The ever-increasing demands on wireless communications and sensing make RF filtering that suppresses strong out-of-band interference indispensable. In this talk, the concept of passive-mixer-first acoustic-filtering is discussed. The passive mixer frequency-translates a sharp but fixed-frequency acoustic-filtering response to a much higher and mixer-clock-defined tunable frequency. In addition, the usage of switched-LC impedance-aliasing-suppressing passive mixer preserves input matching, high linearity, and introduces minimal loss. Finally, design considerations associated with SAW/BAW filters, superheterodyne receiver architectures, and circuit implementations will be discussed and supported by two design examples and their measurement results.