An improved common-mode feedback loop for the differential-difference amplifier

作者：Centurelli Francesco; Simonetti Andrea^*; Trifiletti Alessandro

来源：Analog Integrated Circuits and Signal Processing, 2013, 74(1): 33-48.

DOI：10.1007/s10470-012-9961-1

• Positive-feedback compensation
• Differential difference amplifier
• Common-mode feedback loop
• Sample-and-hold circuits

Unconditional stability of the high-gain amplifiers is a mandatory requirement for a reliable steady-state condition of time-discrete systems, especially for all blocks designed to sample-and-hold (S/H) circuits. Compared to differential path, the common-mode feedback loop is often affected by poles and zeros shifting that degrades the large signal response of the amplifiers. This drawback is made worse in some well-known topologies as the difference-differential amplifier (DDA) that shows non-constant transconductance and poor linearity. This work proposes a body-driven positive-feedback frequency compensation technique (BD-PFFC) to improve the linearity for precision DDA-based S/H applications. Theoretical calculations and circuit simulations carried out in a 0.13 mu m process are also given to demonstrate its validity.

• 出版日期2013-1