This paper proposes two novel and compact low-power tunable AC amplifiers with ultra-low high-pass corner frequency. The circuits are based on alternative AC capacitively coupled feedback topologies ...using novel implementations leading to better performance in terms of area, power and noise efficiency. This is accomplished by a combination of actively boosting the resistive value of a pseudo-resistor (allowing more than two decades of tuning) and an optimization of the active devices required. Measurement results from a fabricated prototype using a 0.18<inline-formula> <tex-math notation="LaTeX">\mu</tex-math> </inline-formula>m technology are provided to demonstrate the technique. The proposed amplifiers can provide tunable high-pass corner frequencies ranging from 31 mHz<inline-formula> <tex-math notation="LaTeX">\vphantom{_{_{}}}</tex-math> </inline-formula> to 7 Hz, with power consumption as low as 0.425 <inline-formula> <tex-math notation="LaTeX">\mu</tex-math> </inline-formula>W, CMRR of 84 dB, 0.1 mm<inline-formula> <tex-math notation="LaTeX">^{2}</tex-math> </inline-formula> area, 39.7 dB gain, and integrated IRN of 2.42 <inline-formula> <tex-math notation="LaTeX">\mu</tex-math> </inline-formula>V<inline-formula> <tex-math notation="LaTeX">_{\mathrm{rms}}</tex-math> </inline-formula>.
A novel architecture for an AC (i.e. high‐pass) amplifier is proposed allowing a drastic reduction of the cutoff frequency to the sub‐Hertz range. It builds upon the classic AC configuration with a ...high gain amplifier and a parallel RC circuit in the feedback loop, by increasing the feedback resistance through bootstrapping. Resistance multiplying factors higher than four orders of magnitude are easily achievable. The basic principle can be applied to several practical implementations, though in this letter it is demonstrate with measurement results of an op‐amp based discrete implementation.
A novel approach to design low-power area-efficient rail-to-rail output single-stage class-AB operational transconductance amplifiers (OTAs) with enhanced large-and small-signal performance to drive ...large capacitive loads is presented. It is based on a non-linear nested current mirror at the active load of a splitted differential input pair biased in weak inversion that boosts dynamic currents beyond their quiescent value directly at the output branch. As a result, slew rate, DC gain, gain-bandwidth product, settling time and noise performance are improved without additional circuit elements or power consumption. An OTA prototype has been fabricated in a 180-nm CMOS process, consuming a quiescent power of 2.9 <inline-formula> <tex-math notation="LaTeX">\mu</tex-math> </inline-formula>W from a supply voltage of <inline-formula> <tex-math notation="LaTeX">\pm</tex-math> </inline-formula>0.5 V and a silicon area of 0.001 mm<inline-formula> <tex-math notation="LaTeX">^{2}</tex-math> </inline-formula>. Measurement results validate the advantages of the proposal, exhibiting positive and negative slew rates of 110 V/ms and <inline-formula> <tex-math notation="LaTeX">-</tex-math> </inline-formula>58 V/ms, respectively, and a gain-bandwidth product of 136 kHz with a phase margin of 90<inline-formula> <tex-math notation="LaTeX">^{\circ}</tex-math> </inline-formula> for a capacitive load of 160 pF.
Gain-Boosted Super Class AB OTAs Based on Nested Local Feedback Beloso-Legarra, Javier; Cruz-Blas, Carlos A. de la; Lopez-Martin, Antonio J. ...
IEEE transactions on circuits and systems. I, Regular papers,
09/2021, Letnik:
68, Številka:
9
Journal Article
Recenzirano
Odprti dostop
A new approach to design super class AB operational transconductance amplifiers (OTAs) with enhanced large-signal and small-signal performance is presented. It is based on employing two nested ...positive and negative feedback loops at the active load of an adaptively biased differential pair in weak inversion region. As a result, DC gain, gain-bandwidth product, settling time and noise are improved compared to conventional super class AB OTAs without extra circuit nodes or power consumption. Measurement results of a 180 nm CMOS test chip prototype show a current boosting factor higher than 5000 and a nearly ideal current efficiency. Due to the ultra-low quiescent currents and high driving capability, the circuit exhibits an excellent large-signal figure-of-merit (FOM L ) of 236 <inline-formula> <tex-math notation="LaTeX">\text{V}^{-1} </tex-math></inline-formula>. To illustrate the applicability of the proposed approach, a differential sample-and-hold (S/H) circuit was designed and fabricated on the same test chip. Measurement results of the S/H validate the advantages of the proposal.
