Temperature Coefficient Bias Research Articles

A Compact V-Band Temperature Compensation Low-Noise Amplifier in a 130 nm SiGe BiCMOS Process.

This paper presents a compact V-band low-noise amplifier (LNA) featuring temperature compensation, implemented in a 130 nm SiGe BiCMOS process. A negative temperature coefficient bias circuit generates an adaptive current for temperature compensation, enhancing the LNA's temperature robustness. A T-type inductive network is employed to establish two dominant poles at different frequencies, significantly broadening the amplifier's bandwidth. Over the wide temperature range of -55 °C to 85 °C, the LNA prototype exhibits a gain variation of less than 1.5 dB at test frequencies from 40 GHz to 65 GHz, corresponding to a temperature coefficient of 0.01 dB/°C. At -55 °C, 25 °C, and 85 °C, the measured peak gains are 25.5 dB, 25 dB, and 24.4 dB, respectively, with minimum noise figures (NF) of 3.0 dB, 3.5 dB, and 4.2 dB, and DC power consumptions of 22.3 mW, 27.6 mW, and 34.4 mW. Moreover, the total silicon area of the LNA chip is 0.37 mm2, including all test pads, while the core area is only 0.09 mm2.

Research on Low Temperature Drift Suppression of Micro-Machined Gyroscope Based on Self-Calibration Technology

Micro-machined gyroscope is an important inertial sensor, which has the advantages of high integration, small size and low power consumption. However, due to the temperature sensitivity of silicon and electronic devices, the bias and scale factor of micro-machined gyroscopes have temperature drift, which limits their engineering application the relatively large process error of micro-machining makes the frequency mismatch between driving mode and detection mode of micro-machined gyroscope, which not only deteriorates the mechanical sensitivity of the gyroscope, but also causes the frequency mismatch between driving mode and detection mode, it also leads to the quadrature error of driving coupling in gyro detection mode. Based on this, firstly, the relationship between the bias factor and the scale factor of MEMS gyroscope and its dynamic and electrical parameters is analyzed. Secondly, a self-calibration capacitance detection scheme based on triangular-electrode based (TEB) is proposed, and the temperature effect of the scheme is analyzed. Finally, the simulation results show that the temperature coefficient of the scale factor decreases from −8845 ppm/°C to 1660 ppm/°C when the temperature range is from −10 °C to 60 °C, the bias temperature coefficient decreased from −0.97°/s/°C to −0.42°/s/°C. The experimental results show that the scheme effectively reduces the temperature sensitivity of the bias and scale factor of the gyroscope.

Bias Modulation of Force-to-Rebalanced Micro Hemispherical Resonator Gyroscope Based on Mode-Rotation

This paper presents a bias modulation method for the force-to-rebalanced (FTR) micro hemispherical resonator gyroscope ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> HRG) based on the mode-rotation, which is achieved by regulating the gyroscope’s drive and sense modes revolving at an assigned rate. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> HRG output under the mode-rotation includes the sinusoidally modulated bias and a rotation-induced DC bias. Accordingly, the alternating mode-rotation is proposed to chop the DC rate bias into square waves. By this approach, errors in the DC component from the scale factor drift are also modulated. The open-loop and closed-loop relationships between the rotation actuating force and the mode-rotation rate are investigated by theoretical analyses and numerical simulations. The lower and upper bounds of the rotation rate and the alternating frequency are discussed under the considerations of the error changing rate, the forcer capacity, the maximum voltage, the resonator momentum, and the measurement range. In addition, the controllers in the amplitude, quadrature, and inclination loops utilize the proportional-integral-resonance (PIR) regulating law to suppress the sinusoidal-varying errors introduced by the assigned rotation. The proposed bias modulation method was experimentally verified by a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> HRG with an FPGA platform. The results suggest the alternating mode-rotation improved the bias temperature coefficient by 12 times over the rotation-free FTR architecture. For a three-hour measurement at room temperature, the rate-integration of the mode alternately rotated FTR was within 50 degrees. In comparison, the rate-integration of the rotation-free FTR diverged over 600 degrees due to the bias drift. The presented bias modulation method can be utilized in axisymmetric gyroscopes, such as hemispherical, ring/disk, quad-mass gyroscopes, etc.

