Analog front-end circuit capable of dynamically adjusting gain

An analog front-end circuit capable of dynamically adjusting gain, adapted to receive an input signal from a signal source, the analog front-end circuit comprising:

• a programmable gain amplifier circuit, including:
• an amplifier configured to receive and amplify the input signal;
• a gain coarse adjustment circuit connected to the amplifier and configured to be controlled by a coarse control signal to adjust a gain of the programmable gain amplifier circuit in a coarse step according to an initial gain determined in a handshake mode;
• and
• a gain fine adjustment circuit connected to the amplifier and configured to be controlled by a fine control signal in a data mode after the handshake mode is ended, and adjust the gain of the programmable gain amplifier circuit in a fine step;
• at least one sensor configured to respectively perform sensing in the data mode to generate a sensing signal;
• a calculation circuit connected to the at least one sensor and configured to calculate a primary gain adjustment according to the initial gain, and calculate a secondary gain adjustment according to the sensing signal;
• a gain coarse control circuit configured to generate the coarse control signal according to the primary gain adjustment;
• and
• a gain fine control circuit configured to generate the fine control signal according to the secondary gain adjustment,
• wherein the coarse step is within a coarse adjustment range, the fine step is within a fine adjustment range, and the coarse adjustment range is larger than the fine adjustment range.