In this paper, systematic design of a fully differential Gain-Boosted telescopic amplifier is presented. The main amplifier uses two separate Folded-Telescopic amplifiers to boost the gain. Limited output voltage swing is overcome through the use of second-stage Adaptive Biasing (AB) amplifiers with high current drive capability. The complete Gain-Boosted amplifier is used in a Differential Bottom-Plate Sample and Hold (SH) circuit where a Bootstrap circuit is employed on the sampling switches to overcome the voltage headroom limitations. The complete design is implemented in IBM 1.2V 0.13-$\mu m$ technology. Simulations show that the Gain-Boosted amplifier achieves 108dB of gain with only 0.5mW of power consumption. The SH circuit can operate at 1 Mega Samples (MS) per second for input signal amplitudes of 500mV.