Steven L. Garverick

An Efficient BICS Design for SEUs Detection and Correction in Semiconductor Memories

We propose a new built-in current sensor (BICS) to detect single event upsets (SEUs) in SRAM. The BICS is designed and validated for 100 nm process technology. The BICS reliability analysis is provided for process, voltage and temperature variations, and power supply noise. The BICS detects various shapes of current pulses generated due to particle strike. The BICS power consumption and area overhead are also provided. The BICS is found to be very reliable for process, voltage and temperature variations and under stringent noise conditions.

Low-Power Wireless Micromanometer System for Acute and Chronic Bladder-Pressure Monitoring

This letter describes the design, fabrication, and testing of a wireless bladder-pressure-sensing system for chronic, point-of-care applications, such as urodynamics or closed-loop neuromodulation. The system consists of a miniature implantable device and an external RF receiver and wireless battery charger. The implant is small enough to be cystoscopically implanted within the bladder wall, where it is securely held and shielded from the urine stream. The implant consists of a custom application-specific integrated circuit (ASIC), a pressure transducer, a rechargeable battery, and wireless telemetry and recharging antennas. The ASIC includes instrumentation, wireless transmission, and power-management circuitry, and on an average draws less than 9 μA from the 3.6-V battery. The battery charge can be wirelessly replenished with daily 6-h recharge periods that can occur during the periods of sleep. Acute in vivo evaluation of the pressure-sensing system in canine models has demonstrated that the system can accurately capture lumen pressure from a submucosal implant location.

Microfabricated Shear Stress Sensors, Part 1: Design and Fabrication

The design and fabrication of shear stress sensors based on the floating-element method and polysilicon-surface-micromachining technology is reported. Three designs have been developed for microfabrication, two including monolithic integration of mechanical sensor elements with on-chip circuitry. The first design is four-mask standard polysilicon-surface-micromachining process to develop passive floating-element sensors with optically determined deflection sensitivity. The second-generation devices are fabricated in a six-mask modified N-channel metal-oxide-semiconductor process, where sensor elements and signal conditioning circuitry have been integrated on the sensor die for amplified voltage output. The third design modifies the commercially available micromachined by replacing the accelerometer element with a shear-stress-sensitive floating element, enabling active sensing for linear response and self-test features

A 32-channel charge readout IC for programmable, nonlinear quantization of multichannel detector data

A Charge Readout Integrated Circuit (CRIC) which converts detector charges to digital codes is described. The CRIC provides 32 channels of circuitry needed to form charge-to-digital converters having a total dynamic range of 17 b comprised of 4 b of pre-amp gain control and a conversion range of 13 b. Each channel includes a switched-capacitor integrator, a double-sampling amplifier, a sampling comparator, and a 12-b digital latch, forming a pipeline from which a new conversion result is readout every 50 /spl mu/s. The data conversion scheme implements a programmable compression curve, which is stored as a lookup table in an off-chip, digital memory. In addition to the lookup table, data conversion requires an off-chip digital-to-analog converter, both of which may be shared by any number of CRICs. The CRIC was fabricated using a 3-/spl mu/m, n-well BiCMOS process, and occupies a die area of 5.1 mm/spl times/7.5 mm. It operates at 10 MHz, consumes 440 mW from /spl plusmn/5-V supplies, and has a demonstrated input-referred noise performance of 2.2 /spl mu/V r.m.s., i.e., 1400 e/sup -/ on 100 pF of shunt capacitance. >

An oversampled capacitance-to-voltage converter IC with application to time-domain characterization of MEMS resonators

