US Patent 7786769 On die signal detector without die power

In general, in one aspect, the disclosure describes an apparatus having on die circuitry coupled to at least one input port to receive a signal. A resistor is coupled to the on die circuitry and an off die power supply When a signal of sufficient amplitude is received by the on die circuitry the on die circuitry enables current to flow through the resister and reduces the voltage applied to the on die circuitry via the resister.