Miniaturized Low-Pass Filter Using IPD Technology for Cryogenic Quantum Applications

This paper presents miniature low-pass filters (LPF) using Integrated Passive Device technology for cryogenic quantum computing applications. These are crucial for providing a clean DC bias in qubit control and readout. Based on a 5<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sup>-order elliptic filter, we propose two LPF designs. One has a cascade topology <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\text{LPF}_{\mathrm{I}})$</tex>, and the other incorporates extra resistors <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\text{LPF}_{\text{II}})$</tex> to meet the rigorous broadband requirement for the targeted applications. At 4 K, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{LPF}_{\mathrm{I}}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{LPF}_{\text{II}}$</tex> show measured insertion loss of 0.06 and 0.05 dB at 10 MHz, respectively. Also, both designs attain excellent high-frequency signal suppression better than ~ 30 dB up to 40 GHz. Compared with the commercial product using discrete devices for the same application, the proposed designs achieve comparable specifications with a reduced area of up to ~ 46.1%. Moreover, the proposed design has the advantage of fully integrated multi-channel scalability.