Design and verification of a structure for isolating stress in sandwich MEMS accelerometer

In this paper, a structure for isolating packaging stress in a sandwich MEMS capacitive accelerometer is proposed and verified. The structure is designed and analyzed by finite element modeling (FEM) using ABAQUS. Two kinds of MEMS accelerometer, one with the stress isolation structure and the other without it, were simulated and compared. Simulation results show that the structure can reduce packaging stress and avoid uneven stress distribution. And then, MEMS accelerometers with and without the stress isolation structure are fabricated based on bulk micromachining technology and experimentally verified. The experimental results show that stabilities of the bias temperature coefficient and scale factor temperature coefficient of the MEMS accelerometer with the stress isolation structure are significantly improved. The comparison results demonstrate that the stress isolating structure is working and the packaging stress is successfully isolated.

Temperature based analysis of 3-step field plate AlGaN/GaN HEMT using numerical simulation

In this work, temperature based instability of the 3-step field plate (FP) AlGaN/GaN HEMT has been explored using ATLAS TCAD. DC performance characteristics such as: drain current, trans-conductance and Ion/Ioff ratio at different temperatures (ranging from 300 K to 500 K) and GaN channel thicknesses (from 150 nm to 500 nm) have been investigated. It has been observed that, drain current decreases with rise in temperature with a coefficient of approximately −0.0031 mA μm−1 K−1. Subsequently, impact of temperature on breakdown voltage, electric field, electron temperature and parasitic capacitances has also been investigated. Enhancement in breakdown voltage and reduction in trans-conductance has been observed with rise in temperature for above zero temperature coefficient bias point. Along with temperature variation, impact of GaN channel, AlGaN barrier thickness and mole fraction of aluminium concentration has also been studied and it is seen that breakdown voltage and Ion/Ioff increases for thinner channel and barrier thickness.

Effect of excitation voltage on bias temperature coefficient of MEMS sandwich accelerometer

In MEMS closed-loop accelerometer, excitation voltage is an important design parameter that is related to many performance indexes, and the bias temperature coefficient is a key point for MEMS accelerometer. But the effect of excitation voltage on bias temperature coefficient is not clear and their relation has not yet been established. This paper studies the effect of excitation voltage on bias temperature coefficient of MEMS sandwich accelerometer. The mechanism of their relation is point out, and experiments of bias temperature drift with different excitation voltages are carried out. The measured results show that the excitation voltage influences the bias temperature coefficient of MEMS sandwich accelerometer greatly, and the frame of sensor structure is the main source of bias temperature drift in MEMS sandwich accelerometer. This paper is also helpful for researchers to further understand the source of bias drift in MEMS sandwich accelerometer and make corresponding improvement.

A Fully Passive RFID Temperature Sensor SoC With an Accuracy of ±0.4 °C ($3\sigma$ ) From 0 °C to 125 °C

This paper presents a fully passive 13.56 -MHz RFID temperature sensor system-on-chip. Its power management unit operates over a large temperature range using a zero temperature coefficient bias source. On-chip temperature sensing is accomplished with low-voltage, low-power CMOS circuitry, and time-domain signal processing. Two readout commands have been defined to study supply noise sensitivity: 1) standard readout, where just a single set of data is transferred to the reader and 2) serial readout, where several sets of data are sent one after the other to the reader. With the standard readout command, the sensor suffers from interference from the RFID command packet and outputs interference as well, while the sensor outputs no interference with the serial readout command. Measurements show that sensor resolution with serial readout is improved by a factor of approximately 16 compared to standard readout. The chip was fabricated in a standard 0.35- $ \mu \text{m}$ CMOS technology and chip-on-board mounted to a tuned RFID transponder coil on an aluminum core FR4 PCB substrate. Real-time wireless temperature sensing has been demonstrated with a commercial HF RFID reader. With a two-point calibration, the SoC achieves a ${3\sigma }$ sensing accuracy of ±0.4 °C from 0 °C to 125 °C.

Design and Experiment of Dual-Mass MEMS Gyroscope Sense Closed System Based on Bipole Compensation Method

This paper presents a sense mode closed-loop method for dual-mass micro-electro-mechanical system (MEMS) gyroscope based on the bipole temperature compensation method. A pair of conjugate poles are investigated as the bottle neck of the sense closed-loop system of MEMS gyroscope, and the bipole temperature compensation proportional controller (BTCPC) is employed to realize the closed-loop: a pair of additional conjugate zeros are utilized to generate bipoles with poles. Since poles changes with temperature, thermal resistance is utilized in BTCPC to make zeros variable with temperatures. The BTCPC is designed very carefully to make the system have enough bandwidth and better performance. The overall gyroscope model is established and simulated either in the time domain or the frequency domain, and the results verify that the sense closed-loop works rapidly and steadily. The system is realized on PCBs and is tested on the turntable in temperature oven. The experimental results show that the bias stability, angular random walking, bias temperature coefficient, and the bandwidth values of sense open-loop and closed-loop are 2.168 °/h, 0.155 °/%/h, 9.534 °/h/°C, 13 Hz, and 2.168 °/h, 0.140 °/%/h (five tests average value), 5.991 °/h°C, 61 Hz, respectively.

