Isolated communications lane demodulator

An apparatus, comprising:

• an envelope detector having first differential inputs, second differential inputs, and a detector output, the envelope detector including:
• a first transistor having a first control terminal, a first current terminal, and a second current terminal;
• a second transistor having a second control terminal, a third current terminal, and a fourth current terminal, in which the third current terminal is coupled to the first current terminal, the fourth current terminal is coupled to the second current terminal, and the first and second control terminals coupled to the first differential inputs;
• a first filter coupled between the first current terminal and a first supply voltage terminal;
• a third transistor having a third control terminal, a fifth current terminal, and a sixth current terminal;
• a fourth transistor having a fourth control terminal, a seventh current terminal, and an eighth current terminal, in which the seventh current terminal is coupled to the fifth current terminal, and the eighth current terminal is coupled to the sixth current terminal, and the third and fourth control terminals coupled to the second differential inputs;
• a second filter coupled between the fifth current terminal and the first supply voltage terminal;
• a current source coupled to a second supply voltage terminal;
• a resistor coupled between second and fourth current terminals and the current source;
• and
• a comparator having a first input, a second input and an output, in which the first input is coupled to the first current terminal, the second input is coupled to the fifth current terminal, and the output of the comparator coupled to the detector output.