A single-branch third-order low-pass filter with an ultracompact die size and extensive bandwidth (BW)-power scalability is described. It unifies a source follower, a stackable floating active inductor, and a feedforward capacitor to constitute a transistorized-LC-ladder topology with a stable pole-zero transfer function over a wide range of tunable BW. Differentially, only eight transistors and five untuned capacitors are required. Fabricated in 0.18-μm CMOS, the prototype occupies 0.014-mm die size. By scaling the bias current (and, hence, the power), the flexible BW measures 0.8 kHz at 1.25 nW and 0.94 GHz at 3.99 mW.