High frequency amplifier apparatuses

Abstract

The invention relates to high-frequency amplifier apparatuses suitable for generating power outputs of at least 1 kW at frequencies of at least 2 MHz. The apparatuses include two LDMOS transistors each connected by their source connection to ground. The transistors can have the same design and can be arranged in an assembly (package). The apparatus also includes a circuit board lying against a cooling plate, which can be connected to ground, and the assembly is arranged on or against the circuit board. The apparatuses have a power transformer, whose primary winding is connected to the drain connections of the transistors, and a signal transmitter. A secondary winding of the signal transmitter can be connected to the gate connections of the two transistors. Each of the gate connections can be connected to ground via at least one voltage-limiting structural element.

What is claimed is: 
     
         1 . A high-frequency amplifier apparatus suitable for generating power for plasma excitation, the apparatus comprising:
 two Laterally Diffused Metal Oxide Semiconductor (LDMOS) transistors each having a drain terminal and a source terminal that is connected to a ground connection point, wherein the LDMOS transistors are embodied alike and are arranged as a package;   a circuit board that lies on a metal cooling plate, wherein the package is arranged on the circuit board;   a power transformer including a primary winding connected to the drain terminals of the two LDMOS transistors; and   a signal transformer including a secondary winding having a first end and a second end, wherein
 the secondary winding is connected at the first end to a first gate terminal of one of the two LDMOS transistors by one or more first resistive elements, and 
 the secondary winding is connected at the second end to a second gate terminal of the other of the two LDMOS transistors by one or more second resistive elements, 
   wherein each of the first gate terminal and second gate terminal is connected to ground by one or more voltage-limiters,   and wherein at least one of the voltage-limiters comprises at least one diode.   
     
     
         2 . The apparatus of  claim 1 , wherein the at least one diode has a cathode and an anode, wherein the cathode is arranged on a gate side and the anode is arranged on a ground side, wherein the gate side includes the first gate terminal and the second gate terminal, and the ground side includes at least one of the ground connections. 
     
     
         3 . The apparatus of  claim 1 , wherein at least one of the voltage-limiters comprises a plurality of diodes connected in series. 
     
     
         4 . The apparatus of  claim 3 , wherein the plurality of diodes comprise at least two diodes of different types. 
     
     
         5 . The apparatus of  claim 3 , wherein at least one of the plurality of diodes has a reverse recovery time that is less than a quarter of a cycle duration of a driving frequency of the two LDMOS transistors. 
     
     
         6 . The apparatus of  claim 1 , wherein the at least one diode is connected to one resistor in series. 
     
     
         7 . The apparatus of  claim 1 , wherein the first gate terminal and the second gate terminal are connected by one or more resistors to a DC voltage source. 
     
     
         8 . The apparatus of  claim 7 , wherein the one or more resistors are connected to a common capacitor. 
     
     
         9 . The apparatus of  claim 8 , wherein the common capacitor is connected to the DC voltage source, and is configured to discharge a gate capacitance. 
     
     
         10 . The apparatus of  claim 1 , wherein the power transformer is arranged on the circuit board and the primary winding is formed in a planar manner on the circuit board. 
     
     
         11 . The apparatus of  claim 1 , wherein the package has terminals that are contacted on the circuit board. 
     
     
         12 . A high-frequency amplifier apparatus suitable for generating power for plasma excitation, the apparatus comprising:
 two Laterally Diffused Metal Oxide Semiconductor (LDMOS) transistors each having a drain terminal and a source terminal that is connected to a ground connection point, wherein the LDMOS transistors are embodied alike and are arranged as a package;   a circuit board that lies on a cooling plate, wherein the package is arranged on the circuit board;   a power transformer including a primary winding connected to the drain terminals of the two LDMOS transistors; and   a signal transformer including a secondary winding having a first end and a second end, wherein
 the secondary winding is connected at the first end to a first gate terminal of one of the two LDMOS transistors by one or more first resistive elements, and 
 the secondary winding is connected at the second end to a second gate terminal of the other of the two LDMOS transistors by one or more second resistive elements, 
   wherein each of the first gate terminal and second gate terminal is connected to ground by one or more voltage-limiters, and   wherein the package is arranged on a substrate, in a housing, or both in a housing and on a substrate.   
     
     
         13 . The apparatus of  claim 12 , wherein the housing of the package is arranged in a cut-out in the circuit board. 
     
     
         14 . The apparatus of  claim 13 , wherein the package is mounted on a copper plate, and the copper plate and the package are arranged in the cut-out in the circuit board. 
     
     
         15 . The apparatus of  claim 14 , wherein the cut-out is stepped to be matched to surfaces of the copper plate and the package. 
     
     
         16 . The apparatus of  claim 12 , wherein the substrate includes a copper plate, and the package is mounted on the copper plate. 
     
     
         17 . The apparatus of  claim 16 , wherein the copper plate has a surface on which the package is mounted, wherein the surface is larger than a surface of the package that faces the cooling plate. 
     
     
         18 . A high-frequency amplifier apparatus suitable for generating power for plasma excitation, the apparatus comprising:
 two Laterally Diffused Metal Oxide Semiconductor (LDMOS) transistors each having a drain terminal and a source terminal that is connected to a ground connection point, wherein the LDMOS transistors are embodied alike and are arranged as a package;   a circuit board that lies on a cooling plate, wherein the package is arranged on the circuit board;   a power transformer including a primary winding connected to the drain terminals of the two LDMOS transistors; and   a signal transformer including a secondary winding having a first end and a second end, wherein
 the secondary winding is connected at the first end to a first gate terminal of one of the two LDMOS transistors by one or more first resistive elements, and 
 the secondary winding is connected at the second end to a second gate terminal of the other of the two LDMOS transistors by one or more second resistive elements; and 
   wherein each of the first gate terminal and second gate terminal is connected to ground by one or more voltage-limiters, and   wherein the circuit board is a multi-layered circuit board.   
     
     
         19 . The apparatus of  claim 18 , wherein the circuit board has at least one inner layer. 
     
     
         20 . The apparatus of  claim 18 , wherein the circuit board has four total layers.