The TQ8103 is a monolithic clock and data recovery (CDR) IC that receives NRZ data, extracts the high-speed clock, and presents the separated data and clock as its outputs. This device is designed specifically for SONET OC-12 and SDH STM-4 applications at 622 Mb/s. Its on-chip phase-locked loop (PLL) generates a stable 622.08 Mb/s reference based upon an external 38.88 MHz TTL reference. The PLL is based on a VCO constructed from integrated reactive components, which form a low-jitter, high-Q differential tank circuit. Both frequency- and phase-detect circuits reliably acquire and hold lock in worst-case SONET jitter conditions and scrambling patterns. The lock-detect circuitry signals when the CDR acquires frequency lock.