Enhanced Circuit Model And Parameter Extraction Of 28nm RF On-chip Spiral Inductors

In the past ten years,ultra-large-scale integrated circuits have developed rapidly,with smaller circuit size and more advanced process technology.Nowadays,the mainstream process generation has entered the 20 nm node.However,along with this,the complexity of the process structure increases,and the physical parasitic effects become much more severe,which seriously affects the circuit performance.Moreover,with the rapid developments of the wireless market,the application frequency band of the radio frequency integrated circuit(RFIC)has been continuously rising,and has reached several tens of GHz,where the parasitic phenomenon becomes more obvious.In order to realize low-cost,low-power dissipation,high-integration and highperformance RF integrated circuits,RF on-chip spiral inductors are particularly important,and its accurate model is the key to correct circuit simulation.At present,for spiral inductor models of deep nanotechnology(28nm),there are many problems: incomplete parasitic effects,poor physical interpretation of model parameters,difficulty in parameter extraction,large amount of calculation,ambiguity in extraction standards.What's more,most of models are verified only with deep submicron devices in the frequency band up to 20 GHz.Based on the current situation,this paper proposes an enhanced single-? equivalent circuit model,and a simple and clear analytical parameter extraction method.Then,a single-double ? network transformation algorithm is presented,with which the enhanced single-? model extend into a more accurate double ? equivalent model.Finally,different structures are employed to verify the model.The main contents and results of this thesis are as follows.Firstly,in order to improve the description of loss mechanism such as metal loss,substrate loss and port coupling,an enhanced single ? topology is proposed basing on the traditional single ? model.It has been found that owing to metal loss,such as skin effect and proximity effect,the effective series resistance of the spiral inductor increases first and then decreases,and the effective series inductance decreases with the increase of frequency.Two RL subcircuit structures designed can reasonably explain this phenomenon.A RC parallel network is added to simulate the loss caused by the coupling effect of metal via the substrate.At the same time,the description of the coupling resistance and capacitance between the ports,namely and ,is added,which also plays a role of improving the accuracy of the high frequency band.Secondly,based on the above enhanced single ? model,this paper then presents a simple and effective method to extract model parameters.After obtaining the results of the real layouts using high-precision electromagnetic field tool(EMX),we can directly extract parameters from the port measurement parameters(S or Y parameters),with no need for complicated and massive optimization calculations.In this paper,the extraction standard and extraction procedure are clearly and detailed,and the rationality of the method is verified by a real example.Then six on-chip spiral inductors with different structural parameters are used to verify the enhanced single ? model and analytical parameter extraction method.It's proved that the model has high precision.The average error of Y parameter is 0.62%,L and Q are 1.7156% and 3.6471%,respectively,and the frequency of max Q is also close to the real structure in the range of 0-40GHz(up to self-resonant frequency).Then,with the enhanced single ? model,this paper proposes a single-double ? network conversion algorithm using isoelectric potential analysis.The algorithm is free from the physical analysis based cumbersome and complex parameter extraction method,and arbitrary single-double ? network conversion mode.It accords with the electromagnetic theory and gets rid of the limitation of the topological.Finally,by the feat of the algorithm,we obtain an enhanced double ? equivalent model with the enhanced single ? model.Two ways are adopted to prove the wide-band and high-precision characteristics of the model.On the one hand,the average error of the Y parameters of all structures is 0.37%,L and Q are 0.4983% and 1.8651% respectively in the range of 0-40GHz(up to self-resonant frequency).Whatever it is,Y parameter,L,Q or maximum Q frequency,the enhanced double ? model is of high accuracy and is better than the the single ? one,especially in high frequency band.On the other hand,the cross-coupled oscillator circuit is applied to test the overall accuracy of the model.Both models have high precision,and the resonant frequency errors are 1.543% and 0.829%,respectively.The enhanced double ? model is also of higher fittness.The work of this thesis targets at the deep nano-process(28nm)RF on-chip spiral inductor modeling,proposing an enhanced single ? model with analytical parameter extraction method,and an enhanced double ? broadband high-precision model with a conversion algorithm.They are all proved highly accurate over a wide frequency band and suitable for practical applications,which can provide reference and help for RF spiral inductor modeling,as well as RFIC design and wide-band applications.