Advanced hybrid power amplifier design

A hybrid radio frequency (RF) power device is provided which comprises: a flange (10) and an arrangement of die blocks (30) disposed about the flange (10), where the arrangement of die blocks (30) has die blocks (30a-30d) organized in a plurality of rows and a plurality columns, where the device may further comprise a substrate (15) disposed between the flange (10) and the arrangement of die blocks (30), and a first die block (30a) connected to a second die block (30b) by a conductor (42c) having a length of half a wavelength.

TECHNICAL FIELD
 The present invention relates generally to radio frequency (RF)
 transmission devices, and more specifically to designs for a hybrid power
 devices, such as amplifiers, adapted for use in RF devices, and to a
 method of arranging die on a hybrid power device flange.
 BACKGROUND OF THE INVENTION
 Hybrid power devices are used in many electronic designs. For example,
 radio frequency communications devices, such as cellular
 telecommunications devices, use hybrid power devices such as hybrid power
 amplifiers. As cellular telecommunications devices offer users a wider
 array of features, more circuitry is needed to implement these features,
 and thus a demand for more powerful hybrid amplifiers has arisen. For
 example, in 1997 radio frequency devices typically employed a hybrid
 amplifier that provided from 10 to 30 Watts of power. However, by the end
 of 1998, engineers were designing devices that were demanding hybrid power
 amplifiers which could provide power in the range of 80-120 Watts of
 power, and it was apparent that even more powerful amplifiers would be
 required in the near future to accommodate even more telecommunications
 features.
 Power amplification in a hybrid power amplifier is accomplished through the
 use of hybrid transistors that are also called cells. The power output of
 a single cell is limited, and so to increase the power output of a hybrid
 power amplifier, more cells must be used in a device. The clustering or
 grouping of cells into a concentrated area forms what is called a die. A
 die may consist of any number of cells (a grouping of, for example, 28
 cells is common), and groupings of cells are generally made to achieve a
 discrete and predictable amount of power amplification (gain).
 Typically, a die is arranged in a modular unit that includes the necessary
 mechanical and electrical connections that link the cells to appropriate
 points on a hybrid power amplifier, as well as to various devices that
 adjust an input and an output impedance. The various devices which adjust
 the input and output impedance include capacitors, resistors, and
 connections such as wire bonds, that are chosen, in part, for their
 impedance. The modular unit that includes the combination of the die, it's
 connections, and the various devices is called a "die block." Like cells,
 die blocks may be grouped together (effectively increasing the number of
 cells) on a flange to increase the power output of a hybrid power
 amplifier.
 FIG. 1 (prior art) illustrates a common die block 30. Generally, the die
 block 30 receives an input signal on input connection 32, passes the input
 signal from the input connection 32 through die a 38, where the input
 signal is processed, so that an amplified output signal may be carried
 from the die block 30 on output connection 33.
 More specifically, input connection 32 is a conductor which is electrically
 connected to a metal oxide semiconductor (MOS) CAP 34 that is in turn
 electrically linked to a plurality of conductors called wire bonds 36 that
 are coupled to, and carry the input signal to, the die 38. Both the MOS
 CAP 34 and the wire bonds 36 bias the input impedance to match the input
 impedance of the die 38. The die 38 is in turn coupled to conductors
 called output wire bonds 37 that are connected to an output MOS CAP 35
 which then is linked to the output connection 33. As was the case on the
 input side of the die block, the output wire bonds 37 and the output MOS
 CAP 35 are used to adjust the output impedance of the die block 30.
 Accordingly, in operation, an input signal arrives to the die block 30 at
 input connection 32. The input signal travels through input connection 32
 to the MOS CAP 34 that bridges the input signal to the wire bonds 36
 (which function as a bias circuit by adjusting the input impedance of the
 circuit). Next, the input signal is then passed through the wire bonds 36
 to the die 38. In the die 38 the input signal causes the die to produce an
 output signal which is equal to the input signal multiplied by a
 predetermined gain. The output signal (power output) is generated in the
 output wire bonds 37, and the output wire bonds 37 carry the output signal
 to output MOS CAP 35. Like the MOS CAP 34, the output MOS CAP 35 adjusts
 the output impedance of the die block 30 to more closely match the output
 impedance of the circuit (not shown) to which the die block 30 is
 connected. From the MOS CAP 35, the output signal travels off the die
 block 30 on the output connection 33.
