An accurate and broadband method for the direct extraction of heterojunction bipolar transistor (HBT) small-signal model parameters is presented in this paper. This method differs from previous ones by extracting the equivalent-circuit parameters without using special test structures or global numerical optimization techniques. The main advantage of this method is that a unique and physically meaningful set of intrinsic parameters is extracted from the measured S-parameters for the whole frequency range of operation. The extraction procedure uses a set of closed-form expressions derived without any approximation. An equivalent circuit for the HBT under a forward-bias condition is proposed for extraction of access resistances and parasitic inductances. An experimental validation on a GaInP/GaAs HBT device with a 2/spl times/25 /spl mu/m emitter was carried out, and excellent results were obtained up to 30 GHz. The calculated data-fitting residual error for three different bias points over 1-30 GHz was less then 2%.

Direct parameter-extraction method for HBT small-signal model

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.

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

Direct extraction is the most accurate method for the determination of equivalent-circuits of heterojunction bipolar transistors (HBTs). The method is based on first determining the parasitic elements and then the intrinsic elements analytically. The accuracy and robustness of the whole algorithm therefore is determined by the quality of the extraction of the extrinsic elements. This paper focuses on a new extraction method for the extrinsic capacitances which have proven to be the main source of uncertainty compared to the other extrinsic parameters. Concerning the intrinsic parameters, all the elements are extracted using exact closed-form equations, including exact expressions for the base-collector capacitances, which model the distributed nature of the base. The expressions for the base-collector capacitances are valid for both the hybrid-/spl pi/ and the physics-based T-topology equivalent circuits. Extraction results for InP HBT devices on measured S-parameters up to 100 GHz demonstrate good modeling accuracy.

A peeling algorithm for extraction of the HBT small-signal equivalent circuit

An improved direct parameter extraction method of SiGe heterojunction bipolar transistors (HBTs) for the vertical bipolar intercompany (VBIC)-type hybrid-/spl pi/ model is developed. All the equivalent circuit elements are extracted analytically from S-parameter data only and without any numerical optimization. The proposed technique of the parameter extraction, differing from the previous ones, focuses on correcting the pad de-embedding error for an accurate and invariant extraction of intrinsic base resistance (R/sub bi/), formulating a new parasitic substrate network, and improving the extraction procedure of transconductance (g/sub m/), dynamic base-emitter resistance (r/sub /spl pi//), and base-emitter capacitance (C/sub /spl pi//) using the accurately extracted R/sub bi/. The extracted parameters are frequency-independent and reliable due to elimination of any de-embedding errors. The agreements between the measured and model-calculated data are excellent in the frequency range of 0.2-10.2 GHz over a wide range of bias points. Therefore, we believe that the proposed extraction method is a simple and reliable routine applicable to the optimization of transistor design, process control, and the improvement of VBIC compact model, especially for SiGe HBTs.

Direct parameter extraction of SiGe HBTs for the VBIC bipolar compact model

This work presents an RF model of an accumulation-mode MOS varactor with physical lumped elements derived from the device structure. The channel resistance was modeled by three resistance components to cover both accumulation and depletion regions with single equivalent circuit. With parameter values obtained by direct extraction, this model could accurately describe characteristics of the device without any optimization steps in the frequency range up to 18 GHz, as well as over a wide bias range. Due to the single topology, easy integration of the model into common circuit simulators is possible.

An RF model of the accumulation-mode MOS varactor valid in both accumulation and depletion regions

An original, rigorous and accurate method for the direct extraction of HBT small-signal model parameters is proposed. The main advantage of this method is that a unique and physical-meaningful set of intrinsic parameters is extracted from the measured S-parameters for the whole frequency range of operation. The extraction procedure uses a set of closed form expressions derived without any approximation. In this sense, the extraction method is more accurate and robust in comparison with those employing special test structures or global numerical optimization techniques. Experimental validation on a HBT device with a 2/spl times/25 /spl mu/m emitter was carried out, and excellent results were obtained up to 30 GHz. The calculated data-fitting residual error over 1-30 GHz was less then 2%.

A new analytical and broadband method for determining the HBT small-signal model parameters

A novel and accurate method for the direct extraction of HBT small-signal hybrid-Pi model parameters is proposed. The main feature of this method is that a unique set of intrinsic parameters is calculated for the whole frequency range of operation using a least-squares data fitting algorithm. This algorithm consists of an estimation from measured S-parameters of a set of new analytical equations derived from the intrinsic HBT equivalent-circuit Y-parameters. Experimental validation on an HBT device with a 2x25 mm emitter was carried out, and excellent results were obtained up to 30 GHz.

/pdf/a-novel-direct-extraction-method-for-internal-equivalent-2uz444nl9n.pdf

R. Surridge

Papers

Direct parameter-extraction method for HBT small-signal model

A new analytical and broadband method for determining the HBT small-signal model parameters

A Novel Direct Extraction Method for Internal Equivalent Circuit Parameters of HBT Small-Signal Hybrid-Pi Model