A Spread Spectrum Clock Generator With Nested Modulation Profile for a High-Resolution Display System

Abstract

A spread-spectrum clock generator is implemented using a nested modulation profile to reduce the peak power levels of radiated electro-magnetic emissions in display products. The display data interface is a potential source of interference, and the spread spectrum technique has been extensively used for display interfaces. The proposed nested profile can further reduce electro-magnetic interference without any degradation in the other characteristics. A test chip was fabricated using a 55-nm CMOS process, and the test results indicate a 41-dB reduction. The sensitivity of a wireless receiver to interference is tested, and the EVM results for the proposed nested profile exhibits an improvement of 1.4 dB compared to those of the triangular profile.