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This paper presents the design of an ultra low-voltage (ULV) pseudo operational transconductance amplifier (P-OTA) that is able to operate with a single supply voltage as low as 0.4 V. The proposed circuit is based on the bulk-driven technique and use of cross-coupled self-cascode pairs that boosts the differential DC gain. The stability condition of this structure for the DC gain is considered by definition of two coefficients to cancel out a controllable percentage of the denominator. This expression for stability condition yield optimized value for the DC gain. Also, as the principle of operation of the proposed technique relies on matching conditions, Monte Carlo analyzes are considered to study of the behavior of the proposed circuit against mismatches. The designed P-OTA have a DC gain of 64 dB, 212 KHz unity gain bandwidth, 57phase margin that is loaded by 10 pF differential capacitive loads, while consume only 16 μW. Eventually, from the proposed P-OTA, a low-power Sample and Hold (S/H) circuit with sampling frequency of 10 KS/s has been designed and simulated. The correct functionality for this configuration is verified from –30℃ to 70℃. The simulated data presented is obtained using the HSPICE Environment and is valid for the 90 nm triple-well CMOS process.
This study characterizes the 19 kDa protein expressed by Mycobacterium avium subspecies paratuberculosis (MAP) as a glycolipoprotein, providing the foundation for future experiments regarding its antigenicity and role in disease pathogenicity. We have previously shown that a 4.8 kb insert from MAP will produce a 16 kDa recombinant protein when expressed in Escherichia coli and 19 kDa recombinant protein when expressed in M. smegmatis (smeg19K). The difference of 3 kDa in size of these expressed proteins may be related to post translational modifications that occur in Mycobacterium species. We hypothesized that smeg19K is a glycolipoprotein since BLAST analysis revealed approximately 76% amino acid identity between the MAP 19 kDa protein and a known lipoglycoprotein, the 19 kDa protein of M. tuberculosis. This prediction was confirmed by the following positive staining of smeg19K with Sudan Black 4B, a postelectrophoresis dye used to stain for lipids. Smeg19K has also stained positively for glycosylation with the lectin concavalin A, a highly specific stain for mannose residues. As expected, treatment with tunicamycin (an antibiotic known to inhibit N-glycosylation) and treatment with deglycosylation assay (non-specific for mannose), showed no reduction in size of 19 kDa glycolipoprotein.