 FIG. 2 (prior art) illustrates a hybrid power amplifier built on a flange
 10 having two die blocks 30 mounted thereon. The flange 10 has mountings
 12 or other means for connecting the flange 10 to its parent RF device
 (not shown), which may be, for example, a cellular telephone. The flange
 10 supports a substrate 15 on which various structures are disposed. For
 example, the flange 10 may support a bias circuit 20 comprising various
 resistors, capacitors and other electrical devices used to adjust the
 input and output impedance of the hybrid power amplifier to match the
 input and output impedance of the circuit to which the hybrid power
 amplifier is attached. The bias circuit 20 may be placed on or off the
 flange 10, and is illustrated in FIG. 2 as being on the flange 10 (the
 bias circuit 20 is represented generally as a dashed block 20 to emphasize
 that it may be placed on or off the flange 10). In addition, the flange 10
 supports die blocks 30 (each die block 30 is shown here as a rectangle,
 with a dark line representing the general orientation of the die 38 in a
 die block 30). The flange 10 also supports additional structures, such as
 input/output conductors called an input pin 40 and an output pin 41, and
 conductors called an input transmission line 42 and an output transmission
 line 43. The input pin 40 and input transmission line are electrically
 linked. Likewise, the output pin 41 and the output transmission line 43
 are also electrically coupled. The input transmission line 42, and output
 transmission line 43, are also coupled to the die blocks 30.
 In operation, input pin 40 carries an input signal to the input
 transmission line 42 which then transfers the input signal to die blocks
 30. The input pin 40 and the input transmission line 42 may also bias the
 hybrid power amplifier to match the input impedance of the circuit to
 which the hybrid power amplifier is connected (not shown). After
 processing the input signal, die blocks 30 produce the output signal. The
 output signal travels from the die blocks 30 to output transmission line
 43, which then sends the output signal to output pin 41. The output signal
 travels off the flange 10 through output pin 41. Note that the die 38 on
 the hybrid power amplifier (and the corresponding die blocks 30) are
 separated by a distance S.sub.1. Note further that die blocks 30 are
 arranged in a single column down a vertical axis, here called the "y"
 axis. In this orientation, a signal "travels" generally in a horizontal
 path along a horizontal "x" axis, which is illustrated as a left to right
 travel path in FIG. 2.
 As discussed above, to implement more powerful hybrid power amplifiers,
 more cells must be placed on each flange. Increasing the number of cells
 on a flange is accomplished by using larger die blocks, or by placing more
 die blocks on a flange. To place more die blocks on a flange, designers
 have taken the approach shown in FIG. 3.
 FIG. 3 (prior art) illustrates a flange 10 having four die blocks 30
 disposed thereon in an "in-line" arrangement. This arrangement is called
 "in-line" because the die blocks are arranged in a vertical line along the
 y-axis. The in-line flange arrangement of FIG. 3 is structurally similar
 to the flange arrangement FIG. 1 in that it is designed to amplify an
 electrical signal propagating generally from input pin 40 through the die
 block 30 and off the flange 10 via output pin 41. The in-line arrangement
 of die blocks 30 shown in FIG. 3 provides for simplicity in the design and
 manufacture of a hybrid power amplifier. However, the vertical in-line
 arrangement of the die blocks 30 across the flange 10 place the die blocks
 30 in close proximity to a first perimeter 22 and a second perimeter 24.
 In addition, the distance between the die blocks 30 has now decreased as
 shown by spacing S.sub.2.
 The design of FIG. 3, where die are arranged vertically on a flange,
 suffers several shortcomings. First, there is not enough vertical space to
 continue mounting additional die on the flange in the in-line arrangement,
 and thus, the total power output of a die seems to be mechanically limited
 by the vertical height (or length) of the flange 10.
