Sequence of acquisiition of the SYSREP_POS without changing SYSREF_SEL (SYSREF_SEL = 0) Sampling frequency 2 Gs/s, ADC clock frequency 1 GHz Four different ADCs are used. First column: number of acquisition second to fifth column: SYSREF_POS values for ADC#0 to ADC#3 Each row reports one acquisition, the procedure to acquire is as follows: 1 - Write SYSREF_SEL = 0 il all the ADCs 2 - Apply 10 rising edges of SYSREF 3 - Read SYSREF_POS from alla ADCs and report the values in the row 1 4 - Apply 10 rising edges of SYSREF 5 - Read SYSREF_POS from alla ADCs and report the values in the row 2 Repeat step 4 and 5 until the row 50. ADC#0 ADC#1 ADC#2 ADC#3 # 76543210FEDCBA9876543210 76543210FEDCBA9876543210 76543210FEDCBA9876543210 76543210FEDCBA9876543210 1 110000000000001100000001 100000000000011000000001 100000001100000000000011 110000000000000110000001 2 100000000000011000000001 100000000000110000000001 100000001100000000000011 100000000000001100000001 3 100000000000011000000001 100000000000110000000001 100000001100000000000011 100000000000001100000001 4 110000000000001100000001 100000000000011000000001 100000000110000000000001 110000000000000110000001 5 110000000000001100000001 100000000000011000000001 100000000011000000000001 110000000000000110000001 6 110000000000001100000001 100000000000011000000001 100000000110000000000001 110000000000000110000001 7 110000000000001100000001 100000000000011000000001 100000000011000000000001 110000000000000110000001 8 100000000000011000000001 100000000000110000000001 100000001100000000000011 100000000000001100000001 9 110000000000001100000001 100000000000011000000001 100000001100000000000001 110000000000000110000001 10 110000000000001100000001 100000000000011000000001 100000001100000000000011 110000000000001100000001 11 100000000000011000000001 100000000001100000000001 100000001100000000000011 100000000000001100000001 12 111000000000000110000001 100000000000001100000001 100000000011000000000001 111000000000000011000001 13 100000000000110000000001 100000000001100000000001 100000001100000000000011 100000000000011000000001 14 110000000000001100000001 100000000000011000000001 100000000110000000000001 110000000000000110000001 15 110000000000001100000001 100000000000011000000001 100000001100000000000001 110000000000001100000001 16 111000000000000110000001 100000000000001100000001 100000000110000000000001 111000000000000110000001 17 110000000000001100000001 100000000000110000000001 100000001100000000000001 100000000000001100000001 18 110000000000001100000001 100000000000011000000001 100000000110000000000001 110000000000000110000001 19 100000000000110000000001 100000000001100000000001 100000000110000000000001 100000000000011000000001 20 111000000000001100000001 100000000000001100000001 100000000110000000000001 110000000000000110000001 21 100000000000110000000001 100000000001100000000001 100000011000000000000011 100000000000011000000001 22 110000000000001100000001 100000000000011000000001 100000000011000000000001 110000000000000110000001 23 100000000000011000000001 100000000000110000000001 100000001100000000000011 100000000000001100000001 24 110000000000001100000001 100000000000011000000001 100000000011000000000001 110000000000000110000001 25 100000000001100000000001 100000000011000000000001 100000011000000000000111 100000000000011000000001 26 100000000000011000000001 100000000000110000000001 100000001100000000000011 100000000000001100000001 27 100000000000011000000001 100000000000110000000001 100000001100000000000001 100000000000001100000001 28 110000000000001100000001 100000000000011000000001 100000001100000000000001 110000000000000110000001 29 100000000000110000000001 100000000001100000000001 100000001100000000000011 100000000000001100000001 30 110000000000001100000001 100000000000011000000001 100000000011000000000001 110000000000000110000001 31 111000000000000110000001 100000000000001100000001 100000000011000000000001 111000000000000011000001 32 100000000000011000000001 100000000000110000000001 100000001100000000000011 100000000000001100000001 33 111000000000000110000001 100000000000001100000001 100000000110000000000001 111000000000000110000001 34 110000000000001100000001 100000000000011000000001 100000000110000000000001 110000000000000110000001 35 111000000000000110000001 100000000000001100000001 100000000110000000000001 111000000000000110000001 36 110000000000001100000001 100000000000011000000001 100000000110000000000001 110000000000000110000001 37 110000000000001100000001 100000000000011000000001 100000000110000000000001 110000000000000110000001 38 111000000000001100000001 100000000000011000000001 100000000011000000000001 110000000000000110000001 39 110000000000001100000001 100000000000011000000001 100000000110000000000001 110000000000000110000001 40 100000000000011000000001 100000000000110000000001 100000001100000000000011 100000000000001100000001 41 100000000000011000000001 100000000000110000000001 100000001100000000000011 100000000000001100000001 42 100000000000011000000001 100000000000110000000001 100000001100000000000011 100000000000001100000001 43 110000000000001100000001 100000000000011000000001 100000000110000000000001 