Gain-adjustable amplifier circuit

An amplifier circuit comprising:

• an amplifier configured to generate an amplified input signal according to an input signal;
• and
• an attenuator circuit coupled to the amplifier, comprising:
• an input terminal for receiving the input signal or the amplified input signal;
• an output terminal;
• a reference voltage terminal;
• a zeroth resistor-switch circuit comprising:
• a first terminal;
• a second terminal, wherein the first terminal is coupled to the input terminal, and the second terminal is coupled to the output terminal;
• or the first terminal is coupled to the output terminal and the second terminal is coupled to the input terminal;
• a zeroth switch coupled between the first terminal of the zeroth resistor-switch circuit and the second terminal of the zeroth resistor-switch circuit;
• a zeroth resistor coupled between the first terminal of the zeroth resistor-switch circuit and the second terminal of the zeroth resistor-switch circuit;
• a first resistor coupled between the zeroth resistor and the second terminal of the zeroth resistor-switch circuit;
• and
• a first switch comprising:
• a first terminal coupled to the zeroth resistor and the first resistor;
• a second terminal coupled to the second terminal of the zeroth resistor-switch circuit;
• and
• a control terminal;
• a first resistor-switch circuit comprising:
• a first terminal;
• a second terminal, wherein the first terminal is coupled to the input terminal, and the second terminal is coupled to the reference voltage terminal;
• or the first terminal is coupled to the reference voltage terminal, and the second terminal is coupled to the input terminal;
• a zeroth resistor coupled between the first terminal of the first resistor-switch circuit and the second terminal of the first resistor-switch circuit;
• a first resistor coupled between the zeroth resistor and the second terminal of the first resistor-switch circuit;
• and
• a first switch comprising:
• a first terminal coupled to the zeroth resistor and the first resistor;
• a second terminal coupled to the second terminal of the first resistor-switch circuit;
• and
• a control terminal;
• and
• a second resistor-switch circuit comprising:
• a first terminal;
• a second terminal, wherein the first terminal is coupled to the output terminal, and the second terminal is coupled to the reference voltage terminal;
• or the first terminal is coupled to the reference voltage terminal, and the second terminal is coupled to the output terminal;
• a zeroth resistor coupled between the first terminal of the second resistor-switch circuit and the second terminal of the second resistor-switch circuit;
• a first resistor coupled between the zeroth resistor and the second terminal of the second resistor-switch circuit;
• and
• a first switch comprising:
• a first terminal coupled to the zeroth resistor and the first resistor;
• a second terminal coupled to the second terminal of the second resistor-switch circuit;
• and
• a control terminal.