 Second, in operation, each cell typically generates a discrete amount of
 heat, and the decreased spacing between die, as indicated by S.sub.2,
 results in die concentrating (which means that there is less flange area
 between the die to be used for heat dissipation). Thus, die concentrating
 results in not only the concentration of cells for power, but also the
 concentrating of cells as heat sources. This causes the temperature of the
 die blocks to increase at the die, and causes the temperature of the
 flange at the die concentrations to increase as well (the flange typically
 drains heat through the mounts 12, which function as heat sinks), which
 may cause device failure, or even ignite the circuit. Also, though less
 dangerous, inefficient heat dissipation raises the temperature of
 surrounding electrical systems which reduces circuit efficiency.
 Another disadvantage of the prior art is that die that are physically
 separated (such as the die in proximity to the perimeters) by random
 distances are often out of phase with each other electrically. Devices
 which are out of phase electrically suffer from unequal spacing conditions
 which leads to power cancellation, and thus, inefficient power
 transmission. Furthermore, the disadvantages of poor heat dissipation and
 inefficient power transmission in hybrid power devices have the
 consequence of reducing the bandwidth performance of the hybrid power
 devices.
 Therefore, there exists the need for an advanced hybrid power device and
 method that are capable of accommodating more power amplification per
 flange area. The present invention provides such a device and method.
 SUMMARY OF THE INVENTION
 In one embodiment, the present invention is a hybrid radio frequency (RF)
 power device comprising a flange and an arrangement of die blocks
 organized about the flange in a plurality of rows and a plurality columns.
 The device may further comprising a substrate disposed between the flange
 and the arrangement of die blocks.
 The arrangement of die blocks may comprise a first die block connected to a
 second die block by a conductor having a length which is a fraction of a
 wavelength of a RF power device operation wavelength, such as one half of
 a wavelength. The hybrid RF power device may incorporate a Wilkerson
 hybrid in an input connection. In addition, the die blocks may be
 organized into two rows and three columns.
 One embodiment of the present invention provides a hybrid RF power device
 having a first row and a second row and a first column and a second
 column. In this embodiment, an arrangement of die blocks comprises a first
 die block located in the first row and the first column, a second die
 block located in the first row and the second column, a third die block
 located in the second row and the first column, and a fourth die block
 located in the second row and the second column. Each die block has a
 corresponding die block input and a corresponding die block output. This
 embodiment may further comprise an input connection for connecting an
 input pin to the first die block input, the second die block input, the
 third die block input, and the fourth die block input where a first
 portion of the input connection lies generally between the first row and a
 first perimeter of a substrate, and a second portion of the input
 connection lies generally between the second row and a second perimeter of
 a substrate. This embodiment may also provide for an output connection for
 connecting an output pin to the first die block output, to the second die
 block output, to the third die block output, and to the fourth die block
 output.
 The embodiment may further provide for a first link, having a length of
 approximately one half of a wavelength of a RF power device operation
 wavelength, that connects the first die block to the second die block. A
 second link, having a length of approximately one half of a wavelength of
 a RF power device operation wavelength, connects the third die block to
 the fourth die block. The input connection could be a microstrip
 transmission line.
 The embodiments of the device discussed above may be made or used based on
 die arrangements, rather than die block arrangements. In other words, the
 die blocks in the embodiments summarized above can be replaced by the die
 components of the die blocks.
 The present invention is also a method of increasing the RF power output of
 a hybrid power device. The method comprises the step of arranging a
 plurality of die blocks on a flange into a plurality of rows and a
 plurality columns. This method may further include the step of connecting
 a first die block to a second die block with a microstrip transmission
 line having a length of half of a wave length of a RF power device
 operation wavelength.