110000000000000110000001 44 110000000000001100000001 100000000000011000000001 100000000110000000000001 110000000000000110000001 45 110000000000001100000001 100000000000011000000001 100000000110000000000001 110000000000000110000001 46 111000000000001100000001 100000000000001100000001 100000000110000000000001 110000000000000110000001 47 111000000000000110000001 100000000000001100000001 100000000110000000000001 111000000000000110000001 48 100000000001100000000001 100000000011000000000001 100000011000000000000111 100000000000110000000001 49 111000000000000110000001 100000000000001100000001 100000000110000000000001 110000000000000110000001 50 100000000000110000000001 100000000001100000000001 100000011000000000000011 100000000000011000000001 76543210FEDCBA9876543210 76543210FEDCBA9876543210 76543210FEDCBA9876543210 76543210FEDCBA9876543210 F |----| |----| |---| |----| The row "F" indicates the "Forbidden zone", thia appear to be too large to support a sampling frequency of 4 Gs/s. Some acquisitions 4 Gs/s was executd with the same procedure, tghe results are shown below: ADC#0 ADC#1 ADC#2 ADC#3 # 76543210FEDCBA9876543210 76543210FEDCBA9876543210 76543210FEDCBA9876543210 76543210FEDCBA9876543210 1 110000011000001100000111 101100000110000001100001 111000001100000110000011 100000110000001100000111 2 110000011000001100000111 111111000110000001100001 101100000110000011000001 100000110000001100000111 3 111000001100000110000011 100110000011000000110001 100110000011000001100001 110000011000001100000011 4 101100000110000011000001 100011000001100000011001 100011000001100000110001 110000001100000110000001 5 110000011000001100000111 101100000011000001100001 111000001100000011000001 100000110000001100000111 6 101100000110000011000001 100011000000110000011001 100110000001100000110001 111000001100000011000001 7 101100000110000011000001 100011000000110000011001 100011000001100000110001 111000001100000110000001 8 101100000110000011000001 100011000000110000011001 100011000001100000110001 111000001100000110000001 9 101100000110000011000001 100011000001100000011001 100110000011000001100001 110000001100000110000011 10 111000001100000110000011 100110000011000000110001 101100000011000001100001 100000011000001100000111 11 111000001100000110000011 100110000011000000110001 100110000011000001100001 110000011000001100000011 12 110000110000011000001101 111000000110000011000001 111000001100000110000011 100000110000011000001101 13 111000001100000110000011 100110000011000000110001 101100000110000011000001 100000011000001100000111 14 101100001100000110000011 100011000001100000011001 100110000011000001100001 110000001100000110000011 15 111000011000001100000011 101100000011000001100001 101100000110000011000001 100000011000001100000111 16 100000110000011000001101 111000001100000011000001 111000001100000110000011 100001100000011000001101 17 111000001100000110000011 100110000011000000110001 101100000110000011000001 100000011000001100000011 18 111000000000100010000011 100110000001100000110001 100110000011000001100001 110000011000000110000011 19 101100000110000011000001 100011000001100000011001 100110000011000001100001 110000001100000110000011 20 101100000110000011000001 100011000001100000011001 100110000011000001100001 110000001100000110000011 21 111000001100000110000011 100110000011000000110001 100110000011000001100001 100000011000001100000011 22 100001100000110000011001 110000001100000110000001 110000011000001100000111 100011000000110000011001 23 110000011000001100000111 101100000110000001100001 101100000110000011000001 100000110000001100000111 24 101100000110000011000001 100011000000110000011001 100110000011000001100001 111000001100000110000001 25 111000001100000110000011 100110000011000000110001 101100000110000011000001 110000011000001100000011 26 101100001100000110000011 100011000001100000110001 100011000001100000110001 110000001100000110000011 27 110000011000001100000111 101100000011000001100001 111000001100000011000001 100000110000001100000111 28 110000011000001100000111 101100000011000001100001 101100000110000011000001 100000011000001100000111 29 111000001100000110000011 101100000011000001100001 100110000011000001100001 100000011000001100000011 30 101100000110000011000001 100011000001100000011001 100110000011000001100001 110000001100000110000011 31 101100000110000011000001 100011000001100000011001 100110000011000001100001 110000001100000110000011 32 111000011000001100000011 101100000011000001100001 101100000110000011000001 100000011000001100000111 33 101100000110000011000001 100001100000110000001101 100011000001100000110001 111000001100000011000001 34 100110000011000001100001 100001100000110000001101 100011000001100000110001 111000000110000011000001 35 100000110000011000001101 111000000110000011000001 110000001100000110000011 100001100000011000001101 76543210FEDCBA9876543210 76543210FEDCBA9876543210 76543210FEDCBA9876543210 76543210FEDCBA9876543210 F |--------------| |----| |-----| |---| |----| |- --| |----| |--- Looking at the "Forbidden zone", we can note that: 1 - No valid position for SYSREF_SEL are available for ADC#0 2 - Very narrow zones are available for the other ADCs.