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This paper presents a low power digital multiplier design by taking advantage of a 2-dimensional bypassing method. The proposed bypassing cells constituting the multiplier skip redundant signal transitions as well as computations when the horizontally partial product or the vertical operand is zero. Hence, it is a 2-dimensional bypassing method. Thorough post-layout simulations of a 8×8 digital multiplier using the proposed 2-dimensional bypassing method show that the power dissipation of the proposed design is reduced by more than 75% compared to prior designs. Physical measurements on silicon reveal that the proposed digital multiplier saves more than 28% even with pads' power dissipation compared to the prior works.

A mini-invasive system for long-term bladder urine pressure measurement system is presented. Not only is the design cost reduced, but also the reliability is enhanced by using a 1-atm canceling sensing instrumentation amplifier (IA). Because the urine pressure inside the bladder does not vary drastically, both the sleeping and working modes are required in order to save the battery power for long-term observation. The IA amplifies the signal sensed by the pressure sensor, which is then fed into the following analog-to-digital converter. Owing to the intrinsic 1-atm pressure existing inside the bladder, the IA must be able to cancel such a pressure from the signal picked up by the pressure sensor to keep the required linearity and the resolution for pressure measurement of the bladder urine. The pressure range of the proposed system is found out to be 14.7~19.7 Psi, which covers the range of all of the known unusual bladder syndromes or complications.

This study presents an implantable microcontroller-based bi-directional transmission system with an inductive link designed for biological signal sensing. The system comprises an external module and an implantable module. The external module incorporates a high-efficiency class-E transceiver with amplitude modulation scheme and a data recovery reader. The transceiver sends both power and commands to the implanted module, while the reader recovers the recorded biological signal data and transmits the data to a personal computer (PC) for further data processing. To reduce the effects of interference induced by the 2 MHz carrier signal, the implanted module uses two separate coils to perform the necessary two-way data transmission. The outward backward telemetry circuitry of the implanted module was based on the loadshift keying (LSK) technique. The transmitted sensed signal had a 10-bit resolution and a read-out rate of 115 kbps. The implanted module, measuring 4.5 x 3 x 1.2 cm3, was successfully verified in animal experiment in which the electroneurogram (ENG) signal was recorded from the sciatic nerve of New Zealand rabbits in response to nociceptive stimulation of foot. The reliable operating distance of the system was within about 3.5 cm with an efficiency of around 25%. Our present study confirms that the proposed biological signal sensing device is suitable for various implanted applications following an appropriate biocompatible packaging procedure.

The physical implementation of a prototypical 250-MHz CMOS 4-T SRAM is described in this paper. The proposed SRAM cell takes advantage of a negative word-line scheme to minimize the leakage current of the cell access transistors. As a result, the standby power consumption is drastically reduced. The proposed 4-kb 4-T SRAM is measured to consume 0.32 mW in the standby mode, and a 3.8-ns access time in the R/W mode. The highest operating clock rate is measured to be 263 MHz.Index Terms-Leakage current, negative word-line (NWL), power-delay product, SRAM, 4-T SRAM cell.