 The present invention increases the available output power per a fixed
 flange area. The thermal dissipation of the present advanced hybrid power
 amplifier design is more efficient than prior art thermal dissipation
 because the spacing between die can be increased, providing more flange
 area for thermal conductivity. The present invention achieves additional
 efficiencies when implemented with a half-wavelength spacing between die
 because such a spacing eliminates the unequal phase condition problem of
 the prior art and has the added benefit of generating a push-pull effect
 in the hybrid power amplifier. Furthermore, the geometric arrangement of
 die block disclosed herein allows greater numbers of die to be mounted per
 fixed flange area, resulting in the ability to simultaneously increase the
 power output, realize better thermal dissipation, and achieve the desired
 push-pull effect. Because of these and other advantages, the present
 invention will achieve a higher bandwidth performance.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
 FIG. 4 illustrates one embodiment of a radio frequency (RF) hybrid power
 device according to the teachings of the present invention. The device of
 FIG. 4 is a hybrid RF power amplifier having an arrangement of die blocks
 30, comprised of a first die block 30a, a second die block 30b, a third
 die block 30c, and a fourth die block 30d, disposed, in two rows and two
 columns, on a flange 10. The present invention does not require the
 alteration of the die blocks 30a-30d, as used by the prior art hybrid RF
 power devices, and it may be noted that the die blocks 30a-30d are
 generally comprised of silicon, gallium, or arsenic cells. Also, flanges,
 such as flange 10, are available in a wide variety of designs and sizes,
 and any flange configured for hybrid RF power transmission can be used
 with the present invention. The flange 10 has mountings 12 for securing
 the device to a structure, such as a cell phone.
 A substrate 15 is shown disposed between the arrangement of die blocks 30
 and the flange 10. The substrate 15 may be any hybrid power device
 substrate material, and is preferably an aluminous substrate. To more
 clearly present the arrangement of the die blocks 30, the flange 10 is
 shown illustrated along a vertical "y" axis and a horizontal "x" axis.
 As illustrated in FIG. 4 the first die block 30a and the second die block
 30b are physically aligned in a first horizontal row, illustrated
 generally as x.sub.1. Accordingly, the third die block 30c and the fourth
 die block 30d are likewise situated along a second horizontal row,
 x.sub.2. Furthermore, first die block 30a and third die block 30c are
 commonly placed in a first vertical column which is illustrated generally
 as y.sub.1. The second die block 30b and the fourth die block 30d are
 commonly placed in a second vertical column, y.sub.2. The die blocks 30a,
 30b, 30c, 30d, are oriented so that the input connections 32 are adjacent
 to either a nearest substrate perimeter. Thus, first die block 30a and
 second die block 30b have input connections 32 which are adjacent to a
 first substrate perimeter 22. Likewise, the third die block 30c and the
 fourth die block 30d have input connections 32 which are adjacent to a
 second substrate perimeter 24.
 The device of FIG. 4 also includes the electrical connections and devices
 used to carry input signals arriving at the device to the die blocks
 30a-30d, as well as the electrical connections and devices used to carry
 output signals from the die blocks 30a-30d and off the device. Thus, to
 carry electrical signals into the device, the device has an input pin 40
 attached to a first node P. Node P is the connection between input pin 40
 and a conductive input transmission line implemented in this embodiment as
 an input microstrip transmission line 42. Input microstrip transmission
 line 42 is disposed on substrate 15 and is coupled to each die block
 30a-30d through the input connections 23 of each die block 30a-30d.
 Likewise, to carry signals off of the device, the device also includes an
 output pin 41 which connects to an output transmission line implemented as
 an output microstrip transmission line 43. As shown in FIG. 4, the output
 microstrip transmission line 43 is coupled to the die blocks 30a-30d
 through the output connections 33.
 The input microstrip transmission line 42 may implement a Wilkinson hybrid
 (typically realized by electrically separating the first node P from the
 first die block 30a, and the second die block 30c, by a distance equal to
 the length of one-fourth the wavelength of the operational wavelength of
 the device). Furthermore, as illustrated in FIG. 4, the input microstrip
 transmission line 42 has a link portion 42a adjacent to and approximately
 parallel with the first substrate perimeter 22, and a link 42c defined as
 the input microstrip transmission line portion between a fourth node S and
 a fifth node T, where the fourth node S is the electrical connection
 between the input connection of the first die block 30a and the input
 microstrip transmission line 42, and the fifth node T is the electrical
 connection between the second input connection of the second die block 30b
 and the input microstrip transmission line 42. The link 42c has a length
 defined as a fractional wavelength of the operational wavelength of the
 device. Preferably, the length of the link 42c is equivalent to half of a
 wavelength of the operational wavelength of the device. The preferred
 length of the link 42c is illustrated in FIG. 4 as lambda over 2, which is
 shown separating the first vertical axis y.sub.1 and the second vertical
 axis y.sub.2.