A new method to process the vibration signal acquired by an accelerometer placed in a planetary gearbox housing is proposed, which is useful to detect potential faults. The method is based on the ...phenomenological model and consists of the projection of the healthy vibration signals onto an orthonormal basis. Low pass components representation and Gram-Schmidt's method are conveniently used to obtain such a basis. Thus, the measured signals can be represented by a set of scalars that provide information on the gear state. If these scalars are within a predefined range, then the gear can be diagnosed as correct; in the opposite case, it will require further evaluation. The method is validated using measured vibration signals obtained from a laboratory test bench.
Lymphoplasmacytic lymphoma (LPL) is an indolent mature B-cell-neoplasm with involvement of the bone marrow. At least 90% of LPLs carry MYD88-L265P mutation and some of them (~10%) transform into ...diffuse large B-cell-lymphoma (DLBCL).
Over the past 15 years we have collected 7 cases where the both LPL and DLBCL were diagnosed in the same patient. Clinical records, analytical data and histopathological specimens were reviewed. FISH studies on paraffin-embedded tissue for MYC, BCL2 and BCL6 genes were performed, as well as MYD88-L265P mutation and IGH rearrangement analysis by PCR. A mutational study was done by massive next generation sequencing (NGS).
There were 4 women and 3 men between 36-91 years of age. Diagnoses were made simultaneously in 4 patients. In two cases the LPL appeared before the DLBCL and in the remaining case the high-grade component was discovered 5 years before the LPL. In 6 cases both samples shared the MYD88-L265P mutation. IGH rearrangement analysis showed overlapping features in two of 6 cases tested. Mutational study was evaluable in three cases for both samples showing shared and divergent mutations.
These data suggest different mechanisms of DLBCL development in LPL patients.
It is known that mortality after hip fracture increases compared to the general population; the trend in mortality is a controversial issue. The objective of this study is to examine incidence, ...trends, and factors associated with mortality in patients with osteoporotic hip fractures.
This is a retrospective cohort study that uses the Registry for Hospital Discharges of the National Health System of our hospital. Patients older than 45 having an osteoporotic hip fracture between 1999 and 2015 were identified. Demographic data and comorbidities were obtained. A survival analysis was performed (Cox regression and Kaplan-Meier). Incidence rate, standardized death rate (SDR), trend (Poisson regression), and risk (hazard ratio) were calculated.
During 1999-2015, in our hospital, there were a total of 3992 patients admitted due to osteoporotic hip fracture. Out of these 3992 patients, 3109 patients (77.9%) were women with an average age of 84.47 years (SD 8.45) and 803 (22.1%) were men with an average age of 81.64 years (SD 10.08). The cumulative incidence of mortality was 69.38%. The cumulative mortality rate for 12 months was 33%. The annual mortality was 144.9/1000 patients/year. The 1-year mortality rate increased significantly by 2% per year (IRR 1.020, CI95% 1.008-1.033). The median overall survival was 886 days (CI95% 836-951). The probability of mortality density for a period of 10 years following a hip fracture was 16% for women and 25% for men (first 90 days). The SDR was 8.3 (CI95% 7.98-8.59). Variables that showed statistically significant association with mortality were aged over 75, masculine, institutionalization, mild to severe liver disease, chronic kidney disease, COPD, dementia, heart failure, diabetes, the Charlson Index > 2 , presence of vision disorders and hearing impairment, incontinence, and Downton scale.
For the last 17 years, an increase of mortality for patients with hip fracture and a higher mortality rate in men than in women were observed. Institutionalization combined with comorbidities is associated with a higher mortality.
A novel current-mode CMOS RMS-to-DC converter using translinear techniques is introduced. It is based on a squarer/divider cell that is implemented using an electronically simulated loop with a novel ...biasing scheme that allows its operation in two quadrants. The cell is designed using a differential input current and a small signal first order filter to implement the voltage averaging, leading to a compact solution that can be used with low voltage supplies. The converter has been fabricated in a standard 130-nm CMOS process, and measurement results are provided to demonstrate the feasibility of the system.
For J‐hermitian operators on a Krein space (K,J) satisfying an adequate Fredholm property, a global Krein signature is shown to be a homotopy invariant. It is argued that this global signature is a ...generalization of the Noether index. When the Krein space has a supplementary Real structure, the sets of J‐hermitian Fredholm operators with Real symmetry can be retracted to certain of the classifying spaces of Atiyah and Singer. Secondary Z2‐invariants are introduced to label their connected components. Related invariants are also analyzed for J‐unitary operators.
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