Hi,
We tested our DAC - DAC38j82 for the frequency range of 20 - 500 MHz, two tones are provided with 1MHz spacing. We have not achieved the specified results as per datasheet.
Test Condition : Fdac - 1200 MSPS , Interpolation - 2x and PLL - ON IoutFS -20 mA , @-6dBFs.
| Direct DAC Output | |||||||||
| S.No | F1 (MHz) | F2 (MHz) | 2F1-F2(MHz) | 2F2-F1(MHZ) | P1 (dBm) | P2 (dBm) | TOI P1 (dBc) | TOI P2 (dBc) | |
| 1 | 21 | 22 | 20 | 23 | -8.34 | -8.35 | -86.19 | -96.65 | |
| 2 | 30 | 31 | 29 | 32 | -8.32 | -8.32 | -83.97 | -93.84 | |
| 3 | 40 | 41 | 39 | 42 | -8.24 | -8.24 | -82.21 | -93.9 | |
| 4 | 50 | 51 | 49 | 52 | -8.2 | -8.21 | -80.37 | -88.58 | |
| 5 | 60 | 61 | 59 | 62 | -8.23 | -8.23 | -79.57 | -88.53 | |
| 6 | 70 | 71 | 69 | 72 | -8.19 | -8.18 | -76.8 | -87.7 | |
| 7 | 80 | 81 | 79 | 82 | -8.13 | -8.13 | -75.23 | -82.35 | |
| 8 | 90 | 91 | 89 | 92 | -8.11 | -8.12 | -74.1 | -81.4 | |
| 9 | 98 | 99 | 97 | 100 | -8.12 | -8.13 | -73.6 | -81.8 | |
| 10 | 101 | 102 | 100 | 103 | -8.13 | -8.13 | -73.2 | -80.7 | |
| 11 | 150 | 151 | 149 | 152 | -8.21 | -8.21 | -69.8 | -75.2 | |
| 12 | 200 | 201 | 199 | 202 | -8.31 | -8.32 | -66.15 | -74.18 | |
| 13 | 250 | 251 | 249 | 252 | -8.49 | -8.49 | -62.38 | -77.16 | |
| 14 | 300 | 301 | 299 | 302 | -8.654 | -8.63 | -59.9 | -91.03 | |
| 15 | 350 | 351 | 349 | 352 | -8.88 | -8.89 | -58.14 | -84.17 | |
| 16 | 400 | 401 | 399 | 402 | -9.09 | -9.102 | -57.71 | -70.86 | |
| 17 | 450 | 451 | 449 | 452 | -9.052 | -9.051 | -55.38 | -70.95 | |
| 18 | 498 | 499 | 497 | 500 | -9.342 | -9.36 | -54.18 | -67.19 | |
Is there anything to be look for in DAC settings?
Regards
Balaji.
