RF Characteristic Measurement The EPC8000 series come in chip-scale packages (shown in Figure 1) which was not designed with RF type connections. This means an RF connection must be constructed which can be used in subsequent amplifier designs. For the EPC8000 series devices, the design of the RF interface is based on micro strip lines [1] that taper towards the device and measurement is taken from reference planes that interface to a 50 Ω transmission line as shown in Figure 2.
Figure 1: Photograph of an EPC8000 series eGaN FET.
Due to thermal limitations, and since the device needs to be biased, pulse based testing was implemented to keep the average power dissipation of the device well below the thermal limit. In this case a 240 µs pulse was applied at a repetition rate of 10 Hz and was implemented using a specially designed controller [4] that ensured that the device remained stable and correctly biased under all test conditions. The design of the bias Tees for the amplifier must also accommodate pulse testing to ensure stable operation [5]. Class A Amplifier Design The s-parameters for all the EPC8000 series devices were measured and analyzed [6,7,8, and 9].
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Figure 2: Reference plane design for RF connection to the EPC8000 series FET.