Abstract: A method for protecting analog or mixed signal ICIP uses adjustment requirements of analog circuits to provide an obfuscated mechanism for preventing unauthorized use of an analog or mixed-signal IC (“AIC”) by disabling the AIC until application of an adjustment signal that is within a narrow enabling subrange. Embodiments significantly increase the adjustment range beyond the enabling subrange, and/or omit AIC tuning outputs that are not required for operation of the IC. Embodiments include “clipping” circuits that render the AIC outputs unresponsive to tuning signals outside of the enabling subrange. Information regarding the enabling subrange and/or a separate enabling IC can be provided to authorized users, and/or enabling bits of a digital adjustment input can be permanently set by the ICIP owner after AIC manufacture. The ICIP can be further protected by a security feature that can be unique to each AIC, and/or by using a two-foundry production method.