Transformer-Coupled Power Amplifier Stability and Power Back-Off Analysis

We present a mathematical analysis of the common-mode instability and power back-off feature of a transformer-coupled Class-AB differential power amplifier (PA). The efficient impedance matching of the transformer combiner and efficiency improvement at power back-off, a major benefit of this structure, are illustrated. In addition, an analytical model is derived to predict the common-mode oscillations in PA. The analytical results, based on a simple hand-calculation model for the transistor, show good agreement with simulation results using complete 90-nm models. Two methods to suppress the common-mode oscillations are investigated and analyzed in detail.     

On gate leakage current partition for MOSFET compact model

Aggressive scaling of the gate-oxide thickness has made gate-tunneling current an essential aspect of MOSFET modeling and this leakage current density continues to increase for every process generation. Accurate compact models for gate-tunneling current and its source/drain partition are extremely critical to valid circuit performance in the 90 nm technology or beyond. Gate current partition has been studied by several authors [Cao K, et al. “BSIM4 gate leakage model including source–drain partition,” in IEDM Tech. Dig., San Francisco, CA, Dec. 2000. p. 815–8; R. van Langevelde et al., Gate current: modeling, ΔL extraction and impact on RF performance, in IEDM Tech. Dig., Washington, DC, Dec. 2001. p. 289–92; Shih W-K, et al., “A general partition scheme for gate leakage current suitable for MOSFET compact models,” in IEDM Tech. Dig., Washington DC., Dec. 2001. p. 293–6]. In this paper, an insight on the common/difference of these different gate leakage current partition schemes into source/drain has been provided and the accuracy of BSIM4 [Cao K, et al. “BSIM4 gate leakage model including source–drain partition,” in IEDM Tech. Dig., San Francisco, CA, Dec. 2000. p. 815–8] partition scheme is confirmed with comparing to the new derived equation, which incorporates the gate current into the inhomogeneous term calculation.     

A 5.8 GHz 1 V Linear Power Amplifier Using a Novel On-Chip Transformer Power Combiner in Standard 90 nm CMOS

A fully integrated 5.8 GHz Class AB linear power amplifier (PA) in a standard 90 nm CMOS process using thin oxide transistors utilizes a novel on-chip transformer power combining network. The transformer combines the power of four push-pull stages with low insertion loss over the bandwidth of interest and is compatible with standard CMOS process without any additional analog or RF enhancements. With a 1 V power supply, the PA achieves 24.3 dBm maximum output power at a peak drain efficiency of 27% and 20.5 dBm output power at the 1 dB compression point.     

A CMOS IR-UWB Transceiver Design for Contact-Less Chip Testing Applications

This paper presents a novel CMOS impulse radio (IR) ultra-wide-band (UWB) transceiver system design for future contact-less chip testing applications using inductive magnetic coupling as wireless interconnect. The proposed architecture is composed of a simple and robust design of a Gaussian monocycle impulse generator at the transmitter, a wideband short-range on-chip transformer for data transmission, and a g_m-boosted common-gate low-noise amplifier in the UWB receiver path. SpectreRF post-layout simulation with a 90-nm CMOS technology shows that the transceiver operates up to a 5 Gb/s data rate, and consumes a total of 9 mW under a 1-V power supply.     

Millimeter-wave CMOS design

This paper describes the design and modeling of CMOS transistors, integrated passives, and circuit blocks at millimeter-wave (mm-wave) frequencies. The effects of parasitics on the high-frequency performance of 130-nm CMOS transistors are investigated, and a peak f/sub max/ of 135 GHz has been achieved with optimal device layout. The inductive quality factor (Q/sub L/) is proposed as a more representative metric for transmission lines, and for a standard CMOS back-end process, coplanar waveguide (CPW) lines are determined to possess a higher Q/sub L/ than microstrip lines. Techniques for accurate modeling of active and passive components at mm-wave frequencies are presented. The proposed methodology was used to design two wideband mm-wave CMOS amplifiers operating at 40 GHz and 60 GHz. The 40-GHz amplifier achieves a peak |S/sub 21/| = 19 dB, output P/sub 1dB/ = -0.9 dBm, IIP3 = -7.4 dBm, and consumes 24 mA from a 1.5-V supply. The 60-GHz amplifier achieves a peak |S/sub 21/| = 12 dB, output P/sub 1dB/ = +2.0 dBm, NF = 8.8 dB, and consumes 36 mA from a 1.5-V supply. The amplifiers were fabricated in a standard 130-nm 6-metal layer bulk-CMOS process, demonstrating that complex mm-wave circuits are possible in today's mainstream CMOS technologies.     

Corrosion of Alloy Steel in 30% Ethylene Glycol Solution and CrO_4~（2-） Under Hydrodynamic Condition

 The electrochemical behavior of steel alloy in 30% ethylene glycol-water solution at different solution rotating speeds was investigated by polarization curves and AC impedance measurements. The results obtained showed that corrosion rate did not change significantly at different rotating speeds. The effect of chromate as the inhibitor was studied and high inhibition efficiency was obtained. It was found that surface passivation occurred in the presence of the inhibitor. The inhibiting effect of the chromate was explained on the basis of the competitive adsorption between the inorganic anions and the aggressive Cl- and the adsorption isotherm basically obeys the Langmuir adsorption isotherm. Thermodynamic parameters for inhibitor adsorption were determined and results reveal that the adsorption process is spontaneous.     

Design of a Sub-mW 960-MHz UWB CMOS LNA

This paper presents a sub-mW ultra-wideband (UWB) fully differential CMOS low-noise amplifier (LNA) operating below 960 MHz for sensor network applications. By utilizing both nMOS and pMOS transistors to boost the transconductance, coupling the input signals to the back-gates of the transistors, and combining the common-gate and shunt-feedback topologies, the LNA achieves 13 dB of power gain, a 3.6 dB minimum noise figure, and -10 dBm of IIP3 with only 0.72 mW of power consumption from a 1.2 V supply     

A correlation-based model for predicting gas extraction performance in a copper converting plant

To help improve hygiene in a copper smelter building, a correlation-based computer model of the gas extraction system was developed and used in conjunction with experimental observations to investigate the effects of process parameters on extraction performance. The model predicted that 28% of the total flow originated from in-leakage, and reduction of the in-leakage would cause a nearly equivalent amount of infiltration through the converter hoods, thus reducing fugitive emissions. It was also found that improved operational practices (closing and maintaining hood gages, isolating converters on standby) could double the draft within the converter hoods while decreasing the total flow rate by nearly 10%.