Protecting analog circuits with parameter biasing obfuscation

A methodology to secure analog intellectual property (IP) by obfuscating biasing conditions is presented in this paper. Previous research methodologies have focused on protecting digital IP from theft, overproduction, counterfeiting, and Trojan insertion. Analog IP has not been investigated as it does not share the same replicated structures and functionalities used for digital protection. The bias encryption techniques presented in this paper are implemented on a phase locked loop (PLL). The operating frequency of the PLL is masked in the range of 800 MHz to 2.2 GHz with a 40-bit encryption key. The probability of determining the correct key through brute force attack is 9.095×10
^-13
. The overheads of encrypting the PLL include a 6.3% increase in active area, a 0.89% increase in power consumption, and a 5 dBc/Hz increase in phase noise.