Function of Component

The power amplifier will be used for the HackRF One transceiver. It’ll be used to amplify the 32 mW (15 dbm) received from the HackRF One transceiver to ~60 W. Or the internal power amplifier in the HackRF One could be bypassed to output 0 dBm instead.

Key Parameters

The following parameters were used in making a selection:

• Gain

  • How much the input signal is amplified by.
  • Formula for converting from mW or W to dB:

  

  • Units: dB (decibel)

• Operating Frequency

  • The frequency the power amplifier operates at.
  • Units: MHz (megahertz)

• Output Power

  • How much power the amplifier can output. This can be stated using parameters such as saturated output power or output power at 1 dB compression (P1dB).
  • Saturated Output Power: the amplifier will not be able to provide past this value when it’s saturated, regardless of the level of the input.
  • Power at 1 dB compression (P1dB): this is the input power level that causes the gain to decrease by 1 dB from its constant value. When this level is reached, the amplifier is no longer a linear device causing it to produce distortion, harmonics, and intermodulation products which will worsen the system bit error rate. Operating below this level is a must.
  • Units: W (watts) or dB (decibel)

• Impedance

  • Resistance against alternating current.
  • Units: Ohms

• Noise Figure

  • Value that describes the level of noise in a circuit. When a signal passes through a component, the degradation a component has on the Signal to Noise Ratio (SNR) can be determined from the noise figure.
  • An ideal value to aim for is as close to 0 dB (no noise) as possible.
  • Units: dB (decibel)

• Third Order Intercept (IP3):

  • How high of a signal the amplifier is able to process before intermodulation distortion occurs.
  • Describes the amount of intermodulation distortion (IMD) occurring and how linear a device is.
  • A device that has good linearity will have a high IP3. If the IP3 value is low, it is possible that the fundamental signal will be interfered by the intermodulation products.
  • Units: dBm (decibel-milliwatts)

Selection Criteria

Values being considered for the HackRF One Power Amplifier:

• Amplifier output should be 60W. If the HackRF One output is 0 dBm, the gain for the PA should be:

  10 log (60000 mW/ 1 mW) = approximately 48 dB

  OR If the HackRF One output is 15 dBm, the gain should be:

  10 log (60000 mW/ 32 mW) = approximately 33 dB

  May use a pre-amplifier to increase the input power to between 1-5 W (30-37 dBm). If so, the gain will be 18 dB for an input power of 1 W or between 11 dB for an input power of 5 W:

  10 log (60000 mW / 1000 mW) = approximately 18 dB

  10 log (60000 mW / 5000 mW) = approximately 11 dB

• P1dB:

  • For an input of 1mW, P1dB should be higher than 0 dBm
  • For an input of 32mW, P1dB should be higher than 15 dBm
  • For an input of 1W, P1dB should be higher than 30 dBm
  • For an input of 5W, P1dB should be higher than 37 dBm

• Operating frequency should be around 430-450 MHz

• Impedance should be 50 ohms

• Noise figure should be ideally as close to 0 dB as possible

• The higher the IP3 value, the better

Options

The options will be found in the Ground Station Power Amplifier Sheet.