Cryptography – Communication system using cryptography – Symmetric key cryptography
Reexamination Certificate
2006-06-27
2006-06-27
Vu, Kim (Department: 2134)
Cryptography
Communication system using cryptography
Symmetric key cryptography
C341S144000, C380S268000
Reexamination Certificate
active
07068788
ABSTRACT:
The present invention is related to digital to analog converter (DAC) input data encryption off-chip and decryption on-chip to suppress input data in-band harmonic leakage through package related parasitic capacitance. More specifically, the present invention relates to the method and apparatus of input data encryption off-chip by forming the logical exclusive-OR of the raw data and a random single bit data stream. The encrypted data is then read onto the DAC chip where the data is decrypted using identical circuitry and an identical random single bit data stream. The off-chip encryption isolates harmonic content within the input data, preventing leakage of input data harmonic content through IC package-related parasitic capacitance into DAC outputs. Any leakage appears as an increase in spectral noise rather than output distortion and as such, has a much smaller impact on DAC narrow band linearity.
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Haque Yusuf A.
Johnstone Kevin K.
McCarroll Benjamin J.
Heneghan Matthew
Maxim Integrated Products Inc.
Perkins Coie LLP
Vu Kim
LandOfFree
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