1.2 Receiver
(Ask a Question)High-speed data coming from transmitter, passing through a channel can result in degradation of the signals and making it difficult for the receiver to detect it correctly. As the data rate increases, equalization at the receiver becomes a necessity. Equalizers are used to compensate the high frequency losses included within the channel. Analog equalization is done by Continuous Time Linear Equalizers (CTLE) whereas discrete time equalization can be achieved by Decision Feedback Equalization (DFE). For lower data rates CTLE is sufficient, however, for higher data rate DFE is also used along with CTLE.
PolarFire Rx supports 85Ω, 100Ω and 150Ω terminations. The receiver provides three types of equalization:
- Clock and Data Recovery (CDR) Mode: This option provides users to apply any CTLE setting including the recommended (Default values in the Libero SoC) ones or settings obtained from the IBIS-AMI simulations.
- CDR Mode with Calibration: The device internal algorithm optimizes the receiver and applies the best CTLE settings in the device for the given channel and Tx attributes.
- DFE Mode: PolarFire transceiver consist of a five tap DFE engine. DFE is used when the data rate is high or loss of the channel is too high. DFE is always used along with CTLE. In CDR mode with calibration, the device optimizes the receiver and provides best CTLE and associated DFE coefficients. DFE in IBIS-AMI simulations is used only to sign-off the hardware.
63 CTLE settings are provided for receiver tuning. Libero SoC default CTLE settings are assigned for a particular data rate range and channel. However, other settings can also be used for the same range as shown in the following table.
| Insertion Loss | Data Rate (Mbps) | Mode | RX_CTLE Value |
|---|---|---|---|
| Short (6.5 dB) | 250–5000 | CDR | No Peak + 2.8 dB |
| 5000–6875 | CDR | 3 GHz + 1.4 dB | |
| 6875–8437.5 | CDR | 5 GHz + 1.8 dB | |
| 8437.5–10312.5 | CDR | 5 GHz + 7.3 dB | |
| 10312.5–12700 | DFE | 5 GHz + 10.6 dB | |
| Medium (17.0 dB) | 250–5000 | CDR | 3 Ghz + 5.5 dB |
| 5000–6875 | CDR | 3 GHz + 1.4 dB | |
| 6875–8437.5 | DFE | 5 GHz + 7.3 dB | |
| 8437.5–10312.5 | DFE | 5 GHz + 7 .3 dB | |
| 10312.5–12700 | DFE | 6 GHz + 11.1 dB | |
| Long (25.0 dB) | 250–5000 | CDR | 3 Ghz + 11.4 dB |
| 5000–6875 | CDR | 3 GHz + 6.8 dB | |
| 6875–8437.5 | DFE | 5 GHz + 7.3 dB | |
| 8437.5–10312.5 | DFE | 5 GHz + 7.3 dB | |
| 10312.5–12700 | DFE | 6 GHz + 11.1 dB |
The following table lists all 63 CTLE settings and the recommended data rate range in which they are used.
Important: You can set any settings for any data rate.
| Serial Number | RX_CTLE Settings | DC Gain (dB) | Peak AC Gain (dB) | Data Rate (Mbps) |
|---|---|---|---|---|
| 1 | No_Peak_ + 7.3 dB | 7.27 | 7.28 | 250–1600 |
| 2 | No_Peak_ + 9.3 dB | 9.28 | 9.29 | 250–1600 |
| 3 | No_Peak_ + 2.8 dB | 2.85 | 3.07 | 250–1600 |
| 4 | 3_Ghz_ + 5.5 dB | –2.28 | 3.17 | 250–1600 |
| 5 | 3_Ghz_ + 11.4 dB | –7.98 | 3.46 | 250–1600 |
| 6 | No_Peak_ + 2.82 dB | 2.82 | 2.84 | 250–1600 |
| 7 | No_Peak_ + 0.1 dB | 0.12 | 0.13 | 250–1600 |
| 8 | No_Peak_ – 2.5 dB | –2.57 | –2.48 | 250–1600 |
| 9 | No_Peak_ – 7.1 dB | –7.15 | –6.86 | 250–1600 |
| 10 | 3_GHz_ + 4.62 dB | –13.00 | –8.38 | 250–1600 |
| 11 | No_Peak_ + 4.6 dB | 4.61 | 4.62 | 250–1600 |
| 12 | No_Peak_+1.8 dB | 1.86 | 1.88 | 250–1600 |
| 13 | No_Peak_ – 0.9 dB | –0.94 | –0.87 | 250–1600 |
| 14 | No_Peak_ – 5.6 dB | –5.61 | –5.42 | 250–1600 |
