Design Procedures for Three-Stage CMOS OTAs With Nested-Miller Compensation

Design procedures for three-stage CMOS operational transconductance amplifiers employing nested-Miller frequency compensation are presented in this paper. After describing the basic methodology on a Class-A topology, some modifications, to increase swing, slew-rate and current drive capability, are subsequently discussed for a Class-AB solution. The approaches developed are simple as they do not introduce unnecessary circuit constraints and yield accurate results. They are hence suited for a pencil-and-paper design, but can be easily integrated into an analog knowledge-based computer-aided design tool. Experimental prototypes, designed in a 0.35-mum technology by following the proposed procedures, were fabricated and tested. Measurement results were found in close agreement with the target specifications     

Improved Reversed Nested Miller Frequency Compensation Technique With Voltage Buffer and Resistor

This brief introduces and develops a novel frequency compensation technique for three-stage operational transconductance amplifiers. The new compensation topology exploits a voltage buffer and a nulling resistor to achieve a double pole-zero cancellation, occurring beyond the gain-bandwidth product. To verify the effectiveness of the compensation scheme, an amplifier has been fabricated in a standard 0.5-mum CMOS process. Experimental measurements are found to be in good agreement with the theoretical analysis and show an improvement in small-signal and large-signal performances     

Insurance coverage and residents' experience in a pediatric teaching clinic

To examine the relationship between insurance coverage and the diagnostic content of residents' experience in a hospital-based pediatric teaching clinic, we analyzed outpatient problem lists for 6543 patients seen in our clinic over a 15-month period. Problem-list contents were categorized using diagnostic clusters. The frequency distribution of clustered problems was compared for patients with four types of insurance coverage: indemnity insurance, health maintenance organization, Medicaid, and no insurance. The four insurance categories differed in the overall distribution of problems, but the differences could not be attributed to a disparity in the frequency of any single diagnosis or diagnostic cluster. We conclude that there was no important effect of insurance coverage on the diagnostic content of residents' experience in a teaching clinic.     

Potential for an external vaginal antiitch cream containing benzocaine to cause methemoglobinemia in healthy women

OBJECTIVES: Our purpose was to assess the potential for an external vaginal antiitch cream (20% benzocaine, 3% resorcinol) to significantly increase levels of methemoglobin above normal in healthy women. STUDY DESIGN: Fifty-five women reporting external vaginal itch were recruited for the study. Each patient was used as her own control with methemoglobin levels being measured before and after use of the cream. Women were instructed to apply a 1-inch strip of cream by fingertip to the external genital area three or four times a day for 7 consecutive days. RESULTS: There were no significant differences in methemoglobin levels before and after use or in levels from a subgroup of women aged > 50 years compared with levels in a younger population. CONCLUSIONS: This preparation appears to be safe when used as directed; however, the results cannot be extrapolated to the very young. Nevertheless, lavish or frequent application over wide areas of excoriation might lead to toxic concentrations and methemoglobinemia. Therefore patients with serious vaginal disease should be advised against self-treatment beyond the 7-day limit imposed by the Food and Drug Administration for over-the-counter external analgesic medications.     

Cyclophosphamide in the treatment of idiopathic nephrotic syndrome

Fifty-three patients 3 1/2 to 20 years of age with steroid-dependent idiopathic nephrotic syndrome (INS) were treated with cyclophosphamide and prednisone. Two dosage schedules were used: a short course (SC) at 3 to 5 mg/kg/day for six to eight weeks and a longer course (LC) at 3 to 5 mg/kg/day for eight weeks followed by 1.5 to 2.5 mg/kg for an additional four weeks. Prednisone was administered concurrently at 50 to 75 mg/sq M every other day. Twenty-nine patients were in the SC group and 24 in the LC group. The two groups did not differ significantly as to age at onset of idiopathic nephrosis nor as to the duration of the INS prior to cyclophosphamide therapy. All patients were followed for a minimum of 42 months after cyclophosphamide therapy. The SC was associated with a higher relapse rate during the first year than the LC (42% and 8% respectively, .01 larger than P less than .025). At 42 months 63% of the LC group were in remission compared with 21% in the SC group.     

The kinetics of gas transport in halide-activated aluminizing packs

The kinetics of diffusion of gaseous halides in an aluminizing pack are analyzed assuming the presence of an activator, as well as an aluminum-depleted zone. The influence of activator concentration on the aluminum transport rate is calculated for a wide range of activator concentrations in an AlF₃-activated pack. Theoretical results are compared with experimental data for the aluminization of nickel.     

A 2.5-GHz DDFS-PLL With 1.8-MHz Bandwidth in 0.35-$mu$m CMOS

A wideband frequency synthesizer architecture is presented. The proposed topology employs a direct digital frequency synthesizer (DDFS) to control the output frequency of an offset-PLL. In this way, the synthesizer features a very fine frequency resolution, 24 Hz, as in delta-sigma fractional-N PLLs, but without being affected by the quantization-induced phase noise. This, in turn, allows enlarging the loop bandwidth. The frequency synthesizer is designed to be employed as a direct modulator for Bluetooth transmitter in a low-cost 0.35-mum CMOS technology. At 2.5GHz it achieves 1.8-MHz bandwidth, while the settling time within 30ppm for an 80-MHz step is 3 mus. The integrated phase noise gives less than 1 degree of rms phase error and the worst-case spur is 48dBc at 1 MHz, well below the specifications. Power dissipation is 120 mW for the PLL core, 50 mW for the DDFS plus DACs, and 19 mW for the GFSK modulator.