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Power Supplies
Published in Douglas Self, Small Signal Audio Design, 2020
It is of course also possible to make a ±17 V supply by using variable output voltage IC regulators such as the LM317/337. These maintain a small voltage (usually 1.2 V) between the OUTPUT and ADJ (shown in figures as GND) pins and are used with a resistor divider to set the output voltage. The quiescent current flowing out of the ADJ pin is a couple of orders of magnitude lower than for the 78/79 series, at around 55 μA, and so a simple resistor divider gives adequate accuracy of the output voltage, and transistors are no longer needed to absorb the quiescent current. A disadvantage is that this more sophisticated kind of regulator is somewhat more expensive than the 78/79 series; at the time of writing they cost something like 50% more. The 78/79 series with transistor voltage-setting remains the most cost-effective way to make a non-standard-voltage power supply at present.
Testing of Integrated Circuits
Published in Jerry C. Whitaker, Microelectronics, 2018
To implement voltage based testing or any of the other types of tests, initialization of the circuit must take place, and control and observation of the internal nodes must occur. The following are four basic categories of tests: External stored response testing. This is the most common form for today’s integrated circuits and it relies heavily on large IC automated test equipment (ATE).Builtin-self-test (BIST). This is method of defining and building test circuity onto the integrated circuit. This technique provides stimulus patterns and observes the logical output of the integrated circuit.Scan testing. Some or all of the sequential elements are converted into a shift register for control and observation purposes.Parametric tests. The values of circuit parameters are directly measured. This includes the IDDQ test, which is good at detecting certain classes of defects. To implement an IDDQ test, a CMOS integrated circuit clock is stopped and the quiescent current is measured. All active circuitry must be placed in a low-current state, including all analog circuitry.
Vibration Energy Harvesting System
Published in Yen Kheng Tan, Energy Harvesting Autonomous Sensor Systems, 2017
Due to several design constraints imposed on the impact-based VEH system like miniature size, simple design, and low-cost requirements, a simple voltage regulator is used. According to Dewan et al. [112], if the voltage difference between the input and output of the linear voltage regulator is kept to a minimum, then the linear regulator’s efficiency is maximized. This is because a small amount of voltage is dropped across the voltage regulator; hence, little energy is wasted. A switched-mode voltage regulator, on the other hand, suffers from ripples in the output voltage due to its switching rates and has a very high quiescent current compared to a linear voltage regulator, especially in low-power operations where load currents are very low, on the order of microamperes. Although a switch-mode voltage regulator is relatively more complex, it has some superior advantages over a linear regulator, like high power conversion efficiency, voltage step-up and step-down capability, and more. After considering both the advantages and the disadvantages of applying the two types of voltage regulators for research, a linear regulator is more suitable for this VEH research work.
Parallel Processing Algorithms of Ultrasound Images
Published in IETE Journal of Research, 2021
As shown in Table 3, In general, the GPU implementation speed is 60 times faster than the CPU single-threaded speed. The step of extracting key points with a single CPU thread takes only a few hundred seconds, but the step of matching key points takes several hours, which is unacceptable in actual use. Similarly, it takes hours or even days to use the CPU single thread in the DVC calculation process, and the slower calculation speed is difficult to apply in practice. At this time, because the voltage difference between the input and output is small, the general linear voltage regulator chip cannot realize the voltage conversion. Therefore, this system uses the low dropout linear voltage regulator (LDO) chip RT9193 with low quiescent current consumption and high ripple rejection ratio and current limit protection to realize the 3.3 V voltage regulation function. Since its output current during normal operation is less than 300 mA, it can achieve high conversion efficiency.