| Millimeter wave (mmW) technologies have been widely used in high-data-rate wireless communications, car radar and imaging, etc. Benefited from the continuous progress of silicon CMOS technologies, it is now possible to implement mmW integrated circuits (ICs) on silicon-based processes instead of â…¢-â…¤ compound semiconductor processes which are much more expensive. The costs of mmW ICs are thereby expected to be reduced to realize extensive applications. On-chip passive components are important circuit elements that have great impact on the electrical performance of the circuits. However, there exist remarkable differences between the on-chip passive devices used in mmW field and those used in low-frequency field, such as structures, performances, and loss mechanisms, which bring great difficulties to the modeling of mmW on-chip passive devices. The lack of models consequently restricts the development of mmW IC design. Therefore, it is an urgent problem that need to be solved to establish the models of on-chip passive devices for mmW uses with high-precision, high efficiency and broadband fitting ability through accurate characterization of the behaviors of on-chip passive devices in the mmW conditions.Transfer function describes the relationship between the input and output currents/voltages of a continuous, linear, and time-invariant electric network in frequency-domain. On the one hand, the poles and zeros of the transfer function are determined by the intrinsic properties of the circuit network, such as topology and complexity. On the other hand, the poles and zeros of the transfer function determine the key features and performance of the circuit network, such as bandwidth, gain and phase. Therefore, transfer function is an important bridge that contacts the topology of a circuit network and its electric performances.Based on the above-mentioned role of the transfer function and the problems faced by the modeling of mmW on-chip passive devices, this thesis has mainly completed the following innovative work:1. A novel transfer function analysis method for equivalent circuit models of on-chip passive devices is presented. Through the analysis of the transfer functions for the models, including1-Ï€,2-Ï€ and T models, the pros and cons of equivalent circuit topology are investigated, and the fitting abilities of the models are evaluated.1-Ï€ and T models are proved to be able to describe the distribution effect of spiral inductors from both theoretical and experimental aspects. A reasonable explanation for the singularity problem of2-Ï€ models is given. The proposed method is verified by the S-parameter on-wafer measurement up to40GHz for ten CMOS on-chip spiral inductors.2. A new broadband scalable model combining the advantages of physics-based equivalent circuit model and broadband behavioral model is proposed for on-chip spiral inductors, as well as the effective parameter extraction method. Considering the parasitics of on-chip spiral inductors in the mmW band, the high-frequency fitting ability of the original equivalent circuit model is improved with the vector fitting (VF) method. The proposed model is verified by the S-parameter on-wafer measurement up to40GHz for eighteen CMOS on-chip spiral inductors. Good agreement between the simulated and the measured results is achieved within the entire measured frequency range.3. The proposed transfer function analysis methods are also applied to the equivalent circuit models of on-chip transmission lines and transformers. This method can be used to choose the topology of a distributed model segments and the total number of the cascade segments by considering the poles and zeros of the model. It is also proved that the fitting ability of the equivalent circuit model is determined by the number of poles and zeros in the model instead of the total number of model parameters. Based on the VF method, broadband equivalent circuit models for on-chip transmission lines and transformers are proposed. The proposed model and method are verified by the S-parameter on-wafer measurement up to50GHz and100GHz for the on-chip transmission line and transformer, respectively. The proposed transfer function analysis method can be used as the criterion for choosing the equivalent circuit topology of on-chip passive components. |
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