An RF power amplifier is a type of electronic amplifier used to convert a low-power radio-frequency signal into a larger signal of significant power, typically for driving the antenna of a transmitter. It is usually optimized to have high efficiency and high output power, while minimizing heat dissipation. The basic RF amplifier apparatus includes an input circuit, a splitter, a final stage and a combiner that operate together to deliver the amplified output.
Existing RF amplifiers have problems. The RF amplifier assembly described above is difficult to manufacture, involves multiple assembly steps, and the assembly process is error prone. For example, each of the input signal circuit, splitter, modules of the final stage and combiner can be assembled on different printed circuit boards (PCBs). As such, wiring has to connect the circuitry together for the amplifier to operate. The circuitry and wiring of the RF amplifier can generate EMI that can affect the operation of the various electronic components of the circuit. Accordingly, the circuitry and wiring must be shielded and laid out on the circuit board in such a way so as to reduce RF and spurious emissions. Traditionally, this wiring is shielded by using a sheathed cabling to connect the various electronic components. However, the use of cabling creates significant routing and assembly issues and is difficult to implement. For example, the cabling can make the various solder connections difficult and time-consuming to implement. Moreover, the cabling and layout of the cabling for the traditional power amplifier has the potential to increase power losses on the wiring, reducing the overall efficiency of the power amplifier.
In addition to the wiring issues, a heat sink must also be provided in the amplifier to dissipate the heat generated by the electronic components and wiring. The heat sink must be disposed to maximize the dissipation of heat generated by the electronics, while exposing the electronic components so that they can also receive EMI shielding. To do this, multiple layers are used to provide the heat sink and EMI shield. Because the devices can be highly irregular, each electronic component could have its own heat sink, printed circuit board and EMI shield, increasing the number of components in the assembly, and creating more wiring issues.
Embodiments of the present invention attempt to resolve these issues and issues relating to combiners for RF power amplifiers.