A low noise capacitance to voltage readout circuit based on active feedback charge sensitive amplifier for micro-gyro.

Trans-impedance amplifier (TIA) based capacitance-voltage (C-V) readout circuits are widely used in micro-machined gyroscopes' control system. In this work, the noise performance of a TIA and charge sensitive amplifier (CSA) based C-V readout circuit is analyzed in detail. The theoretical derivation and simulation experiments carried out in this paper show that the thermal noise of high value feedback resistors in TIA dominates the output noise of the circuit, while a CSA-based readout circuit can overcome this shortcoming. Then, a CSA-based C-V readout circuit is designed with a 1.8 V transistor on a 180 nm complementary metal-oxide-semiconductor. This C-V-based readout circuit occupies an area of 0.039 mm2, which is smaller than the area of a 0603 package resistor. When 1 V bias voltage (Vb) is added to the capacitors under test, the tested C-V gain of this circuit is as high as 225 dB, and the tested output noise of the circuit is less than 150 nV/Hz. Finally, the fabricated chip achieved a resolution of 840 zF/Hz at Vb as low as 1 V. This CSA-based C-V readout circuit has more advantages in terms of noise and area over the TIA circuit and is more suitable for integration into the interface integrated circuit for micro-gyroscopes.

A capacitance sensing method with trans-impedance based readout circuit and adaptive filtering for micro-gyro.

Trans-impedance amplifier (TIA) based capacitance-voltage (C-V) readout circuit is an attractive choice for micro-machined gyroscope for its simplicity and superior performance. In this work, the noise and the C-V gain characteristics of the TIA circuit are analyzed in detail. Then, a TIA based readout circuit with a C-V gain of about 286 dB is designed, and a series of experiments are conducted to test the performance of the circuit. Both the analysis and test results show that T-network TIA should be avoided as far as possible for its poor noise performance. All results also show that there is a signal-to-noise ratio (SNR) limit for the TIA based readout circuit, and the SNR can only be further improved by filtering. Hence, an adaptive finite impulse response filter is designed to further improve the SNR of the sensed signal. For a gyroscope with a peak-to-peak variable capacitance of about 200 aF, a SNR of 22.8 dB can be achieved by the designed circuit and a SNR of 47 dB can be obtained by further adaptive filtering. Finally, the solution presented in this paper achieves a capacitive sensing resolution of 0.9 aF.

Real-time signal processing in field programmable gate array based digital gamma-ray spectrometer.

Field programmable gate arrays (FPGAs) are attractive for a digital spectrometer due to its advantages of digital signal processing. However, how to improve the versatility of the spectrometer and increase the operating frequency of the digital shaper has gradually become a limitation that needs to be resolved in the FPGA-based spectrometer. A solution to improve the universality of the FPGA-based digital spectroscopy system is presented in this work, and the implementation of the real-time digital signal processing unit is improved to obtain a higher operating frequency, and then the optimal parameters of the digital trapezoidal shaper and the processing unit are also discussed through a series of experiments; finally, a FPGA-based digital spectrometer is developed. With the HPGe detector, the spectrometer achieves excellent energy resolution performance of 0.35% at 662 keV, 0.25% at 1173.2 keV, and 0.23% at 1332.5 keV.

Autologous hematopoietic stem cell transplantation in chemotherapy-sensitive lymphoblastic lymphoma: treatment outcome and prognostic factor analysis.

OBJECTIVE: The study evaluated the effectiveness of autologous hematopoietic stem cell transplantation (AHSCT) in the treatment of lymphoblastic lymphoma (LL). METHODS: We retrospectively analyzed the data from 41 patients with chemotherapy-sensitive LL who underwent hematopoietic stem cell transplantation (HSCT) from December 1989 to December 2009 in a single institution. RESULTS: HSCT was conducted as first-line consolidation therapy and salvage therapy in 36 and 5 patients, respectively. The median follow-up was 97.1 months (range, 24.6-173.1 months). The 5-year overall survival (OS) and event-free survival (EFS) rate were 64% and 47% for the initially treated patients, respectively, and were both 20% for the relapsed ones. Bone marrow (BM) involvement and chemotherapy cycles prior to transplantation were identified as significant prognostic factors for EFS in multivariate analysis. CONCLUSIONS: These results confirm that AHSCT is a reasonable option for chemotherapy-sensitive LL patients in first complete remission (CR1).