Jie Cui

The total-dose-effects of gamma and proton irradiations on high-voltage silicon–germanium heterojunction bipolar transistors

The total-dose-effects of gamma and proton irradiations on high-voltage silicon–germanium heterojunction bipolar transistors with the collector electrode elicited from the backside of the substrate are investigated. Pre- and post-radiation DC characteristics of the transistors are used to quantify the dose tolerance to the two different irradiation sources. Measurement results indicate that the devices exhibit a total dose tolerance up to Mrad level. The device response is indeed radiation source dependent and the proton irradiation can produce a more significant damage than the gamma irradiation, causing more pronounced performance degradation. The experimental results from both irradiations are compared and discussed in detail, and furthermore the underlying physical mechanisms are analyzed and investigated. The considerably different degradation behaviors are attributed to the extra displacement damage besides ionizing damage induced by the proton irradiation.

An Improved Small-Signal Model for SiGe HBT Under OFF-State, Derived From Distributed Network and Corresponding Model Parameter Extraction

An improved high-frequency small-signal model for SiGe HBTs under the off-state is presented in this paper. The proposed model takes into account the distribution characteristics of the intrinsic transistor, link base region under spacer, and extrinsic base-collector junction. The equivalent circuit for each region is separately derived using the transmission line equation with reasonable approximations. Being different from previous models, the intrinsic base resistance in the proposed model is pushed inside the internal base node and added to the components of collector and emitter resistance. To extract all the parameters for the proposed model, a novel extraction technique based on rational function fitting over the whole range of frequencies is developed. After the rational function fitting to related admittance parameters, a number of coefficients are accurately obtained and then all the model parameters are directly extracted without any special test structure or numerical optimization. The proposed model and extraction technique are validated with a series of sized SiGe HBTs from 100 MHz to 20.89 GHz at a wide range of bias points. An excellent agreement is obtained between the measured and simulated S-parameters.

Novel extraction of emitter resistance of SiGe HBTs from forward-Gummel measurements

A simple dc method for determining the emitter series resistances of bipolar transistors from the measured forward-Gummel characteristics is proposed. The method is successfully applied to a set of SiGe HBTs with different sizes, which have been fabricated and measured over a large temperature range. As a result, the temperature scaling and geometric scaling characteristics of the extracted emitter series resistances are analyzed and discussed.

Analysis and design of a 400MHz-6GHz quadrature demodulator with high linearity

In the paper, a high linearity quadrature demodulator based on SiGe BiCMOS process is designed and implemented for 400MHz to 6GHz wireless communication application. The 3rd intermodulation cancellation technique is applied to improve linearity. A negative feedback structure is applied to Gilbert mixer to lower its input impedance and expand its bandwidth. Quadrature local oscillator signal generator is integrated, with excellent quadrature performance in the whole band. Measurement results show excellent performance in the frequency band of 400MHz to 6GHz.

An accurate parameter extraction method for RF LDMOSFET small-signal model

A new direct parameter extraction method of small-signal equivalent circuit for radio frequency laterally-diffused Metal Oxide Semiconductor Field Effect Transistor (RF LDMOSFET) with Faraday shield biased in cut-off operation is presented in this paper. A series of analytical equations are derived for non-linear rational function fitting as well as linear regression to measured device frequency response characteristics. The method is successfully applied to a set of fabricated RF LDMOSFETs with different geometry scales. As a result, all of the cut-off small-signal equivalent circuit elements are determined. Validation of the extraction method is verified by good agreement between the simulation results and the corresponding measurement data. In addition, reasonable physical meaningfulness of the method is further demonstrated by characterizing the device geometrical dependences of the extracted gate-drain capacitance (Cgd) and drain-source capacitance (Cds).

Novel method to determine base resistance in SiGe HBT HICUM based on rational function fitting

An accurate and efficient base resistance (RB) extraction methodology for SiGe HBT HICUM model is developed in this paper. Differing from previous methods, the proposed technique is based on the rational function fitting. Two formulas are used to determine the lower and upper limits of RB, and then RB is confined to a very narrow range and can be estimated analytically only from S-parameter data, without any special structures or numerical optimization. The proposed method is successfully applied to SiGe HBTs with different device geometries. Results demonstrate that the average error for extracted RB is less than 2.5% over a wide range of bias points. Therefore, we believe that the proposed technique is a reliable routine applicable to estimation of the base resistance for SiGe HBT HICUM model.

The reliability of SiGe HBT under swift heavy ion irradiation

Silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) were irradiated by 25Mev Si4+ ion with equivalent absorbed dose from 300 krad(Si) to 10 Mrad(Si). Pre- and post-irradiation direct current (DC) characteristics were used to quantify the dose tolerance to the heavy ion irradiation. Base current was found more sensitive than collector current and current gain appeared to decline with the ion fluence increasing. An unexpected increase in emitter current was observed in the reversed-mode operation. The reverse leakage current of base-collector and base-emitter junction increased with the increase in ion fluence. The displacement damages were thought to be mainly contributed to performance degradation of SiGe HBT.

A practical noise parameter measurement method of packaged Low noise transistor

The key issue of packaged Low noise transistor noise parameter characterization is test fixture, this paper describes how to design test fixture and TRL cal standard based on PCB in detail, and also comprehensive verification of test fixture and TRL cal standard in frequency domain and time domain. Whats more, this paper takes advantage of a new ultra-fast noise parameter measurement method with more simplicity, less test time and also more measurement accuracy.