JPH0547983B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave transistor such as a GaAs FET having a comb-shaped structure.

Microwave transistors such as GaAs FETs often have a comb-shaped structure to increase their output. FIG. 1A shows an example of a pattern of a conventional microwave GaAs FET having a comb structure.
In FIG. 1A, 1 indicates a gate bonding pad (input terminal), 2 indicates a drain bonding pad (output terminal), and 3 indicates a source bonding pad. A and B each indicate a unit transistor formed from one gate, one drain, and one source, and each unit transistor is connected in parallel by a gate power supply conductor 6, a drain power supply conductor 7, and a source power supply conductor 8. Further, the gate power supply conductor is connected to the gate bonding pad 1 by a connecting conductor 9. Figure 1B
shows a cross section taken along line X-X' in FIG. 1A. In FIG. 1B, 1a represents the gate A1, 2a represents the drain (AuGe), 3a represents the source (AuGe), and 4
is an n-type GaAs epitaxial layer, 5 is a semi-insulating layer
It is a GaAs substrate.

However, when microwave operation is performed using transistors such as those shown in FIG. 1A and B, unit transistor A and unit transistor B in the pattern are
Since the distances between the gate bonding pad 1 and the gate bonding pad 1 are different, the electrical lengths are different, and a phase difference occurs between the unit transistor A and the unit transistor B, resulting in a gain or output power that is smaller than the originally expected value. There is a drawback.

Note that the technique of dividing each unit transistor group and connecting it with a gate bonding pad and a connecting conductor of equal electrical length is described in Utility Model Application No. 56-
It is disclosed in Publication No. 112954. The technique disclosed in this publication divides a unit transistor group into a plurality of groups and connects each group to a bonding pad with a connecting conductor of equal length, so a closed circuit is formed between the groups. The drawback is that low frequency self-oscillation is likely to occur, resulting in a decrease in output power and gain.

An object of the present invention is to provide a power supply method that eliminates the phase difference between unit transistors in a comb-shaped microwave transistor and prevents a decrease in output power and gain.

In the present invention, a plurality of unit transistors having a drain electrode, a source electrode, and a gate electrode sandwiched therebetween are formed adjacent to each other in a direction perpendicular to the longitudinal direction of the source, drain, and gate electrodes, and A microwave transistor having a comb-shaped structure in which a gate electrode, a drain electrode, and a source electrode of a unit transistor are connected to a bonding pad by a gate power supply conductor, a drain power supply conductor, and a source power supply conductor, respectively. At least one of the gate or drain electrodes of the transistor is connected to a common connection conductor that commonly connects adjacent electrodes, and the gate power supply conductor or drain power supply conductor connected to the common connection conductor is connected to the bonding pad. By having a branch whose tip is converged into one on the side connected to the common connection conductor and divided into a plurality of pieces on the side connected to the common connection conductor, the This is designed to reduce the phase difference by approximating the length of the power supply conductor up to the bonding pad.

Examples of the semiconductor device according to the present invention will be shown below. Figure 2 shows a comb-shaped GaAs FET consisting of 12 unit transistors. 11 is a pad for gate bonding, 12 is a pad for drain bonding, and 13 is a pad for source bonding.

In this embodiment, each unit transistor 18a, 18
A plurality of drain electrodes, source electrodes, and gate electrodes of b,...181 are formed adjacent to each other at right angles to the longitudinal direction, and the gate electrode, drain electrode, and source electrode of the unit transistor are connected to the gate power supply conductor and the drain electrode, respectively. It is connected to each bonding pad 11, 12, 13 by a power supply conductor and a source power supply conductor. In this embodiment, 12 unit transistors 1 are supplied with power from one gate bonding pad 11.
8a, 18b, . Connection to the gate bonding pad 11 is made by connection conductors 15a and 15b.

By adopting the structure as shown in Fig. 2, it is possible not only to reduce the phase difference between, for example, the unit transistor 18d and the unit transistor 18f in the same figure, but also to connect the power supply conductor and the electrode to the common connection conductor. Since they are commonly connected, it is possible to easily bring out the original high frequency characteristics without generating unnecessary parasitic oscillation between the unit transistors.

Another embodiment is shown in FIG. In Figure 3, 2
1 is a pad for gate bonding, 22 is a pad for drain bonding, and 23 is a pad for source bonding. In this embodiment, the 16 unit transistors connected to the common connection part 25c connected in parallel are divided into eight regions, and the connection is made from the middle position of the common connection part of each divided unit transistor region 24. Connection to gate bonding pad 21 is made by conductor 25.

In the embodiment shown in FIG. 2, a plurality of unit transistors connected in parallel are divided into two, and the connection from the gate bonding pad 11 is connected to the connection conductor 1.
5a and 15b, but it goes without saying that the same effect can be expected even if the connection to the drain bonding pads is made separately. Furthermore, it goes without saying that the number of divisions is not limited to two. In the embodiment, there is one pad each for gate and drain bonding, but it is clear that the same effect can be obtained even if there are a plurality of pads for bonding.

As explained in detail above, according to the present invention, with an extremely simple pattern configuration, it is possible not only to reduce the electrical phase difference in each part of the pattern, but also to
Since all of the unit transistors are commonly connected by a common connection conductor, a decrease in output power due to parasitic oscillation can be avoided, so the effect of the present invention is extremely large in microwave transistors having a comb-shaped structure. be.

[Brief explanation of the drawing]

Figure 1 shows an example of a semiconductor device with a conventional structure.
FIG. 2 shows an embodiment of a semiconductor device according to the present invention.
FIG. 3 shows another embodiment of the semiconductor device according to the present invention. In the drawing, 11 and 21 are pads for gate bonding, 12 and 22 are pads for drain bonding, 13 and 23 are pads for source bonding, 15a, 15b, and 25 are connection conductors;
17 and 24 are unit transistor regions, and 15c and 25c are common connection conductors, respectively.

Claims (1)

[Claims] 1. A unit transistor having a drain electrode, a source electrode, and a gate electrode sandwiched therebetween,
A plurality of the source, drain, and gate electrodes are arranged adjacent to each other in a direction perpendicular to the longitudinal direction, and the gate electrodes of the plurality of unit transistors;
In a microwave transistor having a comb-shaped structure in which a drain electrode and a source electrode are connected to a bonding pad by a gate power supply conductor, a drain power supply conductor, and a source power supply conductor, respectively, the gate electrode or the drain electrode of the unit transistor At least one of the electrodes is connected to a common connection conductor that commonly connects adjacent electrodes, and the gate power supply conductor or drain power supply conductor connected to the common connection conductor is connected to the bonding pad. By having a branch whose tip is divided into a plurality of branches on the side connected to the common conductor, the power is supplied from each of the plurality of unit transistors to the bonding pad. A microwave transistor characterized by having a dendritic structure that approximates the length of a conductor. 2. The power supply conductor having the dendritic structure is formed by repeating a multi-step process in which the power supply conductor is derived from the converged side and divided at its tip in multiple stages, and is connected to each of the plurality of unit transistors from the bonding pad. 2. The microwave transistor according to claim 1, wherein all conductor lengths are the same.