Simple quadrature oscillator for BIST

A simple quadrature oscillator for the built-in self-test (BIST) of integrated analogue filters is proposed. A new hardware-efficient approach for amplitude control is described, the main assets being: (i) the technique requires little hardware, which makes it very useful for BIST; (ii) the oscillation amplitude is well defined, and (iii) the distortion-level introduced by the amplitude control loop is under the control of the designer

Method for electric field and potential calculations in Hall plates

Electrostatic field problems occurring in Hall plates are difficult to solve, mainly because of a non-standard boundary condition defining an oblique angle of the electric field w.r.t. an isolating boundary. A new approach for solving Hall-related field problems is presented. Compared to prior approaches, the technique leads more easily to closed-form expressions for the electric field, and allows obtaining voltage-related Hall characteristics in numerically well conditioned forms

A closed-loop digitally controlled MEMS gyroscope with unconstrained Sigma-Delta force-feedback

In this paper, we describe the system architecture and prototype measurements of a MEMS gyroscope system with a resolution of 0.025 degrees/s/root Hz. The architecture makes extensive use of control loops, which are mostly in the digital domain. For the primary mode both the amplitude and the resonance frequency are tracked and controlled. The secondary mode readout is based on unconstrained Sigma Delta force-feedback, which does not require a compensation filter in the loop and thus allows more beneficial quantization noise shaping than prior designs of the same order. Due to the force-feedback, the gyroscope has ample dynamic range to correct the quadrature error in the digital domain. The largely digital setup also gives a lot of flexibility in characterization and testing, where system identification techniques have been used to characterize the sensors. This way, a parasitic direct electrical coupling between actuation and readout of the mass-spring systems was estimated and corrected in the digital domain. Special care is also given to the capacitive readout circuit, which operates in continuous time

A dual-mass capacitive-readout accelerometer operated near pull-in

A mechanical two-mass configuration and a readout circuit for a single-axis capacitive-readout accelerometer with ΣΔ force-feedback is presented. The system reduces electrical and quantisation input-referred noise through the use of negative springs, reduced gaps in the readout capacitors and maximised readout voltage. A theoretical analysis and simulation results are discussed

Passive loop filter assistance for CTSDMs

This paper presents a power reduction technique for continuous time sigma delta modulators (CTSDM). The approach consists of two elements. First, a passive low pass filter is added in front of the modulator's loop filter to reduce the high frequency components in the loop. As a result, the slew rate requirements of the opamps can be greatly reduced which allows a significant power saving. Unfortunately, the insertion of this low pass filter also changes the modulator's loop gain, and hence affects the NTF and STF (Noise- and Signal Transfer Functions), in an undesired way. Therefore, the second proposed element consists of inserting a compensation branch which is such that the original loop gain, NTF and STF are restored. Thanks to this, our power saving technique is completely transparent on the system level such that all established techniques and toolboxes for CTSDM design can still be used. The technique is especially suited for one-bit CTSDMs where the amount of high-frequency components in the loop is excessive. To showcase the technique, an SOSDM (which is a dedicated type of one-bit CTSDM) was implemented in a 65nm CMOS process. It achieves a peak SNDR of 63dB over a 20MHz bandwidth at a power consumption of 1.7mW while occupying a very small chip area of only 0.009 mm\textsuperscript{2

Folded-cascode amplifier with efficient feedforward gain-boosting

An efficient implementation of a two-stage feedforward amplifier is proposed. The new amplifier topology boosts the DC gain of a folded-cascode amplifier by adding a gain path, which makes use of the 'free' transconductance of the folding current sources. Only a single differential pair is used to convert the input voltage to a current. A current splitter extracts the parts needed for feedforward and for the first gain stage. This turns out to be favourable in terms of noise when compared with more traditional feedforward amplifiers

A very compact 1MS/s Nyquist-rate A/D-converter with 12 effective bits

We present a very compact analog-to-digital convertor (ADC) for use as a standard cell. To achieve an inherent accuracy of at least 12-bits without trimming or calibration, extended counting A/D-conversion is used. Here, the circuit performs a conversion by passing through two modes of operation: first it works as a 1st-order incremental convertor and then it is reconfigured to operate as a conventional algorithmic converter. This way, we obtain a Nyquist-rate converter that requires only 1 operational amplifier and achieves 12-bit accuracy performance in 13 clock cycles with 9 bit capacitor matching. The circuit is designed in 0.18 mu m CMOS with a thick oxide option. The resulting analog core occupies a chip area of only 0.011 mm2 and the complete digital control and reconstruction logic (including additional test features and storage registers) is 0.02 mm2. The analog blocks of the circuit consume 1.2mW and the digital 0.4mW. At a sample rate of 1 MS/s, the peak SNDR is 74.5dB and the dynamic range is 78dB, constant over the Nyquist band. The worst-case integral non-lineairity (INL) is within plus or minus 0.55 LSB

Nuclear DDX3 expression predicts poor outcome in colorectal and breast cancer

Purpose: DEAD box protein 3 (DDX3) is an RNA helicase with oncogenic properties that shuttles between the cytoplasm and nucleus. The majority of DDX3 is found in the cytoplasm, but a subset of tumors has distinct nuclear DDX3 localization of yet unknown biological significance. This study aimed to evaluate the significance of and mechanisms behind nuclear DDX3 expression in colorectal and breast cancer. Methods: Expression of nuclear DDX3 and the nuclear exporter chromosome region maintenance 1 (CRM1) was evaluated by immunohistochemistry in 304 colorectal and 292 breast cancer patient samples. Correlations between the subcellular localization of DDX3 and CRM1 and the difference in overall survival between patients with and without nuclear DDX3 were studied. In addition, DDX3 mutants were created for in vitro evaluation of the mechanism behind nuclear retention of DDX3. Results: DDX3 was present in the nucleus of 35% of colorectal and 48% of breast cancer patient samples and was particularly strong in the nucleolus. Nuclear DDX3 correlated with worse overall survival in both colorectal (hazard ratio [HR] 2.34, P<0.001) and breast cancer (HR 2.39, P=0.004) patients. Colorectal cancers with nuclear DDX3 expression more often had cytoplasmic expression of the nuclear exporter CRM1 (relative risk 1.67, P=0.04). In vitro analysis of DDX3 deletion mutants demonstrated that CRM1-mediated export was most dependent on the N-terminal nuclear export signal. Conclusion: Overall, we conclude that nuclear DDX3 is partially CRM1-mediated and predicts worse survival in colorectal and breast cancer patients, putting it forward as a target for therapeutic intervention with DDX3 inhibitors under development in these cancer types