A 11-bit Track and Hold Amplifier in 0.25 µm SiGe BiCMOS for RF sampling receivers

The paper describes a Track and Hold Amplifier (THA) suitable for RF sampling and Software Defined Radio receivers where high speed and high resolution are required. The reported THA is based on two main techniques: one for minimizing the differential droop rate and one for improving the HD3 in track mode. Measurements results show that the adopted solutions are both effective. In the desired input band around 1GHz, at the desired sub-sampling frequency (0.5GS/s) the THA provides a linearity compatible with 12-bit (Spurious Free Dynamic Range, SFDR). Moreover at the maximum achievable sampling frequency (1.5GS/s) the performances are quite constant and the resolution is compatible with 11-bit (SFDR) up to an input frequency of 1GHz.