On-Chip Diplexer Design for Travelling Wave Parametric Amplifiers for Quantum Computers
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Projektarbete, avancerad nivå
Project Report, advanced level
Project Report, advanced level
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Model builders
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Abstract
This report presents the design and simulation of an on-chip diplexer intended for Traveling-
Wave Parametric Amplifier (TWPA) applications. The device targets a 4–8 GHz source signal
and a 10 GHz pump frequency, with the objective of maximizing the pump suppression and
minimizing the insertion loss for the source signal. A cut-off frequency of 9 GHz was established
to satisfy matching criteria of S11 < −20 dB and pump suppression of S21 < −25 dB.
The final series-first diplexer design successfully meets the pump suppression requirement of at
least −25 dB at 10 GHz but does not fully maintain the −20 dB matching across the entire
bandwidth. Simulations performed in both ADS and Sonnet confirm that, despite not meeting
the matching goal, the diplexer likely maintains acceptable performance, suggesting that the
initial matching requirement may have been overly stringent.
As the design has not yet been fabricated, practical measurements are pending. The close agreement
between the ADS and Sonnet simulations demonstrates that fast preliminary simulations
in ADS can effectively guide and streamline the design process. Future work involves fabricating
the device, measuring its real-world performance, and iterating the design. An elliptical filter
approach is proposed for subsequent design iterations to potentially achieve improved matching
and suppression.