Write pulse generator for 16x DVD recording with symmetric CMOS inverter ring oscillator

This paper reports the design and measurement results of a write pulse generator IC for rewritable CD and DVD disk drives implemented in a standard digital 0.35 μm CMOS technology. The chip is the interface between a processor and a laser driver. It provides accurate timing signals to the laser driver via a four-level differential current interface. Transitions between current levels are programmable with 149 ps resolution at a data rate of 420 Mb/s, corresponding to 16x DVD write speed. The chip includes a digital core managing the different write strategies, a CMOS serial interface to the processor for programming, a low power, low phase noise, 64-phase ring voltage-controlled oscillator (VCO) based on CMOS Inverters, a phase-locked loop (PLL) locking the VCO to the system clock, and a current interface to the laser driver. The PLL phase noise is -144 dBc/Hz at 10 MHz offset from the 105 MHz carrier. At this frequency, the rms jitter is 1.1 ps with 0.8 mA VCO core supply current. The chip is fully ESD protected.