A 7 mW 2.5 GHz spread spectrum clock generator using switch-controlled injection-locked oscillator

As electric components are integrated in the smaller area, the electromagnetic interference (EMI) becomes a serious problem. To reduce an EMI problem and increase noise immunity of electric circuit, the clock spreading is one of the most popular methods these days. This work proposes a switch-controlled injection-locked oscillator (SCILO)-based spread spectrum clock generator (SSCG) with the features including low power consumption, simple operation mechanism, and small core area. In addition, sub-harmonic injection locking is used to provide high frequency output signal. The test-chip fabricated in 0.13 μm CMOS technology provides 2.5 GHz output clock with 1 % spreading ratio. Peak reduction is 13.5 dB at 1 % spreading ratio. The proposed SSCG consumes 7 mW from 1.2 V supply and only occupies 0.034 mm².