extracted equivalent circuit and measured HBT S parameters, while providing physically acceptable parameter values.<<ETX>>

Optimization of high Q CMOS-compatible microwave inductors using silicon CMOS technology

We present the extensive experimental results showing the important dependences of layout parameters on RF performance of rectangular spiral inductors, in order to determine the optimized layout parameters for designing the high Q inductors used in RF ICs at 2 GHz. The detailed comparative analysis is also carried out to investigate substrate effects by varying the substrate resistivity.

Plasma deposited silicon nitride encapsulant for rapid thermal annealing of Si-implanted GaAs

Silicon nitride films were deposited by the plasma‐enhanced chemical vapor deposition (PECVD) method in a silane and nitrogen atmosphere as encapsulants for rapid thermal annealing of Si‐implanted GaAs. The deposition rate and refractive index of PECVD silicon nitride films were measured with varying the radio‐frequency (rf) power, chamber pressure, N2/SiH4 ratio, and substrate temperature. A wide range of deposition parameters was used, and this range of rf power dependence has not been previously reported.

Transit time effect in high-frequency characteristics of HBTs

Multiple negative resistance bands are predicted at frequencies beyond f/sub max/ in the conventional mesa-type emitter-up AlGaAs-GaAs HBTs (heterojunction bipolar transistors) with careful design and reduced parasitics. Thus, HBT power gain may be obtained in these frequency bands with the negative resistance even above f/sub max/. To obtain the usable transit time effect with large negative resistance, the increase of collector transit time is preferable to increasing base transit time. Therefore, for transit time HBTs, the base should be designed to be as thin as possible, and the collector should be thick enough to obtain the large transit time in the frequency range of interest, while keeping parasitics small.<<ETX>>

New RF-probe pad and interconnection model and parameter extraction technique for HBT equivalent circuit

A novel equivalent circuit model of RF probe pads and interconnections for S-parameter measurements, together with a novel parameter extraction method based on the S-parameter measurements of HBTs (heterojunction bipolar transistors) in the cutoff mode, is presented. This circuit and the extraction technique give very accurate and self-consistent results. The extracted equivalent circuit of the device and probe-pattern parasitics using the technique show excellent agreement with the measured S-parameters.<<ETX>>

Parameter extraction technique for accurate measurement of minority electron mobility in N-p-n AlGaAs/GaAs HBTs

Determination of the experimental value of minority electron mobility mu /sub n//sup p/ in p-type GaAs doped to 3.0*10/sup 19/ cm/sup -3/ at 300 K is discussed. The value was obtained by extracting the base transit time using the plot of total emitter-collector transit time vs. 1/I/sub e/ and parameter extraction of extrinsic parasitics. The experimental value of 2240 cm/sup 2//V-s is in good agreement with theoretical predictions which show the increase of mu /sub n//sup p/ with increasing doping concentrations at doping range larger than 10/sup 19/ cm/sup -3/. Using this parameter extraction technique, the reduction of the base transit time was observed in the Al/sub x/Ga/sub 1-x/As/GaAs composition graded base HBT.<<ETX>>