CN106680594B - A kind of contactless measurement for LC oscillator characteristic parameter - Google Patents

Abstract

The invention discloses a non-contact measurement method for characteristic parameters of an LC oscillator. The method is to use an intermediate inductance to first have mutual inductance with the LC oscillator to be measured, and then to the external inductance, and use a vector network analyzer to measure the external inductance. The impedance curve of the LC oscillator can be calculated according to the curve and the method proposed in the present invention, including the resonant frequency and the quality factor of the LC oscillator. The method proposed by the invention can perform measurement when the LC oscillator to be tested is powered off without destroying the original circuit, and has the advantages of simple measurement structure, few steps and high measurement accuracy.

Description

A kind of contactless measurement for LC oscillator characteristic parameter

Technical field

The present invention relates to a kind of contactless measurements for LC oscillator characteristic parameter, more particularly, to a kind of base In the contactless measurement of inductance mutual inductance principle measurement LC oscillator characteristic parameter.

Background technique

The cost and complexity of semiconductor are all increasing in recent years, for highly integrated complicated circuit, non-cpntact measurement The characteristic parameter of core circuit becomes more and more important.LC oscillator has wide frequency range, circuit simple and flexible, at low cost etc. Advantage, thus be widely used in wireless communication system.The measurement method of traditional on piece LC oscillator is electric shape on the oscillator Under state, external measurement devices are driven by buffer circuit, buffer circuit not only increases power consumption, can also be to the performance parameter of oscillator It affects.Therefore, non-contact measurement LC oscillator performance parameter is particularly important.In addition, oscillator in RF application On-chip inductor it is all smaller, and piece external inductance is relatively large sized, and the coefficient of coup of two inductance is small, coupling effect is poor, Therefore, the LC oscillator characteristic parameter established on two inductance mutual inductance coupling models is unable to measure.

Summary of the invention

In order to solve the problems, such as background technique, the purpose of the present invention is to provide one kind to be used for LC oscillator characteristic The contactless measurement of parameter.Principle of the method proposed by the present invention based on three inductance mutual inductances can pass through a centre Coupling media of the inductance as LC oscillator and piece external inductance to be measured measures in the case where LC oscillator power down, and nothing Original circuit need to be destroyed, has the advantages that measurement structure is simple, step is few, measurement accuracy is high.

The technical solution adopted by the present invention is that:

Based on the principle of three inductance mutual inductances, using a middle inductor elder generation and LC oscillator mutual inductance to be measured, then and it is external Inductance mutual inductance can be mentioned using the impedance curve of vector network analyzer measurement external inductors according to the curve combination present invention Method out calculates the characteristic parameter of LC oscillator, including LC alternator resonant frequency and quality factor, measuring process are as follows:

(1) vector network analyzer is adjusted to single port impedance measurement mode, the input impedance of independent measurement external inductors. Certain frequency range is scanned centered on desired resonance frequency, obtains input impedance value Z at this time_in0Curve；It places again Middle inductor and LC oscillator to be measured, measure total input impedance value Z in the same way_inCurve；

(2) e (ω)=Real { Z is respectively obtained according to formula_in-Z_in0, g (ω)=Imag { Z_in-Z_in0}；

(3) remember e (ω) maximum e (ω_s) corresponding angular frequency is ω_s, two extreme points of g (ω) are denoted as g respectively (ω_p1) and g (ω_p2), corresponding angular frequency is ω_p1And ω_p2；

(4) using the quality factor q of the available LC oscillator to be measured of following formula_RAnd resonance frequency omega₀:

The invention has the advantages that:

It is measured in the case where LC oscillator power down, the oscillation of on-chip inductor very little in RF application can be measured Device, and without destroying original circuit, have the advantages that measurement structure is simple, step is few, measurement accuracy is high.

Detailed description of the invention

Fig. 1 is the top view and side view of embodiment HFSS simulation model.

Fig. 2 is the equivalent circuit schematic of embodiment simulation model.

Fig. 3 is input impedance (a) real part (b) imaginary part.

Fig. 4 is normalization input impedance (a) real part (b) imaginary part.

Fig. 5 is a kind of feasible inductance physical parameter.

Fig. 6 is the inductance electrical parameter obtained according to Fig. 5.

Specific embodiment

The working principle of the invention and embodiment are described further with reference to the accompanying drawings and examples.

