Method for controlling fast tracking power supply, fast tracking power supply, and system

A fast tracking power supply, comprising:

• a controllable voltage source that comprises a linear amplifier and a power supply voltage switching unit;
• a current detection unit;
• and
• a tracking current source, wherein:
• the linear amplifier is configured to receive a first control signal that is based on a reference signal, and to control a load voltage according to the received first control signal;
• the power supply voltage switching unit is configured to receive a second control signal based on the reference signal that is different from the first control signal, and to provide one of a plurality of discrete voltages as a voltage source for the linear amplifier according to the second control signal;
• the current detection unit is configured to detect an output current of the combined controllable voltage source, and to output a third control signal according to a detection result;
• and
• the tracking current source is configured to receive the third control signal output by the current detection unit, and adjust an output current of the tracking current source according to the third control signal, so as to implement low-frequency tracking of a load current,
• wherein the controllable voltage source is connected to the current detection unit in series and then connected to the tracking current source in parallel to provide a current.