380MHz linear amplifier circuit composed of RF2175

As shown in the figure, this is a 380MHz linear amplifier application circuit composed of RF2175. The RF signal (RF) is input from pin 6, and is amplified by the preamplifier and the final power amplifier and output from pins 12 and 13. Pin 6 is directly coupled to the internal amplifier, so an external DC-blocking coupling capacitor is added. The output pins 12, 13 and 14 are connected inside the chip, and usually pins 12 and 13 are connected together externally as signal output. Pins 12 and 13 are also used as the power supply terminals of the final power amplifier, and bias current is provided to the final power amplifier through these pins. Pin 14 is used as a second harmonic filter circuit, using transmission lines or inductors and capacitors to form a filter resonant at 2f0, providing a low-impedance path for the second harmonic, which can effectively short the second harmonic. Pin 8 is connected to the enable voltage VREG, which can control the voltage of this pin and thus control the power supply power. When the voltage is low, the amplifier power supply is in the off state; when the voltage is high (2.8V), the amplifier power supply is in the standard working state. Pin 8 is connected to an external 100pF high frequency filter capacitor. Pin 16 is connected to VBIAS, which controls the efficiency of the circuit in low power mode. When working at full power, this pin should be set to 2.8V.