Methods and circuits for generating a high voltage and related semiconductor memory devices

A method of generating a high voltage for programming a non-volatile memory device, comprising:

• generating a first ramping voltage having a first ramping speed;
• outputting the first ramping voltage until the first ramping voltage reaches a predetermined level;
• generating a second ramping voltage having reduced ripple compared to the first ramping voltage;
• and
• outputting the second ramping voltage when the first ramping voltage reaches the predetermined level.

A high voltage generating circuit, comprising:

• a high voltage generating unit configured to generate an initial voltage having a first ramping speed;
• a ramping circuit configured to generate a first ramping voltage in response to the initial voltage, the first ramping voltage having a second ramping speed slower than the first ramping speed;
• and
• a voltage controlling unit responsive to the ramping circuit and configured to generate a second ramping voltage having a third ramping speed slower than the second ramping speed, and to output the first ramping voltage or the second ramping voltage responsive to a voltage level of the first ramping voltage.

A program voltage generating circuit, comprising:

• a pumping circuit configured to generate an initial voltage signal;
• a first voltage regulator coupled to the pumping circuit and configured to control a voltage level of the initial voltage signal;
• a ramping circuit coupled to the pumping circuit and configured to generate a first ramping voltage in response to the initial voltage signal;
• and
• a second voltage regulator coupled to the ramping circuit and configured to generate a second ramping voltage having a reduced ripple compared to a ripple of the first ramping voltage.