We present the design, architecture and experimental results of the low jitter Clock and Data Recovery (CDR) and Phase Locked Loop (PLL) circuit in the Low-Power Gigabit Transceiver (lpGBT) ASIC. This circuit includes a low noise radiation-tolerant integrated LC-oscillator with a nominal frequency of 5.12 GHz to support a 10.24 Gbps uplink and a 2.56 Gbps downlink CDR. This CDR employs a novel loop architecture with a high-speed feed forward loop stabilization technique. A test circuit was fabricated in a 65 nm CMOS technology and has been tested experimentally for correct operation in the foreseen radiation environment.