| Summary: | 碩士 === 國立中興大學 === 電機工程學系所 === 103 === According to the increasing demands for energy sources and losses of natural resources, green technology has become more and more important. In daily life, there are solar energy, thermal energy and vibration energy surrounding us, which can be stored into a battery as a supply source, by using an energy harvester and a converter.
The main problem for thermal energy conversion is that the converted voltage is too low for usual circuit to operate. Therefore, we have designed a low startup, two-stage DC-DC boost converter with negative voltage control which can improve the leakage problem of the native transistor. The two-stage design can improve the compatibility between the external capacitors and the whole circuit.
The boost converter is composed of a low-voltage clock generator, a negative voltage generator, a duty-cycle generator, a voltage detector, power MOS and some passive components. In the first stage, the low-voltage clock generator generates a signal to turn on the native transistor for boosting. Then, in the second stage, the negative voltage generator will shut the first stage down and the output signal of the voltage detector will switch on the threshold voltage control circuit for the second stage boosting operation.
This circuit is implemented with the TSMC 0.18um 1P6M process, with 300mV startup voltage and 1.5V output voltage with zero-load current; its peak conversion efficiency can reach 73% with 1mA load current. Furthermore, the minimum voltage for the circuit to start up is 180mV, which can boost to 1.2V with zero-load current.
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