Bipolar differential cell with improved bandwidth performance

In this paper we present a novel technique to implement a differential cell with extended bandwidth. The solution exploits an auxiliary differential amplifier used in unity closed-loop gain, which regenerates the input signal, thereby allowing the reduction of the input capacitance of the main differential cell. Compared to a conventional topology with the same DC gain, the proposed one allows a maximum bandwidth improvement of a factor of two. Simulations using a SiGe bipolar technology in excellent agreement with expected results are also given.