Design and Implementation of a Micromechanical Silicon Resonant Accelerometer

The micromechanical silicon resonant accelerometer has attracted considerable attention in the research and development of high-precision MEMS accelerometers because of its output of quasi-digital signals, high sensitivity, high resolution, wide dynamic range, anti-interference capacity and good stability. Because of the mismatching thermal expansion coefficients of silicon and glass, the micromechanical silicon resonant accelerometer based on the Silicon on Glass (SOG) technique is deeply affected by the temperature during the fabrication, packaging and use processes. The thermal stress caused by temperature changes directly affects the frequency output of the accelerometer. Based on the working principle of the micromechanical resonant accelerometer, a special accelerometer structure that reduces the temperature influence on the accelerometer is designed. The accelerometer can greatly reduce the thermal stress caused by high temperatures in the process of fabrication and packaging. Currently, the closed-loop drive circuit is devised based on a phase-locked loop. The unloaded resonant frequencies of the prototype of the micromechanical silicon resonant accelerometer are approximately 31.4 kHz and 31.5 kHz. The scale factor is 66.24003 Hz/g. The scale factor stability is 14.886 ppm, the scale factor repeatability is 23 ppm, the bias stability is 23 μg, the bias repeatability is 170 μg, and the bias temperature coefficient is 0.0734 Hz/°C.

Amplifier Bias Stability Design on Output Range Temp. Coefficient

The limitations of empiric design methods for amplifier biasing stability were pointed out. Critical bias and output range of voltage divider biasing amplifier were discussed. The relationship between bias temperature coefficient and β temperature coefficient was discussed as well. The ratio of bias temperature coefficient to β temperature coefficient is defined as effecting factor. Amplifier bias stability is designed based on output range temperature coefficient. The methods for designing base biasing resistance of voltage divider biasing amplifier on the basis of output range temperature coefficient and for analyzing biasing stability of this amplifier are introduced.

Mutual compensation of mobility and threshold voltage temperature effects with applications in CMOS circuits

Mutual compensation of mobility and threshold voltage temperature variations may result in a zero temperature coefficient bias point of a MOS transistor. The conditions under which this effect occurs, and stability of this bias point are investigated. Possible applications of this effect include voltage reference circuits and temperature sensors with linear dependence of voltage versus temperature. The theory is verified experimentally investigating the temperature behavior of a simple voltage reference circuit realized in 0.35 /spl mu/m CMOS process.

Neutron Multiplication Factors as a Function of Temperature: A Comparison of Calculated and Measured Values for Lattices Using233UO2-ThO2Fuel in Graphite

Neutron multiplication factors calculated as a function of temperature for three graphite-moderated /sup 233/UO/sub 2/-ThO/sub 2/-fueled lattices are correlated with the values measured for these lattices in the high-temperature lattice test reactor (HTLTR). The correlation analysis is accomplished by fitting calculated values of k/sub infinity/(T) to the measured values using two least-squares-fitted correlation coefficients: (a) a normalization factor and (b) a temperature coefficient bias factor. These correlations indicate the existence of a negative (nonconservative) bias in temperature coefficients of reactivity calculated using ENDF/B-IV cross-section data. Use of an alternate cross-section data set for thorium, which has a smaller resonance integral than ENDF/B-IV data, improved the agreement between calculated and measured temperature coefficients of reactivity for the three experimental lattices. The results of the correlations are used to estimate the bias in the temperature coefficient of reactivity calculated for a lattice typical of fresh /sup 233/U recycle fuel for a high-temperature gas-cooled reactor (HTGR). This extrapolation to a lattice having a heavier fissile loading than the experimental lattices is accomplished using a sensitivity analysis of the estimated bias to alternate thorium cross-section data used in calculations of k/sub infinity/(T). The envelope of uncertainty expected to contain the actual values for themore » temperature coefficient of the reactivity for the /sup 233/U-fueled HTGR lattice studied remains negative at 1600 K (1327/sup 0/C). Although a broader base of experimental data with improved accuracy is always desirable, the existing data base provided by the HTLTR experiments is judged to be adequate for the verification of neutronic calculations for the HTGR containing /sup 233/U fuel at its current state of development.« less