Zhenrong Jin

Transistor noise in SiGe HBT RF technology

This brief presents experimental and modeling results of device noise in SiGe HBT RF technology. By careful bandgap engineering, a simultaneous reduction of RF noise, 1/f noise, and phase noise has been achieved. At a given I/sub B/, transistors with different base bandgap profiles show similar 1/f noise. At a given I/sub C/, however, transistors with a higher /spl beta/ (and hence lower RF noise) show lower 1/f noise. Circuit analysis and simulation shows that the phase noise is reduced as well.

A low-power ka-band Voltage-controlled oscillator implemented in 200-GHz SiGe HBT technology

An integrated low-power low phase-noise Ka-band differential voltage-controlled oscillator (VCO) is developed in a 0.12-/spl mu/m 200-GHz silicon-germanium heterojunction bipolar transistor technology. The use of line inductors instead of transmission lines is demonstrated to be feasible in LC-tuned resonators for Ka-band applications. This VCO can operate from a supply voltage of 1.6-2.5 V. A single-sideband phase noise of -99 dBc/Hz at 1-MHz offset from the carrier frequency of 33 GHz is achieved, together with a VCO figure-of-merit of -183.7 dBc/Hz. The frequency tuning constant of the VCO in the linear regime is -0.547 GHz/V.

Proton radiation response of SiGe HBT analog and RF circuits and passives

Presents the first experimental results of the effects of 63 MeV proton irradiation on SiGe heterojunction bipolar transistor (HBT) analog and radio-frequency (RF) circuits and passive elements. A SiGe HBT bandgap, reference circuit, commonly used to generate stable on-chip voltages in analog ICs, a SiGe HBT voltage-controlled oscillator, a key building block for RF transceivers, and an LC bandpass filter routinely used in RF circuit design were each irradiated to proton fluences as high as 5/spl times/10/sup 13/ p/cm/sup 2/. The degradation associated with these extreme proton fluences was found to be minimal, suggesting that SiGe HBT technology is robust for these types of circuit applications.

1/f noise in proton-irradiated SiGe HBTs

Investigates the impact of proton irradiation on the 1/f noise in ultra-high-voltage chemical-vapor deposition SiGe heterojunction bipolar transistors. The relative degradation of 1/f noise shows a strong dependence on device geometry. Both the geometry dependence and the bias dependence of 1/f noise change significantly after exposure to 2/spl times/10/sup 13/ p/cm/sup 2/ protons. An expression describing the 1/f noise is derived and used to explain the experimental observations.

Impact of geometrical scaling on low-frequency noise in SiGe HBTs

The influence of geometrical scaling on low-frequency noise in SiGe HBTs is presented. Small-size transistors show a strong variation in noise across many samples, whereas the noise in larger devices is more statistically reproducible. This size-dependent variation in noise can produce challenges for accurate compact modeling. This effect is investigated using reverse-bias emitter-base stress and calculations based on the superposition of generation/recombination noise.

On the high-temperature (to 300/spl deg/C) characteristics of SiGe HBTs

A comprehensive investigation of the high-temperature characteristics of advanced SiGe heterojunction bipolar transistors (HBTs) is presented, and demonstrates that, contrary to popular opinion, SiGe HBTs are potentially well-suited for many electronics applications operating at temperatures as high as 300/spl deg/C.

Modeling and characterization of SiGe HBT low-frequency noise figures-of-merit for RFIC applications

We present the first systematic experimental and modeling results of noise corner frequency (f/sub C/) and noise corner frequency to cutoff frequency ratio (f/sub C//f/sub T/) for SiGe heterojunction bipolar transistors (HBTs) in a commercial SiGe RF technology. The f/sub C/ and f/sub C//f/sub T/ ratio are investigated as a function of operating collector current density, SiGe profile, breakdown voltage, and transistor geometry. We demonstrate that both the f/sub C/ and f/sub C//f/sub T/ ratio can be significantly reduced by careful SiGe profile optimization. A comparison of the f/sub C/ and f/sub C//f/sub T/ ratio for high breakdown and standard breakdown voltage devices is made. Geometrical scaling data show that the SiGe HBT with A/sub E/=0.5/spl times/2.5 /spl mu/m/sup 2/ has the lowest f/sub C/ and f/sub C//f/sub T/ ratio compared to other device geometries. An f/sub C/ reduction of nearly 50% can be achieved by choosing this device as the unit cell in RF integrated-circuit design.

Proton response of low-frequency noise in 0.20 μm 90 GHz fT UHV/CVD SiGe HBTs

Abstract The influence of proton exposure on the low-frequency noise of 0.20 μm UHV/CVD SiGe HBTs is presented. The noise degradation after irradiation shows a strong dependence on transistor geometry. Our previously developed noise theory is used to understand this behavior, and a comparison is made between these new results on third generation SiGe technology and our prior results on the first generation SiGe technology.

An investigation of low-frequency noise in complementary SiGe HBTs

We present a comprehensive investigation of low-frequency noise behavior in complementary (n-p-n + p-n-p) SiGe heterojunction bipolar transistors (HBTs). The low-frequency noise of p-n-p devices is higher than that of n-p-n devices. Noise data from different geometry devices show that n-p-n transistors have an increased size dependence when compared with p-n-p transistors. The 1/f noise of p-n-p SiGe HBTs was found to have an exponential dependence on the (intentionally introduced) interfacial oxide (IFO) thickness at the polysilicon-to-monosilicon interface. Temperature measurements as well as ionizing radiation were used to probe the physics of 1/f noise in n-p-n and p-n-p SiGe HBTs. A weak temperature dependence (nearly a 1/T dependence) of 1/f noise is found in both n-p-n and p-n-p devices with cooling. In most cases, the magnitude of 1/f noise is proportional to I/sub B//sup 2/. The only exception in our study is for noise in the post-radiation n-p-n transistor biased at a low base current, which exhibits a near-linear dependence on I/sub B/. In addition, in proton radiation experiments, the 1/f noise of p-n-p devices was found to have higher radiation tolerance than that of n-p-n devices. A two-step tunneling model and a carrier random-walk model are both used to explain the observed behavior. The first model suggests that 1/f noise may be caused by a trapping-detrapping process occurring at traps located inside IFO, while the second one indicates that noise may be originating from the emitting-recapturing process occurring in states located at the monosilicon-IFO interface.

On the suitability of SiGe HBTs for high-temperature (to 300/spl deg/) electronics

The first comprehensive investigation of the high-temperature operation of SiGe HBTs is presented, and demonstrates that, contrary to popular opinion, SiGe HBTs are well-suited for many electronics applications operating at temperatures as high as 300/spl deg/C.