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A compact differential voltage reference cell, which combines an original switched capacitor integrator with a digitally programmable bandgap core, is presented. The two-stage integrator maintains an always-valid output voltage while performing correlated double sampling to effectively reduce the effects of offset and flicker noise. Measurements performed on a prototype designed with the UMC 0.18...
Wireless communication systems and Ethernet networks call for moderate-resolution GS/s energy-efficient ADCs. While previous work [1] shows that the multi-bit per cycle SAR ADC can achieve low power due to various hardware reduction techniques, there are still a few limitations that restrain this architecture. First, the pre-charge slows down the logic and the DAC settling, especially during the MSB...
This paper presents a high linearity time-mode temperature sensor with close-loop architecture. The main loop utilizes a switched-capacitor equivalent resistor (Reqsc) to convert the linear values of ΔVBE and the output period of a Voltage-Controlled-Oscillator (VCO) into the control voltage of the VCO. A temperature independent equivalent resistor (Req) whose value only depends on clock period and...
Efforts to improve the resolution and power-efficiency of ADCs continue unabated, as is well documented in [2]. Although the number of new switched-capacitor (SC) ADC publications has declined over the years in favor of continuous-time designs, these circuits still remain attractive owing to their superior immunity to clock jitter and process variations. In this paper, we present three independent...
Thermoelectric generator (TEG) is a sensor that utilizes thermal gradients between cold plate and hot plate of the sensor and convert it into electricity. By having a concise and non-moving structure, the sensor attracts interest in studies to implement an autonomous self sustain system. Power generation of TEG is directly proportional to temperature gradient. Therefore, the device is dismissed when...
Most systems require a voltage reference independent of variation of power supply, process, or temperature, and a bandgap voltage reference (BGR) often serves this purpose. For ultra-low power (ULP) systems, the BGR may constitute a significant component of standby power, and the system start-up voltage is often determined by the voltage, Vin, at which the BGR becomes operational. Lowering Vin can...
Charge pump circuits are currently becoming a realistic alternative to the switching regulators in high voltage generation applications, especially in fully integrated circuit systems. This paper discusses several stabilization methods to improve voltage performance and robustness of integrated high voltage charge pumps. All the discussion and measurements are based on a monolithic integrated high...
This paper presents the design, simulation, bench measurement and long-term reliability test results of a drift-resistant clock generator. Designed for applications at a stable body temperature with a lifelong operating expectancy, this clock design uses multiple design techniques to minimize the long-term performance degradation and results in a clock circuit with superior frequency stability. This...
This paper proposes an interface circuit for wirelessly powered implants for mice temperature monitoring. The circuit contains the read-out circuit and a data converter. By using a novel approach to cancel the non-linear effects of thermistor sensors, the circuit achieves 27dB higher SFDR. The system is designed in UMC CMOS 0.18μm technology, which has 200KHz sampling rate, 8-bit resolution, and total...
This paper describes the design of a low power, energy-efficient CMOS smart temperature sensor intended for RFID temperature sensing. The BJT-based sensor employs an energy- efficient 2nd-order zoom ADC, which combines a coarse 5-bit SAR conversion with a fine 10-bit ΔΣ conversion. Moreover, a new integration scheme is proposed that halves the conversion time, while requiring no extra supply current...
This paper presents a bandgap reference capable of operating at supply voltages below 1V. In contrast to the vast majority of bandgap circuits the multiplication of the proportional to absolute temperature voltage is done by a switched capacitor network. Thus a reduced chip area is achieved. As a clock is needed for the switching, a relaxation oscillator is deeply integrated into the circuit. Combined...
A low power smart temperature sensor followed by an SC amplifier, buffer stage and a 12bit Successive-Approximation analogue-digital converter (ADC) for autonomous multi-sensor systems is presented. The proposed design is accurate within 0.1°C over the temperature range of −55°C to 125°C. A PTAT source like the one presented in [1] was used as a high accuracy temperature sensor. The read-out enables...
We describe a fully-adjustable dynamic range capacitance sensor circuit implemented with switched capacitors in a 3D process. The dynamic range and sampling frequency are set by the frequency of two clock inputs that control an on-chip four phase non-overlapping clock generation circuit. The chip also contains a bandgap reference, increasing the accuracy of the capacitance measurements. It also has...
Due to its restricted usage and accuracy in measuring extremely short interval of time, TDC (time to digital converter) embedded measurement devices are relatively expansive. Even if new applications are being developed in daily life as well as in industry, the cost condition of TDC based measurement systems needs to be improved. To reduce the deployment cost on a commercial scale, analogue interpolation...
A compact converter from capacitance to pulse width, suitable for interfacing integrated capacitive sensors is described. The circuit has been designed and fabricated using 0.32 mum/ 3.3 V CMOS devices from the BCD6s process of STMicroelectroncs and occupies an area of 1025 times 515 mum2. Measurements performed on the test chip showed an excellent linearity, a temperature drift of 300 ppm/degC, and...
A time-to-digital converter (TDC) capable to measure time intervals over a range of several microseconds with an accuracy of 100 - 200 ps has been designed. The TDC has been fabricated in a 1.2 um BiCMOS process and according to preliminary test results the single-shot resolution is better than 200 ps and the nonlinearity is less than 150 ps when input time intervals range from 2.5 to 2500 ns.
This paper reports of a micropower high precision MOS switched capacitor converter for a capacitive microtransducer. The converter has a digital output which is linearly related to the applied physical quantity and which is compatible with microprocessor systems. The principle of measurement used in this converter will be presented. The realized testchip and its performance will be described.
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