Example Receiver Design with Zynq UltraScale+ RFSoC DFE

Co-location Deployment Considerations for Direct RF Sampling Transceivers (WP541)

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In this receiver design example, standard catalog components are used with the Zynq UltraScale+ RFSoC DFE to achieve the design targets outlined in the following table for the C-band co-location deployment. A detailed analysis for each filter is provided in this section. Co-location deployments with other bands can be similarly analyzed.

Table 1. C-Band Receiver Design Target Specification
Design Parameter Specification Notes
Operating band C-band
Co-locating band 1900M PCS / n2 band
Receiver NF ≤ 2.5 dB ~ 3.4 dB better than 3GPP reference sensitivity specification.
Equivalent reference sensitivity for 100 MHz NR carrier, i.e., minimum wanted signal –99 dBm [REF 1] 3GPP reference sensitivity specification is –95.6 dBm for 100 MHz carrier, which is equivalent to a 5.9 dB NF receiver. 95% throughput is equivalent to –1 dB SNR. A 2.5 dB NF receiver is 3.4 dB better than the 3GPP specification.
PCS band blocker signal level 16 dBm CW
RX NF desensitization due to blocker ~ 0.1 dB 3GPP specification allows 6 dB of desensitization. However, in practice, no desensitization is desirable. Consequently, the design target is to reduce any in-band interference due to the blocker to 10 dB below the wanted signal level.
Final in-band signal to interference ratio (SIR) due to blocker 10 dB
Maximum allowed interference from blocker that fall in-band, referenced to antenna input –109 dBm

In summary, the receiver must be able to receive a –99 dBm NR100 MHz signal in the presence of a 16 dBm CW blocker in the PCS band. As such, any in-band interference created by the blocker must be at –109 dBm or less for a SIR of 10 dB or better.

Note: This target of –99 dBm for the wanted signal is 9.4 dB (6 dB for desensitization allowance, 3.4 dB for better ref sensitivity) better than the 3GPP specification.

If the blocker aliases directly onto the wanted C-band, then the total analog filtering rejection needed at 1900 MHz is 16 – (–109) = 125 dB. If the blocker does not alias directly onto the C-band, less rejection is required. In the following example design, both scenarios are examined and the best way to distribute the filtering along the RF lineup is assessed.

Figure 1. Receiver Lineup Design Example

The receiver lineup in this figure shows an example design using standard catalog components that can be used to meet the target requirements listed in the table above. The antenna filter is typically a custom part for mMIMO systems as the size and mechanical fitting is very specific to the design, and, as such, no specific part is indicated.