A list of common RF components and elements are discussed. This is intended as a RF system overview for system engineers.
Imaging Rejection: A image of incoming RF signal is created after the mixer stage. This image signal is unwanted and needs to be rejected/filtered out before subsequent RF chain.
Preselector Filter: It's a filter (mostly made of bandpass) found between antenna and mixer to reject unwanted RF interference (i.e out of band signals)
Intermediate Frequency (IF): This is the stage immediately after mixer stage where RF signal is down-converted to a intermediate frequency that is not analog baseband (i.e low bandwidth signal)
Direct Conversion: This is a commonly used technique to directly cover RF signal down to analog baseband without an intermediate frequency stage. This process essentially removes Imaging rejection, hence no additional preselection filter is needed
Direct Radio Frequency Conversion: This is a modern receiver technique where using an ultra fast sampling rate ADC to sample RF signals into digital domain and uses digital signal processing for demodulation. This process is done inside the MODEM chip.
Filter: It allows only specific range of signal frequency to go through.
- Low Pass Filter
- High Pass Filter
- Band Pass Filter
- Surface Acoustic Wave (SAW) Filter
Diplexer: It separates RF signal based on frequency spectrum.
Duplexer: It separates RF signal based on signal direction
RF switch: It controls direction of RF signal path.
Matching Network: It's a impedance transformer made of capacitors and inductors for maximizing power transfer.
Attenuator: It's used to attenuate signal levels without causing unwanted signal reflection.
Power Amplifier (PA)
Low Noise Amplifier (LNA)
Modem: It modulates and demodulates RF signals.
Baseband processor: It processes premodulated or demodulated RF signals for transmission or reception respectively.
Network processor: It processed the chosen networking standard such as protocols and policies.