Comparator with noise cancellation for switching power converters

A circuit comprising:

• a comparator having a first comparator input, a second comparator input, and a comparator output, the comparator coupled to a supply terminal;
• first circuitry coupled to a boot terminal and to a switching terminal, the first circuitry configured to produce, at the first comparator input, a first voltage signal proportional to a difference between a boot voltage at the boot terminal and a switching voltage at the switching terminal, the first voltage signal including a first noise component;
• second circuitry coupled to the supply terminal and configured to produce, at the second comparator input, a second voltage signal;
• and
• noise cancellation circuitry coupled to the boot terminal, the switching terminal, and the second circuitry, the noise cancellation circuitry configured to introduce into the second voltage signal a second noise component substantially matching the first noise component;
• wherein the comparator is configured to produce, at the comparator output, an output signal that transitions from a first value to a second value responsive to the first voltage signal transgressing a threshold value based on the second voltage signal.

A buck converter comprising:

• a first transistor coupled between an input voltage terminal and a switching terminal;
• a second transistor coupled between the switching terminal and a ground terminal;
• a driver coupled to a boot terminal and the switching terminal, and having a driver output coupled to a control terminal of the first transistor, the driver configured to provide a drive signal at the control terminal of the first transistor;
• and
• a boot comparator system configured to monitor a boot voltage at the boot terminal, the boot comparator system including
• a comparator having a first comparator input, a second comparator input, and a comparator output, the comparator coupled to a supply terminal,
• a third transistor coupled between the boot terminal and the first comparator input, and having a control terminal coupled to the switching terminal,
• a fourth transistor coupled between the boot terminal and the second comparator input, and having a control terminal coupled to the switching terminal,
• a fifth transistor coupled between the supply terminal and the second comparator input, and
• a voltage reference generator coupled to the supply terminal and to a control terminal of the fifth transistor.