CN101520813A - Nonlinear equivalent circuit of gallium arsenide PIN diode and application thereof - Google Patents

Abstract

The invention discloses a nonlinear equivalent circuit of a gallium arsenide PIN diode, which belongs to the field of radio frequency/microwave technology. The equivalent circuit consists of parasitic resistance, parasitic inductance, reverse capacitance, forward capacitance, transition region capacitance and switches. Wherein, the reverse capacitor, the forward capacitor, and the transition zone capacitor are connected in parallel and connected in series with the switch, and the switch selects between the reverse capacitor, the forward capacitor, and the transition zone capacitor according to the change of the input signal voltage. Parasitic resistance and parasitic inductance are connected in series in an equivalent circuit. The invention realizes the large-signal harmonic balance simulation including the gallium arsenide PIN diode, and is compatible with existing mainstream EDA tools. The invention directly uses formulas to define the nonlinearity of the device, which solves the problem that passive components are difficult to describe the nonlinearity of the device, and can be used as a sub-circuit for substituting a circuit containing gallium arsenide PIN diodes for harmonic balance simulation.

Description

Nonlinear Equivalent Circuit of GaAs PIN Diode and Its Application

technical field

The invention relates to the technical field of radio frequency/microwave devices, in particular to a nonlinear equivalent circuit of a gallium arsenide PIN diode and an application thereof.

Background technique

Gallium arsenide PIN diodes are rich in nonlinearity, and their capacitance value is several hundred pF above the turn-on voltage, which is dominated by diffusion capacitance; when reverse biased, the capacitance value is very small, mainly dominated by space charge region capacitance. The gallium arsenide PIN diode is quickly switched between the on state and the reverse state by controlling the working state of the gallium arsenide PIN diode through a large microwave signal, so that the capacitance value changes drastically and thus exhibits rich nonlinearity. GaAs PIN diodes are also called Step-Recovery-Diodes (SRDs), which are mainly used in broadband synchronous signal generators, broadband frequency synthesizers, and terahertz radiation sources.

Accurate large-signal device models are required when designing circuits utilizing the nonlinearity of SRDs. Since the nonlinearity of SRD mainly comes from the change of the impedance of the intrinsic region with the signal, the key to establishing a large signal model is how to accurately describe the nonlinearity of the impedance of the intrinsic region.

Through the small-signal model, the impedance parameters of the GaAs PIN diode in the non-certified area can be extracted, such as contact resistance, P+/N+ area resistance, package parasitic resistance, and lead inductance. These parameter values do not change with the signal, and can be directly applied to the large signal model by applying the small signal parameter values.

The established gallium arsenide PIN diode nonlinear equivalent circuit must not only accurately characterize the nonlinearity of the device, but also be compatible with mainstream EDA software. It can be directly applied to the harmonic balance simulation of the circuit, and the parameter extraction is convenient.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a gallium arsenide PIN diode nonlinear equivalent circuit, so as to realize the harmonic balance simulation of the circuit including the gallium arsenide PIN diode.

Described technical scheme is as follows:

The nonlinear equivalent circuit of the gallium arsenide PIN diode of the present invention is composed of parasitic resistance, parasitic inductance, reverse capacitance, forward capacitance, transition zone capacitance and selection switch; the reverse capacitance, forward capacitance and transition zone The capacitor is connected in parallel with the selection switch in series; the selection switch selects among the reverse capacitance, forward capacitance and transition region capacitance according to the change of the input signal voltage of the equivalent circuit; the parasitic resistance and Parasitic inductance is connected in series in the equivalent circuit.

The nonlinear equivalent circuit of gallium arsenide PIN diode of the present invention,

When the input voltage of the equivalent circuit is greater than the turn-on voltage, the selection switch is connected to the forward capacitance, and the capacitance value of the forward capacitance is determined by the diffusion capacitance of the gallium arsenide PIN diode;

When the input voltage of the equivalent circuit is less than zero volts, the selection switch is connected to the reverse capacitance, and the capacitance value of the reverse capacitance is determined by the charge region capacitance of the gallium arsenide PIN diode space;

When the input voltage of the equivalent circuit is between zero volts and the turn-on voltage, the selection switch is connected to the transition region capacitance, and the capacitance value of the transition region capacitance is determined by the diffusion of the gallium arsenide PIN diode The capacitance and the space charge layer capacitance are jointly determined.

In the nonlinear equivalent circuit of the gallium arsenide PIN diode of the present invention, the capacitance values of the reverse capacitance, forward capacitance and transition region capacitance are determined by the following formula:

$\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; v</span>}& <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">C</figure-callout></span><figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&phi;</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; \&phi;</span>}}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\frac{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">C</figure-callout></span><figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; )</span>}\text{<span class="notranslate"> \&phi;</span>}& <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; fv</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">C</figure-callout></span><figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&phi;</span>}& <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; \&Greater\; Equal;</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; )</span>\end{array}\right.$

Among them, Q is the charge stored in the I region; C _r is the capacitance value of the reverse capacitor; C _f is the capacitance value of the forward capacitor; v is the input voltage value of the equivalent circuit; Φ is the turn-on voltage.

In the nonlinear equivalent circuit of the gallium arsenide PIN diode of the present invention, the parasitic resistance is the ohmic contact resistance of the gallium arsenide PIN diode, including the ohmic contact of the P ⁺ region and the N ⁺ region of the gallium arsenide PIN diode resistance.

In the nonlinear equivalent circuit of the gallium arsenide PIN diode of the present invention, the parasitic inductance is lead inductance, including the inductance of the upper electrode lead and the lower electrode lead of the gallium arsenide PIN diode.

The application of the nonlinear equivalent circuit of the GaAs PIN diode of the present invention, when the input voltage of the equivalent circuit is greater than the turn-on voltage, the selection switch is connected with the forward capacitance, and the forward capacitance of the The capacitance value is determined by the diffusion capacitance of the GaAs PIN diode;

When the input voltage of the equivalent circuit is less than zero volts, the selection switch is connected to the reverse capacitance, and the capacitance value of the reverse capacitance is determined by the charge region capacitance of the gallium arsenide PIN diode space;

When the input voltage of the equivalent circuit is between zero volts and the turn-on voltage, the selection switch is connected to the transition region capacitance, and the capacitance value of the transition region capacitance is determined by the diffusion of the gallium arsenide PIN diode The capacitance and the space charge layer capacitance are jointly determined.

In the application of the non-linear equivalent circuit of the GaAs PIN diode of the present invention, the capacitance values of the reverse capacitance, forward capacitance and transition region capacitance are determined by the following formula:

$\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; v</span>}& <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">C</figure-callout></span><figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&phi;</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; \&phi;</span>}}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\frac{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">C</figure-callout></span><figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; )</span>}\text{<span class="notranslate"> \&phi;</span>}& <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; fv</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">C</figure-callout></span><figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&phi;</span>}& <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; \&Greater\; Equal;</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; )</span>\end{array}\right.$

Among them, Q is the charge stored in the I region; C _r is the capacitance value of the reverse capacitor; C _f is the capacitance value of the forward capacitor; v is the input voltage value of the equivalent circuit; Φ is the turn-on voltage.

The beneficial effects of the technical solution provided by the invention are:

The non-linear equivalent circuit and application of the gallium arsenide PIN diode provided by the present invention describe the change in the working state of the device caused by the large signal, which is embodied in the non-linearity of the capacitance, and the capacitance is different in the three states The capacitance value makes the device generate rich higher harmonics. The equivalent circuit simulation was carried out in Agilent-ADS by using SDD, and the nonlinearity of the device was defined directly with the formula, which solved the problem that the passive components were difficult to describe the nonlinearity of the device. Harmonic balance simulation. By comparing the experimental results and the simulation results of the equivalent circuit, it is found that the circuit accurately matches the actual characteristics of the device.

Description of drawings

Fig. 1 is the non-linear equivalent circuit diagram of gallium arsenide PIN diode provided by the present invention;

Figure 2 is the carrier distribution curve in the I region under the control of only DC current;

Figure 3 is the carrier distribution curve in the I region under the action of microwave large signal only;

Figure 4 is the carrier distribution curve in the I region under the combined action of DC and microwave signals;

Fig. 5 is a charge-voltage relationship diagram;

Fig. 6 is the non-linear equivalent circuit of the gallium arsenide PIN diode that represents the three-state capacitance with SDD;

Figure 7 is a comparison of the input power-output power relationship between the zero bias test and the equivalent circuit simulation;

Figure 8 is a comparison of the input power-output power relationship between the test of -3V and the equivalent circuit simulation;

Figure 9 is a comparison of the input power-output power relationship diagrams of the 1.2V test and the equivalent circuit simulation;

Fig. 10 is the monitoring figure of transmission line method measuring ohmic contact resistance;

Fig. 11 is the test result and fitting curve of the ohmic contact resistance measured by the transmission line method.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

The research on the nonlinearity of GaAs PIN diodes is carried out in the state of large injection, that is, the input microwave signal is so large that only the microwave signal can drive it to work normally when it is not in the state of DC bias. In the study of GaAs PIN diodes in the state of large injection, only the charge storage effect of its intrinsic region (I region) is considered, and the influence of other regions is ignored, such as ohmic contact resistance, heavily doped region resistance, surface leakage conductance, junction impedance and parasitic impedance. The research method first qualitatively analyzes the carrier distribution, and secondly uses the diffusion equation to obtain the precise carrier concentration.

When the PIN tube only transmits DC signals, the heavily doped region injects electrons and holes into the I region, and the concentration is much higher than the equilibrium carrier concentration in the I region. The carrier concentration is the highest at the boundary of the I region, and on a certain section inside the I region, the carrier concentration is the lowest, and the lowest concentration value is higher than or equal to the equilibrium carrier concentration of the I region itself, as shown in Figure 2 . Since the concentration of minority carriers implanted from the I region to the heavily doped region is very low, the recombination of carriers mainly occurs in the I region. The diffusion of holes in the P+ region and electrons in the N+ region to the I region is related to both the electric field and the concentration gradient.

When there is a sufficiently large microwave signal to drive the gallium arsenide PIN diode, enough to make it work normally, the carrier concentration at the boundary of the I region is established by diffusion, but the concentration at the boundary decays quickly, and the higher the signal frequency, the The concentration decays faster at the border of zone I. In other regions of the I region, the carrier concentration remains unchanged, which is still the equilibrium carrier concentration of the I region itself, as shown in Figure 3. The microwave signal changes with time, but the concentration distribution in region I does not change. The transmission of microwave signals is realized by the vibration of carriers in their average positions. At this time, as long as there is a direct current path, direct current can still flow through the gallium arsenide PIN diode through carrier recombination. Due to the large injection state, the carrier concentration at the boundary of the I region, that is, the junction, is much higher than the carrier concentration inside the I region, so the junction is equivalent to an electrical short circuit, and the impedance of the junction can be ignored in the large injection state.

When the DC and microwave signals drive the GaAs PIN diode together, the DC signal increases the charge uniformly in the entire I region, while the microwave signal only increases the carrier concentration at the boundary of the I region, and does not change the carrier inside the I region. Concentration, as shown in Figure 4.

Through the above-mentioned large signal modulation analysis of the I-region charge (impedance) of the GaAs PIN diode, it can be seen that the carrier concentration in the I-region under large injection is mainly determined by the DC bias, so the resistance is linear. Under the combined effect of DC and external signals, when the total input voltage is greater than the turn-on voltage, the I region is full of carriers, the resistance is small, and the capacitance is dominated by diffusion capacitance, and the capacitance value is large; when the total input voltage is less than zero, The carrier concentration in zone I is low, and the resistance value is very large, which is equivalent to an open circuit. The capacitance is mainly in the space charge zone, and the capacitance value is very small; when the total input voltage is between zero volts and the turn-on voltage, the resistance value is still very large. , while the capacitance value is composed of the diffusion capacitance and the space charge region capacitance.

Due to the nonlinear modulation of the capacitance by the external large signal, the device exhibits abundant nonlinearity. From the analysis of the edge sum of the device charge, the change of the capacitance value can be clearly found. As shown in Figure 5, when the input voltage is less than zero, the charge-voltage relationship is a linear relationship with a small slope; when the input voltage is greater than the turn-on voltage, the charge-voltage relationship is a linear relationship with a large slope; when the input voltage is between zero volts and Between the turn-on voltages, the charge-voltage slope shows a gradual increase as the voltage becomes larger. The slope of the charge-voltage relationship can be interpreted as a capacitance value in a physical sense. It can be seen that the capacitance value changes with the input voltage, and the specific charge-voltage relationship expression is shown in formula (1).

$\mathrm{<span\; class="notranslate">\; Q</span>}<span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; v</span>}& <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">C</figure-callout></span><figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&phi;</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}\mathrm{<span\; class="notranslate">\; \&phi;</span>}}{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>\frac{{{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">C</figure-callout></span><figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; )</span>}\text{<span class="notranslate"> \&phi;</span>}& <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; )</span>\\ {\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; fv</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; C</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">C</figure-callout></span><figure-callout\; id="2"\; label="C\; r"\; filenames="A200910080194E00122.png,A200910080194E00132.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; \&phi;</span>}& <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; \&Greater\; Equal;</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; )</span>\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, Q is the charge stored in the I region, _Cr is the reverse capacitance value, C _f is the forward capacitance value, v is the voltage value, and Φ is the turn-on voltage.

According to the above analysis, the gallium arsenide PIN diode equivalent circuit of the present invention can be obtained. The equivalent circuit is composed of parasitic resistance, parasitic inductance, reverse capacitance, forward capacitance, transition zone capacitance and selection switch; the reverse capacitance, forward capacitance and transition zone capacitance are connected in parallel and then connected in series with the selection switch; the selection switch is based on The change of the input signal voltage of the equivalent circuit, choose between the reverse capacitance, the forward capacitance and the capacitance of the transition region; in addition, the parasitic resistance and parasitic inductance are connected in series in the equivalent circuit.

According to the working principle of gallium arsenide PIN diode, a switch is used to select between three-state capacitors, so as to describe the nonlinear relationship between capacitance and voltage. At the same time, the forward conduction resistance in parallel is used to represent the forward differential resistance when the gallium arsenide PIN diode is turned on. When the device is not turned on, the forward resistance value is very large, which is an approximate open circuit. control, regardless of the external signal.

Other parameters in the equivalent circuit, such as parasitic resistance and parasitic inductance, are extracted through the small-signal equivalent circuit, and these parameter values are independent of the external signal.

Regarding the characterization of the tri-state capacitor, since there are no ready-made components corresponding to it in the existing mainstream EDA tools, it needs to be described by a formula editor. In Agilent-ADS, a nonlinear element based on the formula is provided, that is, the symbol defines the device Signal-Defined-Device (SDD). An SDD contains more than one port, and the current-voltage relationship of each port must be defined. In this equivalent circuit, a single-port SDD is used to define a three-state capacitor, see Figure 6. Since the direct current-voltage relationship of the capacitor is difficult to express, it is expressed in the form that the differential value of the charge to time is equal to the current. Specifically, a weight coefficient of 1 is used to represent the charge differential, that is, I[1,1]=Q(_v1).

In order to verify the accuracy of the equivalent circuit, experimental measurements were carried out, and the input power-output power relationship was tested at DC zero bias, -3V and +1.2V, and the turn-on voltage of the GaAs PIN diode was 1.1V. The test results are compared with the model simulation, and the results prove that the equivalent circuit can accurately match the actual measured values of the device, as shown in Figures 7, 8, and 9.

The parasitic resistance includes ohmic contact resistance, P+ region resistance, and N+ region resistance; the ohmic contact resistance is used to characterize the ohmic contact resistance of the P+ region and the N+ region, the P+ region resistance is used to characterize the doping resistance of the P+ region, and the N+ region resistance is used for To characterize the doping resistance of the N+ region. Parasitic inductance means lead inductance, including the inductance of the upper electrode lead and the lower electrode lead, which cannot be ignored at high frequencies.

The parameter extraction of parasitic resistance and parasitic inductance adopts the extraction method of linear equivalent circuit, which is described in detail as follows.

Since the capacitive reactance and inductive reactance can be ignored at high frequencies, the value of the parasitic inductance can be obtained from the imaginary part matrix Im{ABCD(1,2)} of the ABCD parameter. The network analyzer measures the scattering parameters (S parameters) of the GaAs PIN tube, and uses Agilent-ADS to convert the S parameters into cascade parameters (ABCD parameters), and calculates the parasitic inductance value by using formula (2).

L＝Im{ABCD(1,2)}/ω     (2)

In actual use, the P+ region and the N+ region adopt a highly doped structure to reduce loss, and the doping concentration is about 10 ¹⁹ /cm ^-3 , so the resistance of this part can be ignored. The main part of the parasitic resistance is the ohmic contact resistance, and the N-type GaAs ohmic contact process is mature, and the contact resistance value is very low, which can be ignored; while the ohmic contact resistivity of the P-type GaAs is still relatively large, it needs to be considered . The measurement of ohmic contact resistivity adopts the transmission line method, and its measurement graph is shown in Figure 10. The spacing between the metal pads in the monitoring pattern is 10 μm, 20 μm, 30 μm, 40 μm and 50 μm in sequence. The resistance values between transmission lines with pitches of 10 μm, 20 μm, 30 μm, 40 μm, and 50 μm were sequentially measured. Taking the spacing as the independent variable, plot the resistance value, as shown in Figure 11, and adopt linear fitting to it. The good agreement between the measurement results and the fitted line indicates good ohmic contact characteristics. After calculation, the contact resistivity was 1×10 ^-7 Ω·cm ² .

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (7)

1, a kind of nonlinear equivalent circuit of gallium arsenide PIN diode is characterized in that, described equivalent electrical circuit is made up of dead resistance, stray inductance, reciprocal capacitance, forward electric capacity, zone of transition electric capacity and selector switch; Connect with described selector switch after described reciprocal capacitance, forward electric capacity and the parallel connection of zone of transition electric capacity; Described selector switch is selected between described reciprocal capacitance, forward electric capacity and zone of transition electric capacity according to the variation of described equivalent electrical circuit applied signal voltage; Described dead resistance and stray inductance are connected in the described equivalent electrical circuit.

2, the nonlinear equivalent circuit of gallium arsenide PIN diode according to claim 1 is characterized in that,

When the input voltage of described equivalent electrical circuit during greater than cut-in voltage, described selector switch is connected with described forward electric capacity, and the capacitance of described forward electric capacity is determined by the diffusion capacitance of described gallium arsenide PIN diode;

When the input voltage of described equivalent electrical circuit lied prostrate less than zero, described selector switch was connected with described reciprocal capacitance, and the capacitance of described reciprocal capacitance is determined by the charged region electric capacity in described gallium arsenide PIN diode space;

When the input voltage of described equivalent electrical circuit when zero lies prostrate between the cut-in voltage, described selector switch is connected with described zone of transition electric capacity, and the capacitance of described zone of transition electric capacity is determined jointly by the diffusion capacitance and the space charge layer capacitance of described gallium arsenide PIN diode.

3, the nonlinear equivalent circuit of gallium arsenide PIN diode according to claim 1 is characterized in that, the capacitance of described reciprocal capacitance, forward electric capacity and zone of transition electric capacity is determined by following formula:

$Q=\left\{\begin{array}{cc}{C}_{r}v& (v\&le;0)\\ \frac{C_f-C_r}{2\mathrm{\&phi;}}{(v+\frac{C_r\mathrm{\&phi;}}{C_f-C_r})}^2-\frac{C_r^2}{2(C_f-C_r)}\text{\&phi;}& (0<v<\mathrm{\&phi;})\\ C_{\mathrm{fv}}-\frac{C_f-C_r}{2}\mathrm{\&phi;}& (v\&GreaterEqual;\mathrm{\&phi;})\end{array}\right.$

Wherein, Q is that the I district stores electric charge; C _rCapacitance for reciprocal capacitance; C _fCapacitance for forward electric capacity; V is the input voltage value of equivalent electrical circuit; Φ is a cut-in voltage.

4, the nonlinear equivalent circuit of gallium arsenide PIN diode according to claim 1 is characterized in that, described dead resistance is described gallium arsenide PIN diode ohmic contact resistance, comprises the P of described gallium arsenide PIN diode ⁺District and N ⁺The ohmic contact resistance in district.

5, the nonlinear equivalent circuit of gallium arsenide PIN diode according to claim 1 is characterized in that, described stray inductance is a lead-in inductance, comprises the top electrode lead-in wire of described gallium arsenide PIN diode and the inductance of bottom electrode lead-in wire.

6, the application of the nonlinear equivalent circuit of the described gallium arsenide PIN diode of claim 1, it is characterized in that, when the input voltage of described equivalent electrical circuit during greater than cut-in voltage, described selector switch is connected with described forward electric capacity, and the capacitance of described forward electric capacity is determined by the diffusion capacitance of described gallium arsenide PIN diode;

When the input voltage of described equivalent electrical circuit lied prostrate less than zero, described selector switch was connected with described reciprocal capacitance, and the capacitance of described reciprocal capacitance is determined by the charged region electric capacity in described gallium arsenide PIN diode space;

When the input voltage of described equivalent electrical circuit when zero lies prostrate between the cut-in voltage, described selector switch is connected with described zone of transition electric capacity, and the capacitance of described zone of transition electric capacity is determined jointly by the diffusion capacitance and the space charge layer capacitance of described gallium arsenide PIN diode.

7, the application of the nonlinear equivalent circuit of gallium arsenide PIN diode according to claim 6 is characterized in that, the capacitance of described reciprocal capacitance, forward electric capacity and zone of transition electric capacity is determined by following formula:

$Q=\left\{\begin{array}{cc}{C}_{r}v& (v\&le;0)\\ \frac{C_f-C_r}{2\mathrm{\&phi;}}{(v+\frac{C_r\mathrm{\&phi;}}{C_f-C_r})}^2-\frac{C_r^2}{2(C_f-C_r)}\text{\&phi;}& (0<v<\mathrm{\&phi;})\\ C_{\mathrm{fv}}-\frac{C_f-C_r}{2}\mathrm{\&phi;}& (v\&GreaterEqual;\mathrm{\&phi;})\end{array}\right.$

Wherein, Q is that the I district stores electric charge; C _rCapacitance for reciprocal capacitance; C _fCapacitance for forward electric capacity; V is the input voltage value of equivalent electrical circuit; Φ is a cut-in voltage.

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