A unity-gain buffer capable of high slew rates in both the positive and negative directions is presented. By sensing the drain current of the common-drain device in an NMOS source follower, the extent of slewing is detected, and the tail current of the source follower is dynamically adjusted. A buffer incorporating this strategy was implemented in a 2 /spl mu/m p-well process. This buffer has over 4 times the negative-going slew rate and twice the bandwidth of a source follower, while requiring only 13% more static power. Moreover, the output voltage swing range is as large as that of a source follower. With a 20 pF output load, the measured 3-dB bandwidth was 9 MHz. The signal-to-total-harmonic-distortion ratio with 2 V/sub p-p/ sinewave input at a frequency of 2 MHz was better than 50 dB. >