Patent ID: 7616769

Claim:
An apparatus, comprising: a signal level limiting apparatus having a signal level attenuation circuit configured to receive a source electrical signal from a signal source that activates an attenuation network of the signal level attenuation circuit to attenuate the source electrical signal to generate an output electrical signal at an output in response to a signal level of the source electrical signal crossing a threshold; a threshold shifting circuit configured to shift the signal level threshold of the source electrical signal for activating the signal level attenuation circuit, the threshold shifting circuit having a control voltage source coupled to the attenuation network via a resistive element for applying a voltage to the attenuation network; wherein the threshold shifting circuit further includes a current steering circuit coupled to the shift control voltage source and coupled in parallel to the signal source; and wherein the current steering circuit includes a first diode, a first resistor, a second resistor, and a second diode coupled in series and wherein one terminal of the shift control voltage source is coupled between the first and second resistors.