Amplifier circuit having adjustable gain

An amplifier circuit having an adjustable gain, comprising:

• an input terminal used for receiving an input signal;
• an output terminal used for outputting an output signal;
• an amplifier including:
• an input terminal receiving the input signal through the input terminal of the amplifier circuit;
• and
• an output terminal used for outputting the input signal that is amplified;
• and
• an attenuation circuit including:
• an input terminal;
• and
• an output terminal;
• wherein:
• the input terminal of the attenuation circuit is coupled to the output terminal of the amplifier, and the output terminal of the attenuation circuit is coupled to the output terminal of the amplifier circuit, so as to provide a plurality of attenuations to the input signal that is amplified, and generate a first attenuation signal;
• or wherein the input terminal of the attenuation circuit is coupled to the input terminal of the amplifier circuit, and the output terminal of the attenuation circuit is coupled to the output terminal of the amplifier circuit, so as to provide the plurality of attenuations to the input signal, and generate a second attenuation signal;
• the attenuation circuit includes a plurality of attenuation units, and each of the plurality of attenuation units is used for providing one of the plurality of attenuations;
• and
• one of the plurality of attenuation units is used for providing the attenuation of 0 dB out of the plurality of attenuations.

An amplifier circuit having an adjustable gain, comprising:

• an input terminal used for receiving an input signal;
• an output terminal used for outputting an output signal;
• an amplifier including:
• an input terminal receiving the input signal through the input terminal of the amplifier circuit;
• and
• an output terminal used for outputting the input signal that is amplified;
• and
• an attenuation circuit including:
• an input terminal;
• and
• an output terminal;
• wherein:
• the input terminal of the attenuation circuit is coupled to the output terminal of the amplifier, and the output terminal of the attenuation circuit is coupled to the output terminal of the amplifier circuit, so as to provide a plurality of attenuations to the input signal that is amplified, and generate a first attenuation signal;
• or wherein the input terminal of the attenuation circuit is coupled to the input terminal of the amplifier circuit, and the output terminal of the attenuation circuit is coupled to the output terminal of the amplifier circuit, so as to provide the plurality of attenuations to the input signal, and generate a second attenuation signal;
• the attenuation circuit includes a plurality of attenuation units, and each of the plurality of attenuation units is used for providing one of the plurality of attenuations;
• one of the plurality of attenuation units includes a first switch, a first terminal of the first switch is coupled to the input terminal of the attenuation circuit, a second terminal of the first switch is coupled to the output terminal of the attenuation circuit, and a control terminal of the first switch is used for receiving a first control signal;
• another one of the plurality of attenuation units includes a first x-type attenuator used for providing a first attenuation of the plurality of attenuations, and the first x-type attenuator includes:
• a second switch, wherein a first terminal of the second switch is coupled to the input terminal of the attenuation circuit, a second terminal of the second switch is coupled to a reference potential terminal, and a control terminal of the second switch is used for receiving a second control signal;
• a third switch, wherein a first terminal of the third switch is coupled to the output terminal of the attenuation circuit, a second terminal of the third switch is coupled to the reference potential terminal, and a control terminal of the third switch is used for receiving the second control signal;
• a fourth switch, wherein a first terminal of the fourth switch is coupled to the input terminal of the attenuation circuit, a second terminal of the fourth switch is coupled to the output terminal of the attenuation circuit, and a control terminal of the fourth switch is used for receiving the second control signal;
• a first resistor, wherein a first terminal of the first resistor is coupled to the input terminal of the attenuation circuit and a second terminal of the first resistor is coupled to the first terminal of the second switch, or the first terminal of the first resistor is coupled to the second terminal of the second switch and the second terminal of the first resistor is coupled to the reference potential terminal;
• a second resistor, wherein a first terminal of the second resistor is coupled to the output terminal of the attenuation circuit and a second terminal of the second resistor is coupled to the first terminal of the third switch, or the first terminal of the second resistor is coupled to the second terminal of the third switch and the second terminal of the second resistor is coupled to the reference potential terminal;
• and
• a third resistor, wherein a first terminal of the third resistor is coupled to the input terminal of the attenuation circuit and a second terminal of the third resistor is coupled to the first terminal of the fourth switch, or the first terminal of the third resistor is coupled to the second terminal of the fourth switch and the second terminal of the third resistor is coupled to the output terminal of the attenuation circuit.