The structural model figure that three inductance mutual inductances are built with HFSS, as shown in Fig. 1 (a) top view shown in, wherein electricity to be measured Feel L₃For the on-chip inductor of LC oscillator, its for illustrating oscillator is omitted in " LC oscillator capacitance and adjunct circuit to be measured " region His module, the resonance frequency of oscillator are 22GHz, with the lump port (Lumped port) etc. of 1 Ohmic resistance series connection 0.1pF Effect.Inductance L₃Size include Ir₃And W₃, L₂For middle inductor, the protection ring (guard of on-chip circuit can use herein Ring) it is used as L₂, design size includes Ir₂₁、Ir₂₂And W₂, L₂As long as size depending on the layout design of oscillator, simultaneously Ensure inductance L₂With inductance L₃The coefficient of coup cannot be too small, so inductance L₂With inductance L₃Spacing cannot be too big.L₁Outside for piece Inductance, design size include Ir₁And W₁, vector network analyzer is adjusted to single port impedance measurement mode, can be with independent measurement outside Portion inductance L₁Input impedance, while paying attention to inductance L₁And L₂The coefficient of coup can not be too small, otherwise the port VNA is measured humorous It shakes just very small.As shown in Fig. 4 (b) hierarchy chart, the thickness of three inductance is indicated remaining size by tm, inductance 3 and inductance 2 Spacing is ts₁, inductance L₂With inductance L₁Spacing be ts₂。

The equivalent circuit of Fig. 1 result is established, as shown in Fig. 2, inductance L₁Equivalent resistance be R₁, L₂Equivalent resistance be R₂, L₃Equivalent resistance be R₃, C_RAnd R_RIt is the equivalent capacity and resistance of oscillator respectively.Three current vectors are listed by three loops Equation:

Wherein:

Input impedance Z is obtained by formula (1) and (2)_in:

As shown in Figure 1, working as inductance L₁With inductance L₃Not when face-to-face face, the coefficient of coup k of the two₁₃It is just no better than 0, At this time:

It enablesAnd normalize Δ Z to ω, then,

Enabling e (ω) and g (ω) is the real and imaginary parts of Δ Z, then:

When e (ω) obtains maximum value:

At this time:

When g (ω) obtains maximum value:

At this time:

By formula (9), (10), (11) and (12), it can be deduced that:

By formula (13) and (14) it can be seen that inductance L to be measured₃Performance parameter can whether there is or not when mutual inductance by measuring Input impedance and obtain.

Taking into account the above, a feasible parameter designing is provided, in order to realize inductance L on PCB₃, inductance L₃Line width W₁ 2mil had better not be lower than, the line width of 0.05mm is used in the design, specific physical parameter is as shown in figure 5, according to physics Parameter is as shown in Figure 6 using the electrical parameter that Q3D software extracts.

The real part Δ R and imaginary part Δ X of Δ Z can be calculated by the solid line in Fig. 3 by bringing the electrical parameter of Fig. 6 into formula (5) It is shown, normalized Δ R/ ω and Δ X/ ω are further obtained as shown by the bold lines in fig, by HFSS software emulation Fig. 1 Model obtain Δ R and Δ X as shown in the dotted line in Fig. 3, further obtain in normalized Δ R/ ω and Δ X/ ω such as Fig. 4 Shown in dotted line.

It can see theoretical curves by Fig. 3 and Fig. 4 to be identical with simulation curve, the simulation curve of Δ R/ ω is (i.e. Dotted line in Fig. 4) extreme point be 23.2GHz, the extreme points of theoretical curves (i.e. solid line in Fig. 4) is 23GHz, is substituted into respectively Formula (9) calculates the emulation of alternator resonant frequency and notional result is 22.13GHz and 21.94GHz, and the two relative error is about It is 0.86%.On the other hand, the peak value normalization imaginary part Δ X/ ω indicated by formula (11) opposite there are two symbol, frequency point Not Wei 22.8GHz and 23.2GHz, similarly, by HFSS simulate Lai two extreme value dot frequencies be respectively 22.9GHz and 23.6GHz。

To sum up, feasibility of the invention is demonstrated using the derivation of equation and modeling and simulating.

Claims (1)

1. a kind of contactless measurement for LC oscillator characteristic parameter, it is characterised in that: use a middle inductor LC oscillator mutual inductance first and to be measured, then with external inductors mutual inductance, the impedance using vector network analyzer measurement external inductors is bent Line can combine method proposed by the present invention calculate the characteristic parameter of LC oscillator according to the curve, including LC oscillator is humorous Vibration frequency and the specific measuring process of quality factor are as follows:

(1) vector network analyzer is adjusted to single port impedance measurement mode, the input impedance of independent measurement external inductors；To Certain frequency range is scanned centered on the resonance frequency of prestige, obtains input impedance value Z at this time_in0Curve；Centre is placed again Inductance and LC oscillator to be measured, measure total input impedance value Z in the same way_inCurve；

(2) e (ω)=Real { Z is respectively obtained according to formula_in-Z_in0, g (ω)=Imag { Z_in-Z_in0}；

(3) remember e (ω) maximum e (ω_s) corresponding angular frequency is ω_s, two extreme points of g (ω) are denoted as g (ω respectively_p1) and g (ω_p2), corresponding angular frequency is ω_p1And ω_p2；

(4) using the quality factor q of the available LC oscillator to be measured of following formula_RAnd resonance frequency omega₀: