RU2403650C1 - High-power rf and microwave transistor - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: in RF and microwave transistors, conductor contacts (CC) connecting a coating and an emitter package terminal, and the CCs connecting the coating and emitter regions of transistor cells (TC) are arranged on the opposite sides of one capacitor coating of an internal input matching LC-link. And some of the last CCs are arranged on metallised strips (MS) limited to a coating edge and perpendicular notches. For this purpose, the lengths and widths of the MS are specified such that to actualise partially or completely the appropriate related stabilising resistance (SR) between the TC emitter regions and the condenser coating providing a uniform heating of the TC in operation conditions due to the MS resistances proportional to the MS relation. It allows reducing the area of the TC structures being under emitter voltage and thereby reducing stray transfer 'collector-emitter' capacitance.

EFFECT: higher power gain factor of a RF and microwave transistor.

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Description

The claimed invention relates to semiconductor electronics and can be used in the construction of high-power RF and microwave semiconductor devices.

A powerful RF and microwave transistor is known, which contains a dielectric base on which a capacitor is placed, the first lining of which is connected to wire conductors with an input electrode and metallization of the first active regions of transistor cells located on a semiconductor substrate, and the second lining is connected to a common output electrode and metallization of the second active areas of transistor cells [1]. In order to stabilize the distribution of thermal power across the transistor cells and reduce positive thermal feedback in the emitter circuit of each transistor cell, a stabilizing resistance r _e is sequentially included in the form of a thin-film or diffusion ballast resistor. The presence of ballast resistors reduces the probability of transistor structure failure due to thermal breakdown and allows to increase its output power [2].

The disadvantage of this transistor is the reduction of the gain in power K _UR with increasing uniformity of power distribution across transistor cells, provided by an increase in the resistance of ballast resistors r _e [3].

In another powerful RF and microwave transistor, the ballast resistors, each formed near the corresponding transistor cell, have different resistances r _ei , i = 1, ..., N, determined by the spatial relative position of the transistor cells. This allows us to increase the input resistances of transistor cells subject to overheating, thereby reducing their thermal positive feedback, without increasing the input resistances of other transistor cells and leading to a noticeable decrease in _SD , increasing the input resistance of the transistor structure as a whole.

The disadvantage of this transistor structure is the increase in stray capacitance of the "emitter-collector" due to the increase in the area of individual ballast resistors, which leads to a decrease in power gain and efficiency of the transistor [4].

The closest in combination of features is a powerful RF and microwave transistor, in which the rows of conductors connecting the first plate to the input electrode and metallization of the first active areas of the transistor cells are connected to the plate at its opposite edges [5].

An increase in the emitter-collector capacitance with an increase in the series of stabilizing resistances in the emitter circuit of the transistor cells, which increases the output power of the transistor and reduces the probability of transistor failure due to thermal breakdown, prevents the gain from reaching the maximum value of the transistor power.

An increase in the resistances of the stabilizing resistors r _ei leads to an increase in the power dissipated in the collector [6], therefore, the power transmitted to the load [7]. However, this increases the length of the resistor and its area, and, consequently, the area of the upper plate of the parasitic emitter-collector capacitor with a _FE formed by a resistor and metallization of the emitter above the collector. A common consequence of an increase in resistance r _ei is an increase in the emitter-collector capacitance and a decrease in the gain in power of the transistor K _UR [4].

The claimed invention is intended to reduce the stray capacitance of the collector-emitter of the transistor by reducing the area of the elements under the emitter potential and located on the semiconductor substrate, and when it is implemented, the gain in power of the transistor can be increased.

The above problem is solved in that in a known high-power high-frequency and microwave transistor containing a dielectric base on which a capacitor is placed, the first lining of which is connected to the base terminal of the housing and the metallization pads of the base regions located on the semiconductor substrate of the transistor cells, one edge of the second lining is connected with an emitter terminal of the case, and the opposite edge of the second plate is connected by N conductors to the metallization pads of the emitter regions transistor cells, wherein the edge of said second electrode connected to the contact pads on both sides of the point of attachment to the facing recesses made M≤N conductors, and the resistance of the compounds with the emitter regions of the second capacitor plate are r _ek, k = 1, ..., N, according to the invention , the widths of the sections between the recesses w _j and the half-sum of the lengths of the adjacent edges of the recesses to the left and right of the sections l _j satisfy the conditions:

where Δ _k and Δ _j are the distances from the connection points of the respective conductors located between the recesses to the nearest edge of the second plate.

The technical result obtained by carrying out the invention, namely, the reduction of power losses in the operating frequency band of the transistor, is achieved due to the fact that tracks are formed in the gaps of the recesses in the capacitor plate formed in accordance with conditions (3), the resistance of which allows partially or fully realize the difference between the resistances r _ek , thereby reducing the area of ballast resistors with increased values of r _ek , or partially, or fully realize the whole set of resistances, stabilizing resisting r _ek , thereby reducing or reducing to zero the area of all ballast resistors. Since ballast resistors are located on the semiconductor substrate above the collector region and are under the emitter potential, a decrease in their area leads to a decrease in the stray capacitance of the collector-emitter transistor.

The drawing schematically shows the inventive powerful RF and microwave transistor.

Powerful RF and microwave transistor consists of a dielectric base 1, on which are located a capacitor 2 and a semiconductor substrate 3 with transistor cells 4, for which it is a common collector region. The first lining 5 of the capacitor is connected by conductors 6 to the contact pads 7 of the metallization of the base areas of the transistor cells 4 and is directly in contact with the metallization 8 of the base terminal of the housing. One edge of the second plate 9 is connected by conductors 6 to the emitter terminal of the housing 10, and the opposite edge is connected by N conductors 6 to the contact pads 11 of the metallization of the emitter regions of the transistor cells 4.

