Characterization and Analysis of On-Chip Microwave Passive Components at Cryogenic Temperatures

Abstract

This paper presents the characterization and modeling of microwave passive components in TSMC 40-nm bulk CMOS, including metal-oxide-metal (MoM) capacitors, transformers, and resonators, at deep cryogenic temperatures (4.2 K). To extract the parameters of the passive components, the pad parasitics were de-embedded from the test structures using an open fixture. The variations in capacitance, inductance and quality factor are explained in relation to the temperature dependence of the physical parameters, and the resulting insights on the modeling of passives at cryogenic temperatures are provided. Modeling the characteristics of on-chip passive components, presented for the first time down to 4.2 K, is essential in designing cryogenic CMOS radio-frequency integrated circuits, a promising candidate to build the electronic interface for scalable quantum computers.

Cryo-CMOS Interfaces for Large-Scale Quantum Computers

“…This is also clearly observed in passive components (Fig. 7) [16]. Still, several device properties, such as noise and self-heating, have not been in-depth investigated, and available simulation models are primitive when compared to CMOS EDA standards.…”

A Scalable Cryo-CMOS Controller for the Wideband Frequency-Multiplexed Control of Spin Qubits and Transmons

“…However, the noise power spectral density does not scale linearly with temperature and is only expected to be approximately 10× lower at 3 K compared with 300 K [26]. Some devices are not strongly affected by the cryogenic operation, e.g., the thin-film resistors used in this work show negligible change at 5 K compared with 300 K. The capacitance of metal-oxide-metal capacitors and the inductance of on-chip inductors are expected to slightly change at cryogenic temperatures, while the inductor quality factor can double [27].…”

“…An increase in the quality factor (Q) of a transformer by a factor of ∼2 expected at cryogenic temperatures, due to lower substrate losses and a higher metal conductivity [27], can affect the flatness of the transfer function. The transfer function can shift toward higher frequencies due to a reduction in effective inductance and capacitance of the transformer at cryogenic temperatures [27]. To compensate for these variations that are not well predictable, capacitor-and resistor-tuning networks were implemented at the windings of all matching networks.…”

A Wideband Low-Power Cryogenic CMOS Circulator for Quantum Applications

“…Inductors are expected to increase their Q factor by ∼2.6 times [28] due to the reduction of losses in the presence of a high resistivity substrate and reduced metal resistivity, while the value of inductance is going to reduce by ∼5% [28]. Capacitors are also going to have an increased quality factor due to reduced metal resistance, while the value of capacitance is going to increase by ∼3% [28]. The same will happen to all high-frequency differential lines that are going to experience lower insertion loss at 4.2 K.…”

“…While predictive models exist for room temperature, there are no accurate models for cryogenic circuit design. For this reason, measurements and modeling steps [28] have been carried out prior to the design phase to assess the performance of passive RF circuits at cryogenic temperature, to be used for a first prediction (since the circuit is mostly passive) of the circuit performance at 4.2 K.…”