 Likewise, the input microstrip transmission line 42 has a link 42b adjacent
 to and approximately parallel with the substrate perimeter 24, and a
 second link 42d defined as the input microstrip transmission line portion
 between the second node Q and the third node R, where the second node Q is
 the electrical connection between the input connection of the third die
 block 30c and the input microstrip transmission line 42, and the third
 node R is the electrical connection between the input connection of the
 fourth die block 30d and the input microstrip transmission line 42. The
 link 42d has a length defined as a fractional wavelength of the
 operational wavelength of the device. Preferably, the length of the link
 42d is equivalent to half of a wavelength of the operational wavelength of
 the device. As with the first portion, the preferred length of the link
 42d is illustrated in FIG. 4 as lambda over 2, which is shown separating
 the first vertical axis y.sub.1, and the second vertical axis Y.sub.2.
 Note also that a half-wavelength separation of die blocks is also
 implemented on the output microstrip transmission line 43 of the die
 blocks 30a-30d. Thus, the preferred length of the output microstrip
 transmission line 43, which is maintained between the output connections
 33 of the die blocks 30a-30d as shown in FIG. 4, is a half of a wavelength
 of the operational wavelength of the device. Furthermore, the output pin
 41 connects to the output microstrip transmission line 43 where the output
 microstrip transmission line 43 intersects with the output connections 33
 of the second die block 30b and the fourth die block 30d.
 The half wavelength design utilized by the link 42c and the link 42d is
 called an impedance repeater. The impedance repeater design effectively
 places selective groups of die blocks, and thus, their respective die, in
 parallel electrically, while allowing for the physical separation of die
 blocks across a flange. Specifically, referring to FIG. 4, die blocks 30a
 and 30b are physically separated but electrically in parallel, and die
 blocks 30c and 30d are physically separated but electrically in parallel.
 Furthermore, the half wavelength design on the inputs and outputs allows
 the die blocks to function as push-pull amplifiers, increasing the quality
 of the power transmission. Specifically, die block 30a is 180 degrees out
 of phase with die block and 30b, and die block 30c is 180 degrees out of
 phase with die block 30d. Accordingly, die blocks 30a and 30c are in phase
 with each other (and thus, turn on together), and die blocks 30b and 30d
 are in phase with each other (and likewise turn on together). Thus, die
 blocks 30a and 30c can be said to have a push-pull effect with respect to
 die blocks 30b and 30d. Furthermore, because of the half wavelength design
 of the output microstrip transmission line 43, the output of the die
 blocks 30a and 30b combine with the output of die blocks 30b and 30d at
 the output pin 41 such that output signal of the amplifier is an amplified
 version of the input signal. Note that other wave length portions can be
 used. Furthermore, it is worth noting that the half wavelength design also
 naturally suppresses even order harmonic interference.
 In operation, input pin 40 carries an input signal to input microstrip
 transmission line 42 which relays the input signal on to die blocks 30a,
 30b, 30c, and 30d. The input pin 40 and the input microstrip transmission
 line 42 may also bias the input impedance of the hybrid power amplifier to
 match the input impedance of the circuit to which the hybrid power
 amplifier is connected (not shown). After processing the input signal, die
 blocks 30a-30d produce the output signal and send the output signal to the
 output microstrip transmission line 43. The output microstrip transmission
 line 43 then sends the output signal to the output pin 41 which carries
 the output signal off the flange. In the orientation of the present
 invention, an electrical signal travels generally in a horizontal path
 along a horizontal "x" axis from left to right, and thus provides for
 mechanical operation which is transparent to a user of the prior art
 devices.
