JAJSMY5 July 2024
ADVANCE INFORMATION
Select an RF DAC such as the DAC39RF10 for this application because the DAC supports sampling at 10GSPS and the required RF signal frequency range of 4GHz. The DAC39RF10 outputs a signal level of –0.4dBm at 2GHz when operated at –1dBFS. The TRF1108 has a gain of 15.5dB and OP1dB of 12dBm at 2GHz; therefore, add a 9.1dB attenuator pad at the output of the DAC to get 6dBm output power. A 5GHz low-pass filter can optionally be added to reject the DAC images in the second Nyquist zone. From the TRF1108 specifications, the device meets the design requirement of output return loss.
Table 7-2 shows the component values for attenuator and low-pass filter for the design.
SECTION | DESIGNATOR | TYPE | VALUE |
---|---|---|---|
Attenuator | R1 | Resistor | 24Ω |
Attenuator | R2 | Resistor | 80Ω |
Attenuator | R3 | Resistor | 24Ω |
Low-pass filter | C1 | Capacitor | 0.5pF |
Low-pass filter | C2 | Capacitor | 0.8pF |
Low-pass filter | C3 | Capacitor | 0.5pF |
Low-pass filter | L1 | Inductor | 2nH |
Low-pass filter | L2 | Inductor | 2nH |