RF Power Transistor
A semiconductor device including an RF power transistor in a semiconductor package is described. The semiconductor device comprises a gate lead frame, a drain lead frame, a die including a power transistor having a gate and a drain and a flange. A gate impedance matching network is connected between the gate lead frame and the gate. A drain impedance matching network is connected between the drain lead frame and the drain and includes a drain lead frame bond wire between the drain lead frame and the drain. A first conducting element is connected between the die and the flange and is arranged to provide a current path along which a return current can flow in use to lower an inductance associated with the drain lead frame bond wire.
1 . A semiconductor device comprising an RF power transistor in a semiconductor package, comprising:
a gate lead frame;
a drain lead frame;
a die including an RF power transistor having a gate and a drain;
a flange;
a gate impedance matching network connected between the gate lead frame and the gate; and
a drain impedance matching network connected between the drain lead frame and the drain, the drain impedance matching network including a drain lead frame bond wire between the drain lead frame and the drain, and a first conducting element electrically connected at both a first end and a second end to the flange and arranged to provide a current path along which a return current can flow in use to lower an inductance associated with the drain lead frame bond wire.
2 . The semiconductor device of claim 1 , wherein the first conducting element includes a first portion and the drain lead frame bond wire includes a first portion and the first portion of the first conducting element is arranged adjacent and parallel to the first portion of the drain lead frame bond wire.
3 . The semiconductor device of claim 1 , wherein the first end of the first conducting element is electrically connected to the flange through the die.
4 . The semiconductor device of claim 3 , wherein the RF power transistor is an LDMOS transistor which includes a source metal shield and wherein the first end of the first conducting element is electrically connected to the source metal shield.
5 . The semiconductor device of claim 1 , wherein the drain impedance matching network includes a first capacitor and a drain bond wire connected between the drain and the first capacitor and wherein the first conducting element is further arranged with a portion of the first conducting element overlapping with a portion of the drain bond wire and providing a current path along which a return current can flow in use to lower a mutual inductance associated with the drain bond wire and drain lead frame bond wire.
6 . The semiconductor device of claim 1 , wherein the first conducting element is arranged between the drain lead frame bond wire and the flange.
7 . The semiconductor device of claim 1 , and including a plurality of drain lead frame bond wires and a plurality of first conducting elements and wherein each first conducting element is positioned between a respective one of the plurality of drain lead frame bond wires and the flange.
8 . The semiconductor device of claim 1 , wherein the gate impedance matching network includes a second capacitor, a gate lead frame bond wire connected between the gate lead and the second capacitor, and a second conducting element electrically connected at a first end and a second end to the flange to provide a current path along which a return current can flow in use to lower an inductance associated with the gate lead frame bond wire.
9 . The semiconductor device of claim 8 , wherein the second conducting element includes a first portion and the gate lead frame bond wire includes a first portion and the first portion of the second conducting element is arranged adjacent and parallel to the first portion of the gate lead frame bond wire.
10 . The semiconductor device of claim 1 , wherein the first conducting element and drain lead frame bond wire form a loop having an area less than an area of a loop formed by the drain lead frame bond wire and the flange and/or wherein the second conducting element and the gate lead frame bond wire from a loop having an area less than an area of a loop formed by the gate lead frame bond wire and the flange.
11 . The semiconductor device of claim 8 , wherein the first end of the second conducting element is electrically connected to the flange through the second capacitor.
12 . The semiconductor device of claim 11 , wherein the second capacitor includes a lower plate electrically connected to the flange and wherein the first end of the second conducting element is electrically connected to the lower plate of the second capacitor.
13 . The semiconductor device of claim 8 , and including a plurality of gate lead frame bond wires and a plurality of second conducting elements and wherein each second conducting element is positioned between a respective one of the plurality of gate lead frame bond wires and the flange.
14 . An RF power amplifier including the semiconductor device of claim 1 .
15 . A telecommunications base station including the RF power amplifier of claim 14 .