A reconfigurable differential-to-single-ended autonomous current adaptation buffer amplifier (ACABA) suitable for biomedical applications is proposed. The ACABA, based on floating-gate technologies, is a capacitive circuit, of which output DC level and bandwidth can be adjusted by programming charges on floating nodes. The gain is variable by switching different amounts of capacitors without altering the output DC level. Without extra sensing and control circuitries, the current consumption of the proposed ACABA increases spontaneously when the input signal is fast or large, achieving a high slew rate. The supply current dwindles back to the low quiescent level autonomously when the output voltage reaches equilibrium. Therefore, the proposed ACABA is power-efficient and suitable for processing physiological signals. A prototype ACABA has been designed and fabricated in a 0.35μm CMOS process occupying an area of 0.151 mm2. When loaded by a 10 pF capacitor, it consumes 3 μW to achieve a unity-gain bandwidth of 100 kHz with a measured IIP2 value of 52.66 dBV and a slew rate of 7.86 V/μs.