The first lining 5 in the drawing is shown lower, and the second lining 9 is upper. Ballast resistors 12 contact pads 11 and metallization of the emitter regions of transistor cells 4 with their opposite edges 12. Recesses 13 are formed in the second lining 9 of the capacitor 2, so that the points of connection of the individual conductors 6 to the lining 9 are in the spaces of the recesses 13. In the drawing, shown: a collector terminal 14 connected to a semiconductor substrate 3 by collector metallization 15, as well as a conductive beam 16, through which the contact pads 7 of the base areas of the transistor cell 4 is additionally connected by wire conductors 6 with metallization 8 of the base terminal in order to reduce its inductance.

When a high-power RF and microwave transistor operates in a circuit with a common base from the connection points M≤N of conductors 6 located between the recesses 13 to the edge of the second plate 9, the spreading of emitter currents over the surface of the plate is limited by metal strips whose width w _k is equal to the distance between adjacent edges of their constituent the recesses 13, and the effective length l _k is equal to half the lengths of these edges minus the distance Δ _k from the point of attachment of the conductor 6 to the proximal edge of the plate 9.

The resistance of metal strips, including resistance due to the induction of eddy currents in the first (lower) lining of the capacitor and ohmic resistance:

и

толщины скин-слоя соответственно в первой и второй обкладках конденсатора, µ₀=4π·10^-7 Гн/м - магнитная постоянная в СИ, µ₁ и µ₂ - относительные магнитные проницаемости материалов первой и второй обкладок.where w _k and l _k are the width and effective length of the strip; D and σ ₁ - thickness and conductivity of the material of the first lining of the capacitor; h and σ ₂ are the thickness and conductivity of the material of the second (lower) lining;

and

the thickness of the skin layer, respectively, in the first and second plates of the capacitor, μ ₀ = 4π · 10 ^-7 GN / m is the magnetic constant in SI, μ ₁ and μ ₂ are the relative magnetic permeabilities of the materials of the first and second plates.

The optimal distribution of power to transistor structures 2 to achieve its maximum value and at the same time realize the maximum value of K _{UR is} achieved by implementing an optimal set of resistances r _ek , k = 1, ..., N, included between the contact metallization of the emitter regions of the transistor cells 4 and the second capacitor plate 9 internal input matching LC link.

As follows from formulas (2) - (4), the resistance of metal strips r _{floor k is} directly proportional to their effective length l _k and inversely proportional to the width w _k . Thus, the fulfillment of condition (1) makes it possible to fully or partially realize the difference in the resistances r _ek necessary for the optimal distribution of power among transistor cells, due to the difference in resistances r _{floor k} , in turn, created due to different effective length l _k and width w _k gaps between the recesses 13. The increase in resistance r _ek for reducing power dissipation cell transistor connected to k-th conductor 6 with said second electrode of the capacitor 9 with respect to the power dissipation of transistor yache ki from series resistance in the emitter circuit r _ej connected to plate 9 j-th conductor may be accomplished by decreasing the width w _{k k-th} interval between the recesses and the effective length l _k. In addition, due to the resistance of the metal strip r _{floor k} , the resistance r _ek ≥r _{floor k} can be partially or fully realized. This provides a reduction, up to zero, of the resistances of the ballast resistors 12 with resistances r _bk = to _ek -r _{floor k} , therefore, reducing or minimizing the length and area of the ballast resistors. Thus, the area of the upper plate of the parasitic capacitor and the through-collector-emitter capacitance are reduced, which provides an increase in the gain in power of the transistor structure.

Limiting the change in the width of the strips to the right-hand side of inequality (1) excludes the realization of the realized ratios of the strip resistances r _{floor k} / r _{floor j} beyond the necessary ratios of stabilizing resistances r _ek / r _ej .

LITERATURE

1. Hale R.I. Hybrid Transistor / R.I. Hale. - US Patent 4393392, Int. C1. H01L 23/02; US C1. 357/74. - 07/12/83.

2. Nikishin V.I. Design and production technology of high-power microwave transistors / V.I. Nikishin, B.K. Petrov, V.F.Synorov and others - M .: Radio and communications, 1989. - p. 91.

3. Ibid., P. 18, 30, 38.

4. Ibid., Pp. 8, 11, 37.

5. RU 2328058 C1, GOUVPO Voronezh State University, June 17, 2008.

6. Nikishin V.I. Design and production technology of high-power microwave transistors / V.I. Nikishin, B.K. Petrov, V.F.Synorov and others - M .: Radio and communications, 1989. - p. 102.

7. Ibid., P. 6, 7.

8. Evstigneev A.S. Strip line parameters on a semiconductor substrate / A.S. Evstigneev // Electronic Technology. Ser.2, Semiconductor devices. - 1981. - Issue 5. - p. 32-37.

Claims (1)

Powerful RF and microwave transistor containing a dielectric base on which a capacitor is placed, the first lining of which is connected to the base terminal of the case and the metallization pads of the base regions located on the semiconductor substrate of the transistor cells, one edge of the second plate is connected to the emitter terminal of the case, and the opposite the edge of the second plate is connected by N conductors to the contact pads of the metallization of the emitter regions of the transistor cells, and from the edge of the second plate connected with pads, on both sides of the points of attachment to the M≤N conductor plate, recesses are made, and the resistance of the connections of the emitter regions with the second capacitor plate is r _ek , k = 1, ..., N, characterized in that the width of the sections between the recesses w _j and half-sums of the lengths of adjacent edges of the recesses to the left and to the right of the sections l _j satisfy the conditions:

,
where Δ _k and Δ _j are the distances from the connection points of the respective conductors located between the recesses to the nearest edge of the second plate.