In this paper, a Dickson charge pump circuit driven by boosted clock for low-voltage flash memories is proposed. Voltage pumping gain of each stage can be considerably improved by using high-voltage clock instead of using conventional clock. Since the voltage gain of each stage can be considerably increased by using this method, it can generate a high output voltage although the body effect still exists. Simulation results show that it can generate enough voltage to apply to the flash memory even at a supply voltage less than 1.5V. Because this method can be applied to almost all types of the improved Dickson charge pump circuits, it is expected that this method will improve the performance of the high voltage generating circuits for low-voltage flash memories.
Since a switched-capacitor sample-and-hold amplifier (SHA) has a feedback loop outside its op-amp, an op-amp with positive
feedback technique (PFT) can be adopted to enhance the DC-gain of the op-amp. This paper proposes a positive feedback amplifier with dramatically increased DC-gain of 127-dB and reports that a SHA adopting proposed amplifier is stable by feedback operation.
Measurement results demonstrated stable operation with spurious free dynamic range (SFDR) of 70-dB.