Yudong Wang

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.

Experimental study of bias dependence of pulsed laser-induced single-event transient in SiGe HBT

Abstract This work presents a comprehensive investigation of single-event transient (SET) in SiGe HBT induced by pulsed laser irradiation at different bias conditions. The impacts of collector voltage VCC and base voltage VB on SET are compared and discussed. Experimental results show that SET in SiGe HBT highly depends on the applied bias conditions during irradiation. The underlying physical mechanisms are analyzed in detail. It is found that the variation of collector transient current approximately satisfies an ideal exponential discharge law. The additional discharge path plays a significant role in collector charge collection and discharge time constant once the transistors arrive at the reverse-active mode.

Extraction of temperature dependences of small-signal model parameters in SiGe HBT HICUM model*

In this work, temperature dependences of small-signal model parameters in the SiGe HBT HICUM model are presented. Electrical elements in the small-signal equivalent circuit are first extracted at each temperature, then the temperature dependences are determined by the series of extracted temperature coefficients, based on the established temperature formulas for corresponding model parameters. The proposed method is validated by a 1 × 0.2 × 16 μm2 SiGe HBT over a wide temperature range (from 218 K to 473 K), and good matching is obtained between the extracted and modeled results. Therefore, we believe that the proposed extraction flow of model parameter temperature dependence is reliable for characterizing the transistor performance and guiding the circuit design over a wide temperature range.

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.

Impact of bias conditions on performance degradation in SiGe HBTs irradiated by 10 MeV Br ion

Abstract Effects of bias conditions on 10xa0MeV Br ion irradiation were investigated in NPN SiGe HBTs. Pre- and post-radiation direct current (DC) characteristics, such as current gain, leakage current, Early voltage and neutral base recombination, were studied and used to quantify the dose tolerance to 10xa0MeV Br ion. Experiment results for different bias conditions were compared and discussed in detail. It is found that performance degradations are indeed bias dependent. The BE junction reversed-biased mode suffers the largest degradation and the case with BE junction forward-biased shows the smallest degradation. The underlying physical mechanisms are analyzed and investigated in present work. The injection annealing effect of displacement damage is found to be responsible for the different irradiation response of SiGe HBTs under three bias conditions.

Offset based feedforward amplifier with nonlinearity compensation and P1dB expansion

This paper presents the design of a 6-path offset based feedforward amplifier with high linearity. It leads to both high order nonlinearity compensation and 1dB compression point (P1dB) expansion at the same time. The structure avoids the use of extra gain stages and the superposition mechanism improves the gain which saves the power. The linearized amplifier was implemented by the 130nm SiGe technology. The experimental results was tested under 1.1GHz input frequency, and shows a 3dBm IIP3, >45dBm HP2 and −11dBm P1dB linearity performance with a nontraditional IM3 slope lower than −3dB/dB within the compensation window. A 15dBm compression point expansion and 19dBm nP3 improvement were achieved. The tested voltage gain was 15.5dB with noise figure around 2.9dB under good input matching condition. The core circuits consume 4.8mW from 1.8V power supply and the chip occupies 0.03mm2 area.

A low phase noise 8.8 GHz VCO based on ISF manipulation and dual-tank technique

This paper presents a novel 8.8 GHz voltage-controlled oscillator (V CO), which employs a dual-tank structure and the impulse sensitivity function (ISF) manipulation technique. By utilizing these techniques, the behavior of both the tail and the cross-coupled transistors is optimized compared to the conventional VCO; therefore, the noise from the transistors and the low quality of tank is reduced; resulting in better phase noise performance. The circuit is implemented in 130nm BiCMOS technology, and achieves −115.26dBc/Hz @ 1MHz offset with 4 percent frequency tuning range. The power consumption is between 80mW and 100mW from a 2.5V power supply, and the figure of merit (FoM) is 175dBc/Hz.

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.

DESIGN OF 900 MHZ SIGE POWER AMPLIFIER WITH LINEARIZATION BIAS CIRCUIT

A single stage 900MHz power amplifier (PA) with linearization bias circuit is designed with HHNEC 0.5μm BIS500G power SiGe BiCMOS process. It is implemented by single-ended common emitter structure as a class AB power amplifier. The adopted active bias circuit is originally explained by using two virtue current sources, so that the mechanism of the improvement of linearity can be described more clearly. Then the mechanism is applied to guide the design of a power amplifier with an active bias circuit, which shows better linearity than resistor biased power amplifier by simulation. Through further design and measurement, the fabricated single stage power amplifier exhibits output power 1 dB compression point (OP1dB) of 18.9 dBm, with power added efficiency (PAE) of 26.75% and power gain of 20.9 dB under 3.3V voltage supply.