High-frequency power amplifier
In a high-frequency power amplifier, gate feed portions are formed by dividing a gate feed which connects transistor gate electrodes in parallel, and each of the gate feed portions includes a given number of gate electrodes connected in parallel. Each of transistor cell elements includes a set of the gate electrodes connected in parallel. A resistance wire is interposed between the transistor cell elements to isolate each transistor cell element. The resistance wire and the gate electrodes are made of the same metal material and formed by the same process. Thus, closed loop oscillation of transistors is suppressed with no increase in chip size.
1. A power amplifier comprising:
a semiconductor substrate; and
a plurality of field effect transistors on the semiconductor substrate and electrically connected in parallel, each field effect transistor including
a plurality of interdigitated source, gate, and drain electrodes,
a plurality of transistor cell elements electrically connected in parallel, each transistor cell element having
a fixed number of the gate electrodes of the transistor,
a gate power supply segment electrically connecting in parallel the fixed number of gate electrodes of the transistor cell element, and
a gate power supply portion supplying a gate signal to the gate power supply segment of the transistor cell element, and
a resistance interconnect line having a resistance and interposed between and electrically connecting respective transistor cell elements of the transistor to each other.
2. The power amplifier according to claim 1 , wherein the resistance interconnect line and the gate electrodes of the transistors are the same metal material.
3. The power amplifier according to claim 1 , wherein the resistance interconnect line is part of an isolation resistor circuit connected between the respective gate power supply segments of the transistors.
4. The power amplifier according to claim 1 , wherein the resistance interconnect line is connected between leads of the gate power supply portions of the transistors.
5. The power amplifier according to claim 1 , wherein the resistance interconnect line is interposed between opposite ends of adjacent gate power supply segments and parallel to the gate electrodes, and the opposite ends of adjacent gate power supply segments are connected via the resistance interconnect line.
6. The power amplifier according to claim 5 , wherein the resistance interconnect line comprises a pair of parallel resistive interconnect lines between the opposite ends of adjacent gate power supply segments, and ends of the pair of parallel resistive interconnect lines are connected to each other.
7. The power amplifier according to claim 6 , including an ion-implanted insulating high-resistance region in a region of the semiconductor substrate between the pair of the parallel resistive interconnect lines which are located between the opposite ends of adjacent gate power supply segments.
8. The power amplifier according to claim 1 , wherein the resistance interconnect line interposed between the transistor cell elements comprises an extended portion of the gate power supply portion, and the gate power supply segments are connected to each other via the extended portion.
9. The power amplifier according to claim 1 , wherein the resistance interconnect line interposed between the transistor cell elements connected to adjacent gate power supply portions of the transistors, and the gate power supply segments are indirectly connected to each other via the resistance interconnect line.