 The orientation of the die blocks 30a-30d into rows x.sub.1, x.sub.2 and
 columns y.sub.1, y.sub.2 as demonstrated by die blocks 30a, 30b 30c, and
 30d, permits more die blocks to be placed on a fixed flange area (making
 more powerful devices possible). The arrangement of die blocks into rows
 and columns makes the placement of a specific number of die blocks on a
 fixed flange area easier than in-line placement. Furthermore, the
 orientation of the die blocks into rows and columns provides for an
 increased separation, shown in FIG. 4 as S.sub.3, of the die of the die
 blocks, as compared to a prior art design having the same number of die
 blocks, for example, S.sub.2 in FIG. 3. The physical separation of the die
 38 of the die blocks 30a-30d in this manner provides thermal dissipation
 advantages. This increased separation means that the heat generated by the
 die 38 is spread out (as opposed to the heat being concentrated in a small
 area, as is a problem with the in-line arrangement separation, S.sub.2,
 shown in FIG. 3). In fact, some designs limit available RF power output
 because of the heat generated due to the higher die temperatures of the
 prior art.
 Another advantage of this configuration is that it is easier to match a
 lower die impedance. Because the die blocks are effectively operating in
 pairs (for example, 30a and 30b are operating as a pair, and 30c and 30d
 are operating as a pair), a lower transformation ratio is needed for a
 fixed flange space to match the impedance of a network. In other words, in
 operation, the present invention sees the network not as from the point of
 view of four die blocks in parallel, but from the point of view of two
 pairs of die blocks operating in parallel. This lower transformation ratio
 improves the bias of the device which also increases the active bandwidth
 of the device.
 The physical separation of die 38 also eliminates the problem of power
 cancellation encountered by the prior art in-line design. Power
 cancellation in the prior art is caused by the unequal phase conditions
 which exist at the output connections of the prior art in-line design.
 This is because the die blocks of the in-line approach are separated by
 distances that force the choice of selecting more die on the flange,
 better heat dissipation, or better phase placement. Also, the present
 invention realizes less phase shift on the die block inputs as well as
 better heat dissipation. Accordingly, the present invention harmonizes
 competing inconsistencies of the prior art to produce both heat
 dissipation and phase harmonization benefits that result in lower overall
 power loss.
 Of course, it may be desired to add additional die blocks to a flange in a
 manner that embraces the advantages of the present invention. FIG. 5
 portrays one embodiment of the present invention that accommodates
 multiple die blocks in a cascaded format, here incorporating a fifth die
 block 30e and a sixth die block 30f. The embodiment of FIG. 5 realizes the
 spacing advantage of the present invention. For comparative purposes, the
 flange sizes and substrate sizes of FIG. 3 and FIG. 5 are drawn equal.
 Note that the spacing limitations of the in-line configuration illustrated
 in FIG. 3 prohibit the placement of more than four die blocks on the
 flange. However, the configuration of the present invention easily
 accommodates six (or more) die blocks on the same flange area while taking
 advantage of the spacing advantages of the present invention.
 Thus, FIG. 5 illustrates one embodiment of a radio frequency (RF) hybrid
 power amplifier according to the teachings of the present invention. The
 hybrid RF power amplifier has an arrangement of die blocks 30, comprised
 of a first die block 30a, a second die block 30b, a third die block 30c, a
 fourth die block 30d, the fifth die block 30e and the sixth die block 30f,
 disposed in two rows and three columns, on a flange 10. A substrate 15 is
 shown disposed between the arrangement of die blocks 30 and the flange 10.
 As illustrated in FIG. 5 the first die block 30a, the second die block 30b,
 and the fifth die block 30e are physically aligned in a first horizontal
 row. Accordingly, third die block 30c, fourth die block 30d, and sixth die
 block 30f are likewise situated along a second horizontal row.
 Furthermore, first die block 30a and third die block 30c are commonly
 placed in a first vertical column. The second die block 30b and fourth die
 block 30d are commonly placed in a second vertical column, and the fifth
 die block 30e and the sixth die block 30f comprise a third vertical
 column. The die blocks 30a, 30b, 30c, 30d, 30e, and 30f are oriented so
 that the input connections 32 are adjacent to either a nearest substrate
 perimeter. Thus, first die block 30a, second die block 30b and fifth die
 block 30e have input connections 32 which are adjacent to a first
 substrate perimeter 22. Likewise, the third die block 30c, the fourth die
 block 30d, and the sixth die block 30f have input connections 32 which are
 adjacent to a second substrate perimeter 24.