This paper reports the first electronic circuit used to measure the motion of a microelectromechanical systems (MEMS) resonator in the time domain. The measurement of the shuttle position is made using a capacitance-to-voltage converter IC that has been developed by combining correlated double sampling with delta modulation in a fully differential circuit topology. This oversampling circuit may be adjusted to trade bandwidth (sample rate) for resolution, while reference levels may be adjusted to set the desired sensitivity to accommodate a large range of capacitive sensor interface applications. The IC was fabricated using an inexpensive, 1.5-/spl mu/m, double-metal, double-polysilicon CMOS technology, and test results demonstrate a resolution of 170 aF for a signal bandwidth of 3 kHz, a 68-dB dynamic range, and nonlinearity less than 0.16%. The converter IC was used to characterize a comb-drive, SiC lateral MEMS resonator by time-domain measurement of its shuttle-comb capacitance. Resonant frequency was found to be 16.6 kHz, independent of operating pressure, but quality factor varied from 51 at 760-Torr pressure to 6900 at 175 mTorr. The ability to accurately characterize the SiC resonator shows that the packaging approach used in this study is sufficient to interface capacitive-based MEMS devices with Si ICs in cases where on-chip integration is not feasible or possible.

A miniature hybrid robot propelled by legs

Describes the development of an autonomous hybrid micro-robot that uses legs for propulsion and support of the rear half of the body and uses a pair of wheels for support of the front half. McKibben artificial muscles actuate the legs and the compressed air that activates the actuators is generated by an on-board power plant comprising a pair of lithium batteries powering a gear motor driven air compressor. The control is also onboard in the form of a PIC that controls the actuators through four three-way valves that each consists of a pair of MEMS devices.

Wireless, Ultra-Low-Power Implantable Sensor for Chronic Bladder Pressure Monitoring

The wireless implantable/intracavity micromanometer (WIMM) system was designed to fulfill the unmet need for a chronic bladder pressure sensing device in urological fields such as urodynamics for diagnosis and neuromodulation for bladder control. Neuromodulation in particular would benefit from a wireless bladder pressure sensor which could provide real-time pressure feedback to an implanted stimulator, resulting in greater bladder capacity while using less power. The WIMM uses custom integrated circuitry, a MEMS transducer, and a wireless antenna to transmit pressure telemetry at a rate of 10 Hz. Aggressive power management techniques yield an average current draw of 9 μA from a 3.6-Volt micro-battery, which minimizes the implant size. Automatic pressure offset cancellation circuits maximize the sensing dynamic range to account for drifting pressure offset due to environmental factors, and a custom telemetry protocol allows transmission with minimum overhead. Wireless operation of the WIMM has demonstrated that the external receiver can receive the telemetry packets, and the low power consumption allows for at least 24 hours of operation with a 4-hour wireless recharge session.

Fully-monolithic, 600°C differential amplifiers in 6H-SiC JFET IC technology

A family of fully-integrated differential amplifiers was designed and fabricated in 6H-SiC, n-channel JFET integrated-circuit technology. A single-stage amplifier with resistor loads has gain-bandwidth of ∼2.8 MHz, and differential-mode gain that varies by less than 1 dB from 25–600°C. A two-stage amplifier with current-source loads and common-mode feedback in 1^st-stage, and resistor loads in 2^nd-stage has gain-bandwidth of 1.4 MHz, and differential-mode gain of 69 dB at 576°C, with just 3.6 dB gain-variation from 25–576°C.

Wireless micromanometer system for chronic bladder pressure monitoring

This paper describes a wireless system to monitor urinary bladder pressure comprising an implantable device with an external receiver and wireless battery charger. The device is intended to be implanted within the bladder wall, sealed behind the urothelial lining. This location is protected from the urine stream, thus avoiding mineral encrustation and stone formation, and is suitable to measure intravesical pressure in chronic applications. The implant is dimensionally designed to gain access to the bladder using conventional urological tools, e.g. a cystoscope. The active circuit implant features a custom application-specific integrated circuit (ASIC), rechargeable battery and wireless telemetry. Inductive charging, novel power management schemes and innovative packaging allow this device to be inserted through the urethra, implanted within the bladder wall, and operate for a lifetime of up to 10 years.

Cricket-based robots

This article describes the development of an autonomous hybrid microrobot that uses legs for propulsion and support of the rear half of the body and a pair of wheels for support of the front half. McKibben artificial muscles actuate the legs, and compressed air is generated by an onboard power plant. Control is also onboard in the form of a PIC microcontroller, from Microchip Technology Inc., that controls the actuators through four three-way valves that are each made up of a pair of microelectromechanical system devices. Its motion resembles that of a cricket.