| 15 | 3_GHz_ + 4.6 dB | –11.60 | –6.99 | 250–1600 |
| 16 | 3_GHz_ + 11.0 dB | –9.34 | 1.71 | > 1600–5000 |
| 17 | 3_GHz_ + 5.6 dB | –6.43 | –0.77 | > 1600–5000 |
| 18 | No_Peak_ – 1.1 dB | –1.17 | –0.62 | > 1600–5000 |
| 19 | 3_GHz_ + 12.3 dB | –12.77 | –0.44 | > 1600–5000 |
| 20 | 3_GHz_ + 2.3 dB | –6.48 | –4.18 | > 1600–5000 |
| 21 | 3_GHz_ + 9.0 dB | –12.96 | –3.90 | > 1600–5000 |
| 22 | 3_GHz_ + 5.9 dB | –5.02 | 0.90 | > 1600–5000 |
| 23 | No_Peak_ + 0.3 dB | 0.37 | 1.01 | > 1600–5000 |
| 24 | 3_GHz_ + 12.6 dB | –11.37 | 1.24 | > 1600–5000 |
| 25 | 3_GHz_ + 2.4 dB | –5.07 | –2.66 | >1600–5000 |
| 26 | 3_GHz_+ 9.1 dB | –11.54 | –2.37 | > 1600–5000 |
| 27 | 3_GHz_ + 1.4 dB | 4.55 | 5.96 | > 5000–6875 |
| 28 | 3_GHz_ + 6.8 dB | –2.32 | 4.53 | > 5000–6875 |
| 29 | 3_GHz_ + 12.9 dB | –8.07 | 4.88 | > 5000–6875 |
| 30 | 3_GHz_ + 7.8 dB | –5.11 | 2.70 | > 5000–6875 |
| 31 | 3_GHz_ + 2.2 dB | 0.29 | 2.57 | > 5000–6875 |
| 32 | 3_GHz_ + 14.5 dB | –11.50 | 3.05 | > 5000–6875 |
| 33 | 3_GHz_ + 4.8 dB | –5.16 | –0.29 | > 5000–6875 |
| 34 | 3_GHz_ + 11.8 dB | –11.67 | 0.17 | > 5000–6875 |
| 35 | 5_GHz_ + 1.8 dB | 4.56 | 6.36 | > 6875–8437.5 |
| 36 | 5_GHz_ + 7.3 dB | –2.30 | 5.03 | > 6875–8437.5 |
| 37 | 5_GHz_ + 13.4 dB | –8.07 | 5.38 | > 6875–8437.5 |
| 38 | 5_GHz_ + 8.4 dB | –5.11 | 3.33 | > 6875–8437.5 |
| 39 | 5_GHz_ + 2.8 dB | 0.30 | 3.14 | > 6875–8437.5 |
| 40 | 5_GHz_ + 15.1 dB | –11.50 | 3.68 | > 6875–8437.5 |
| 41 | 5_GHz_ + 5.7 dB | –5.16 | 0.58 | > 6875–8437.5 |
| 42 | 5_GHz_ + 12.7 dB | –11.70 | 1.09 | > 6875–8437.5 |
| 43 | 5_GHz_ + 9.8 dB | –5.43 | 4.40 | > 8437.5–10312.5 |
| 44 | 5_GHz_ + 12.4 dB | –8.09 | 4.35 | > 8437.5–10312.5 |
| 45 | 5_GHz_ + 9.6 dB | –5.40 | 4.22 | > 8437.5–10312.5 |
| 46 | 5_GHz_ + 10.6 dB | –5.38 | 5.20 | > 8437.5–10312.5 |
| 47 | 6_GHz_ + 11.1 dB | –4.34 | 6.79 | > 10312.5 |
| 48 | 6_GHz_ + 10.1 dB | –4.34 | 5.79 | > 10312.5 |
| 49 | 6_GHz_ + 10.13 dB | –4.18 | 5.95 | > 10312.5 |
| 50 | 6_GHz_ + 12.2 dB | -10.14 | 2.06 | > 10312.5 |
| 51 | 6_GHz_ + 11.0 dB | –6.82 | 4.24 | > 10312.5 |
| 52 | 6_GHz + 12.0 dB | –6.97 | 5.07 | > 10312.5 |
| 53 | 6_GHz_ + 11.5 dB | –7.25 | 4.28 | > 10312.5 |
| 54 | 6_GHz_ + 13.1 dB | –7.17 | 5.92 | > 10312.5 |
| 55 | No_Peak_ + 9.22 dB | 9.22 | 9.24 | > 8437.5–10312.5 |
| 56 | No_Peak_ + 4.53 dB | 4.53 | 4.55 | > 8437.5–10312.5 |
| 57 | No_Peak_ + 1.76 dB | 1.76 | 1.78 | > 8437.5–10312.5 |
| 58 | 5_GHz_ + 3.14 dB | –1.52 | 1.61 | > 8437.5–10312.5 |
| 59 | No_Peak_ + 11.10 dB | 11.10 | 11.13 | > 10312.5 |
| 60 | No_Peak_ + 6.13 dB | 6.13 | 6.15 | > 10312.5 |
| 61 | No_Peak_ + 3.39 dB | 3.39 | 3.41 | > 10312.5 |
| 62 | 6_GHz_ + 2.73 dB | 0.32 | 3.06 | > 10312.5 |
| 63 | 6_GHz_ + 3.12 dB | 1.50 | 4.62 | > 10312.5 |
For higher dates rate, five tap DFE is used along with CTLE. The following table lists the Libero SoC sets the default DFE and CTLE settings for given channel and data rate.
| Channel | Data Rate (Mbps) | Ctle Setting | DFE Coefficients |
|---|---|---|---|
| SHORT | 10312.5–12700 | 5_GHz_ + 10.6 dB | 6,–3,–2,–1,–1 |
| MEDIUM | 6875–8437.5 | 5_GHz_ + 7.3 dB | 7, 1, 2, 2, 0 |
| MEDIUM | 8437.5–10312.5 | 5_GHz_+ 7.3 dB | 8, –3, –2, –1, 0 |
| MEDIUM | 10312.5–12700 | 6_GHz_ + 11.1 dB | 10, 0, –2, –1, 0 |
| LONG | 6875–8437.5 | 5_GHz_ + 7.3 dB | 7, –1, 0, 0, 0 |
| LONG | 8437.5–10312.5 | 5_GHz_ + 7.3 dB | 8, –5, –1, –1, 0 |
| LONG | 10312.5–12700 | 6_GHz_ + 11.1 dB | 10, 1, 0, 0, 0 |
Important: These settings are used when auto calibration of DFE is not selected.