 The hybrid power amplifier of FIG. 5 also provides the electrical
 connections used to carry input signals arriving at the device to the die
 blocks 30a-30f, as well as the electrical connections to carry output
 signals from the die blocks 30a-30f and off the device. Thus, to carry
 electrical signals into the device, the device has an input pin 40
 attached to a first node P. Node P is the connection between input pin 40
 and a conductive input transmission line implemented in this embodiment as
 an input microstrip transmission line 42. Input microstrip transmission
 line 42 is disposed on substrate 15 and is coupled to each die block
 30a-30f. Likewise, to carry signals off of the device, the device also
 includes an output pin 41 which connects to an output transmission line
 implemented as an output microstrip transmission line 43. As shown in FIG.
 5, the output microstrip transmission line 43 is coupled to the die blocks
 30a-30f.
 Furthermore, as illustrated in FIG. 5, the input microstrip transmission
 line 42 has a first portion adjacent to and approximately parallel with
 the first substrate perimeter 22, and a first link 42c defined as the
 input microstrip transmission line portion between a fourth node S and a
 fifth node T, where the fourth node S is the electrical connection between
 the input connection of the first die block 30a and the input microstrip
 transmission line 42, and the fifth node T is the electrical connection
 between the second input connection of the second die block 30b and the
 input microstrip transmission line 42. The link 42c has a length defined
 as a fractional wavelength of the operational wavelength of the device.
 Preferably, the length of the link 42c is equivalent to half of a
 wavelength of the operational wavelength of the device. The preferred
 length of the link 42c is illustrated in FIG. 5 as lambda over 2.
 Likewise, the input microstrip transmission line 42 has a link 42b adjacent
 to and approximately parallel with the second substrate perimeter 24, and
 a link 42d defined as the input microstrip transmission line portion
 between the second node Q and the third node R, where the second node Q is
 the electrical connection between the input connection of the third die
 block 30c and the input microstrip transmission line 42, and the third
 node R is the electrical connection between the input connection of the
 fourth die block 30d and the input microstrip transmission line 42. The
 link 42d is a length defined as a fractional wavelength of the operational
 wavelength of the device. Preferably, the length of the second portion 42d
 is equivalent to half of a wavelength of the operational wavelength of the
 device. As with the link 42d the preferred length of the second portion is
 illustrated in FIG. 5 as lambda over 2. Furthermore, FIG. 5 also shows a
 link 42e, which connects fourth node T to fifth node U, and a link 42f,
 which connects third node R to sixth node W. Both the link 42e and the
 link 42f preferably incorporate the half-wavelength design.
 Note also that a half-wavelength separation of die blocks is also
 implemented on the output microstrip transmission line 43 of the die
 blocks 30a-30f. Thus, the preferred length of the output microstrip
 transmission line 43, which is maintained between the output connections
 33 of the die blocks 30a-30f as shown in FIG. 5, is a full wavelength of
 the operational wavelength of the device. Furthermore, the output pin 41
 connects to the output microstrip transmission line 43 where the output
 microstrip transmission line 43 intersects with the output connections 33
 of the fifth die block 30e and the sixth die block 30f.
 Thus, the present invention separates die blocks into a plurality of rows
 and a plurality of columns. Arranging die blocks in a plurality of rows
 and columns allows for an increased die spacing. The increased die spacing
 provides the ability to place more die on a fixed flange area (thus, more
 powerful devices for a fixed flange size), and for better heat spreading.
 Furthermore, in one embodiment, die blocks are connected by a conductor
 having a length which is preferably equal to one half of the operating
 wavelength of the circuit. The half wavelength separation of the die
 blocks provides for a push-pull amplifier effect. In addition, a Wilkinson
 hybrid on the device input and the half wavelength separation of die
 blocks make easier the matching of the device impedance to the impedance
 of the remainder of the circuit.
 While the invention has been described in conjunction with preferred
 embodiments, it should be understood that modifications will become
 apparent to those of ordinary skill in the art and that such modifications
 are therein to be included within the scope of the invention and the
 following claims.