Board features
The connections
Figure 1 - Card features
Features
| Parameter | Value |
|---|---|
| Max. Sampling rate | 125 MSPS |
| Bits/sample | 14 bit |
| ENOB (THD omitted) | 12.2 bit |
| ENOB at 15 MHz | 11.4 bit |
| Channels | 4 |
| Connectors | SMA @ 50 ohm |
| Input Range | +/- 1 V |
| Miscellaneous | GPIO connectors, temperature sensor, clock synchronized output |
| Clock source | Internal: 100 MHz oscillator |
| External: up to 125 MHz with an external clock |
Inputs
| Input | Connector | Max Voltage |
|---|---|---|
| Ground referenced analog signal | SMA | 2 Vpp |
| Differential analog signal | SMA | 2 V |
| Clock Input signal | SMA | 2 Vpp |
| MicroZed Board GPIO | Pin headers | 3.3 V |
| Buck switching frequency input | SMA | 5.5 V |
| 12 V power supply | Barrel DC jack & MINI DIN 4 | 16 V DC |
Measured ENOB
The measured ENOB (THD omitted) is 12.2 bit with a sampling frequency of 100 MHz (on board oscillator). This measurement has been done using the same method as for the FMC ADC 100M
It has also been measured at 15 MHz. The result is 11.4 bit. It was necessary to filter the output of the R&S oscillator to get these results.
Power requirements
This board is designed to work with a 12 V DC at 3 A max.
Using the local oscillator
By default, the board is mounted to be able to use an external oscillator (connector J13, 50 Ohm). To use the local oscillator, the ferrite bead L14 has to be mounted. The resistor R42 has to be removed and replaced by R33. The clock splitter LT6957 can also be used as a filter. Its cutting frequency can be set by the jumpers J15 and J16 (table 1), by default (without the jumpers), the bandwidth is set to 1200 MHz. The low position of the jumper is indicated by the 1 on the silkscreen. For example, if we want a bandwidth of 160 MHz, the jumper on J15 has to be placed linking the pin3 and the pin2 and J16 with the jumper linking the pin2 and pin1.
| J15 | J16 | Bandwidth |
|---|---|---|
| LOW | LOW | 1200 MHz (Full Bandwidth) |
| LOW | HIGH | 500 MHz (-3 dB) |
| HIGH | LOW | 160 MHz (-3 dB) |
| HIGH | HIGH | 50 MHz (-3 dB) |
Table 1 - LT6957 bandwith according to the jumper position
Changing the buck converter switching frequency
It is possible to change the LM43603 switching frequency. On one hand, it is possible to change it by replacing the R19 resistor (Table 2). By default, this frequency is set to around 1 MHz by the use of a 39k resistor. The Table 2 is used as information, any resistor value in between two values of the table will give a switching frequency in between the corresponding frequencies. If no resistor is connected, the switching frequency is 500 kHz.
On the other hand, it is possible to use an external oscillator to set this switching frequency. The clock signal is given on the J14 connector (50 Ohm). It is recommended to connect a resistor R19 such that the internal oscillator frequency is the same as the external one. More information on the LM43603 datasheet.
| Fs [kHz] | R19 [kOhm] |
|---|---|
| 200 | 200 |
| 350 | 115 |
| 500 | 78.7 |
| 750 | 53.6 |
| 1000 | 39.2 |
| 1500 | 26.1 |
| 2000 | 19.6 |
| 2200 | 17.8 |
Table 2 - LM43603 switching frequency according to the R19 resistor
Board GPIO connectors
Some GPIO pins are provided to be able to use the board for other purposes. While turning the card as on the above picture (Figure 1), the pin 1 for each connector is the one on the bottom left. Pin 2 is directly to its right etc. The pin 7 is placed above the pin1, next to it is the pin 8 etc. The table Table 3 shows the used GPIO.
| ADC board connection | MicroHeader Connection | Zynq AP SoC Connection |
|---|---|---|
| P2 pin 1 | pin 73 Bank 35 | K14 |
| P2 pin 2 | pin 75 Bank 35 | J14 |
| P2 pin 3 | pin 74 Bank 35 | H15 |
| P2 pin 4 | pin 76 Bank 35 | G15 |
| P2 pin 7 | pin 81 Bank 35 | N15 |
| P2 pin 8 | pin 83 Bank 35 | N16 |
| P2 pin 9 | pin 82 Bank 35 | L14 |
| P2 pin 10 | pin 84 Bank 35 | L15 |
| P3 pin 1 | pin 62 Bank 35 | F19 |
| P3 pin 2 | pin 64 Bank 35 | F20 |
| P3 pin 3 | pin 61 Bank 35 | G17 |
| P3 pin 4 | pin 63 Bank 35 | G18 |
| P3 pin 7 | pin 53 Bank 35 | H16 |
| P3 pin 8 | pin 55 Bank 35 | H17 |
| P3 pin 9 | pin 54 Bank 35 | J18 |
| P3 pin 10 | pin 56 Bank 35 | H18 |
| P4 pin 1 | pin 36 Bank 35 | M19 |
| P4 pin 2 | pin 38 Bank 35 | M20 |
| P4 pin 3 | pin 41 Bank 35 | M17 |
| P4 pin 4 | pin 43 Bank 35 | M18 |
| P4 pin 7 | pin 35 Bank 35 | L19 |
| P4 pin 8 | pin 37 Bank 35 | L20 |
| P4 pin 9 | pin 42 Bank 35 | K19 |
| P4 pin 10 | pin 44 Bank 35 | J19 |
| P5 pin 1 | pin 23 Bank 35 | E17 |
| P5 pin 2 | pin 25 Bank 35 | D18 |
| P5 pin 3 | pin 24 Bank 35 | D19 |
| P5 pin 4 | pin 26 Bank 35 | D20 |
| P5 pin 7 | pin 29 Bank 35 | E18 |
| P5 pin 8 | pin 31 Bank 35 | E19 |
| P5 pin 9 | pin 30 Bank 35 | F16 |
| P5 pin 10 | pin 32 Bank 35 | F17 |
Table 3 - GPIO connections to the Zynq
05th of December 2016 - Nicolas Boucquey