A time-delay technique to improve GBW on negative feedback amplifiers

This paper presents a new method to improve the GBW (gain-bandwidth product) on negative feedback amplifiers. The proposed method is based on the introduction of time delay elements in the feedback loop, which can be exploited to retrieve significant bandwidth enhancements. This delayed feedback concept is analyzed, and considerations are presented for first order amplifiers, based on theoretical analysis. The concept is simulated and further demonstrated in a practical example using a series-shunt feedback amplifier with a TL081 operational amplifier (OA) and a 36m long coaxial cable as delay element. Measured experimental results show a maximum bandwidth improvement of almost 90%, from a theoretical maximum of 141%.