Abstract
In this paper, we present a regulated charge pump with extremely low output ripple (<1 mV) that can be used for accurate programming of nonvolatile memory. We present a technique to include a low-drop-out regulator inside the charge-pump regulation loop to reduce the ripple. This charge pump was fabricated in a 0.35 μ m standard CMOS process. The die area of this charge pump is 0.163 mm 2 . While operating from a 2.5 V supply, this charge pump generates regulated voltages up to 10 V.
Highlights
Charge-pump (CP) circuits are used to multiply the supply voltage (Vdd ) to generate a high-voltageDC output
We present a method to reduce output ripple in high-voltage charge pumps by adding a high power-supply-rejection ratio (PSRR) low-drop-out regulator (LDO) inside the regulation loop of the charge pump
This load capacitance is small enough that it can be integrated on-chip, and even larger integrated capacitances could be used to further reduce the ripple. These results show the effectiveness of the charge-pump-LDO loop combination; even the relatively low output ripple of the variable-frequency charge pump of [5] would have required
Summary
Charge-pump (CP) circuits are used to multiply the supply voltage (Vdd ) to generate a high-voltage. Since charge pumps use switched-capacitor techniques to generate elevated voltages, the output of the charge pumps typically have significant ripple. In [5], we presented a high-voltage charge pump that was able to achieve relatively low output ripple by using a variable-frequency regulation technique. We extend our previous results in [5] to achieve extremely low ripple in the output voltage. We present a method to reduce output ripple in high-voltage charge pumps by adding a high power-supply-rejection ratio (PSRR) low-drop-out regulator (LDO) inside the regulation loop of the charge pump. In [6], we presented early results of such a circuit, and here we present an improved version that has significantly better line/load regulation and a more detailed stability analysis.
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