Methods and apparatus to improve transient response performance of buck regulators

A buck regulator circuit comprising:

• controller circuitry;
• a high side field-effect transistor having a gate coupled to the controller circuitry, a drain configured to receive an input voltage, and a source coupled to a switch terminal;
• a low side field-effect transistor having a gate coupled to the controller circuitry, a drain coupled to the switch terminal, and a source coupled to ground;
• an inductor coupled to the switch terminal and configured to provide an output voltage;
• ramp emulator circuitry coupled to the switch terminal, a current sense positive (CSP) terminal, and a current sense negative (CSN) terminal, the ramp emulator circuitry configured to produce a first voltage on the CSP terminal and a second voltage on the CSN terminal;
• and
• comparator circuitry coupled to the CSP terminal and the CSN terminal, the comparator circuitry configured to provide a comparison of the first voltage and the second voltage to the controller circuitry, the comparison to form a closed loop within the buck regulator circuit, wherein a gain crossover frequency of the closed loop is independent of both the input voltage and the output voltage.

A system comprising:

• a supply unit configured to provide an input voltage;
• a buck regulator circuit including:
• controller circuitry;
• a high side field-effect transistor having a gate coupled to the controller circuitry, a drain configured to receive the input voltage, and a source coupled to a switch terminal;
• a low side field-effect transistor having a gate coupled to the controller circuitry, a drain coupled to the switch terminal, and a source coupled to ground;
• an inductor coupled to the switch terminal and configured to provide an output voltage;
• ramp emulator circuitry coupled to the switch terminal, a current sense positive (CSP) terminal, and a current sense negative (CSN) terminal, the ramp emulator circuitry configured to produce a first voltage on the CSP terminal and a second voltage on the CSN terminal;
• and
• comparator circuitry coupled to the CSP terminal and the CSN terminal, the comparator circuitry configured to provide a comparison of the first voltage and the second voltage to the controller circuitry, the comparison to form a closed loop within the buck regulator circuit, wherein a gain crossover frequency of the closed loop is independent of both the input voltage and the output voltage;
• and
• a load coupled to the inductor and configured to perform operations based on the output voltage.