Squelch circuit with adjustable reference level

A squelch circuit with an adjustable reference level, the squelch circuit comprising:

• an input level comparator, having a first, a second, a third and a fourth current input terminal, a first and a second input terminal, and an output terminal, wherein input signals for the first and the second input terminals are inverted;
• a first current source, coupled between the first current input terminal and an operation voltage;
• a second current source, coupled between the second current input terminal and the operation voltage;
• a third current source, coupled between the third current input terminal and a ground terminal;
• a fourth current source, coupled between the fourth current input terminal and the ground terminal;
• and
• a bias generator, coupled to input terminals of the first, second, third and fourth current sources to generate current bias signals to each of the first, second, third and fourth current sources, so that the first, second, third and fourth current sources generate the current, which adjusts the reference level.