This brief proposes a wideband interdigital bandpass filter (IBPF), exploiting the through-silicon via (TSV)-based 3-D integrated circuit (3-D IC) technology. IBPF is a structure composed of multiple groups of parallel-coupled line resonators, which can increase the bandwidth and out-band suppression (OBS) characteristics of a bandpass filter. Through the transformation of the Chebyshev low-pass circuit model, a seventh-order IBPF centered at 85 GHz is obtained. By combining TSV technology with the coupling coefficient method, the design process from the Chebyshev low-pass circuit model to the final optimization of IBPF is given. The fractional bandwidth (FBW) of IBPF based on TSV is 63%, the out-of-band suppression is greater than 80 dB, the insertion loss is 1.3 dB, the return loss is 20 dB, and the size of the compact IBPF is only <inline-formula> <tex-math notation="LaTeX">$0.50\times0.34$ </tex-math></inline-formula> mm<sup>2</sup> (<inline-formula> <tex-math notation="LaTeX">$0.48\times 0.33\,\,\lambda \text{g}^{2}$ </tex-math></inline-formula>).