Amplifier with integrated filter

An apparatus comprising:

• an amplifier configured to receive an input signal and provide an output signal, the amplifier comprising:
• a gain stage including a transistor configured to receive the input signal at a gate and provide signal amplification for the input signal;
• a filter stage stacked and coupled to the gain stage between a supply voltage and circuit ground in a common integrated circuit and configured to provide notch filtering for the input signal and generate an output signal;
• and
• a buffer stage coupled between a load stage and the filter stage and configured to buffer a filtered signal from the filter stage.

A method comprising:

• amplifying an input signal with a gain stage including a transistor configured to receive the input signal at a gate to obtain an amplified signal;
• filtering the amplified signal with a filter stage stacked and coupled to the gain stage between a supply voltage and circuit ground in a common integrated circuit to generage an output signal, the gain stage and the filter stage being part of an amplifier with integrated filter;
• and
• buffering the filtered signal with a buffer stage coupled between a load stage and the filter stage to obtain a buffered signal, the buffer stage being part of the amplifier with integrated filter.

An apparatus comprising:

• means for amplifying an input signal with a gain stage including a transistor configured to receive the input signal at a gate to obtain an amplified signal;
• means for filtering the amplified signal with a filter stage stacked and coupled to the gain stage between a supply voltage and circuit ground in a common integrated circuit to generate an output signal, the gain stage and the filter stage being part of an amplifier with integrated filter;
• and
• means for buffering the filtered signal with a buffer stage coupled between a load stage and the filter stage to obtain a buffered signal, the means for buffering being part of the amplifier with integrated filter.