1. 5 Gsps ADC Developement and Future Collaboration
ASIAA, Institute of Astronomy and Astrophysics, Academia Sinica Taiwan
Homin Jiang, Chao-Te Li
CASPER Workshop 2009, Cape Town

2. Key Radio Projects
2 GHz bandwidth, going to be 4 GHz,digital correlator
16 GHz bandwidth, 2 channels analog correlator

3. We focus on wideband, coarse resolution correlator for imaging.
Casper majority focus on high resolution, narrow band spectroscopy.
So we need wide band ADC board.

4. Specification board size: 12.5 X 8.5 cm2 main chip: e2v EV8AQ160
sampling rate: 5GS/S, 8-bit
PCB stack: 8 layer
Input signals: 2 analog signals, 1 clock and
1 synchronization. All are SMA connectors.
output signals: 8-bit/4 channel/1.25Gsps high speed digital signals and SPI control bus. All signals connect to a main board via 2 Tyco ZDOK connectors.

5. 4 1.25Gsps interleaved.
2.5 GHz clock input.
2 GHz bandwidth

6. Component Side Solder Side Polypropylene Polypropylene Polypropylene
Layer
Description
P.P / Core / Copper
Thickness
mil (mm)
Tolerance
mil
Solder Mask
0.5
2nd Copper
1.0 1
Signal
0.5 oz Cu
0.6 A
Core
RO4003C
8.0 2
Ground B
P.P.
5.0 3
1.0 oz Cu
1.2 C
FR4 4
Power D
10.0 5 E 6 F 7 G 8
62.2 (1.580)
Target Thickness：
1.6mm ± 10% = [ 69 ~ 57 mils ]
Component Side 1
Core 1 / 1 oz 2
Polypropylene 3
Core 1 / 1 oz 4
Polypropylene 5
Core 1 / 1 oz 6
Polypropylene 7
Core 1 / 1 oz 8
Solder Side

7. 5 Gsps ADC Roger 4003 substrate on the top and bottom layer.
Differential pair of analog input

8. Test Before Roach

9. Serial Data
1.875GHz

10. Interface to ROACH ADC outputs 1.25Gsps data rate per channel.
Virtex-5 maximum speed is 550MHz. Can’t access directly.
Use serial-to-parallel device (SERDES) and ChipSync technology to slow down the data rate.
Use Virtex-5 evaluation board XUPV5-LX110T to implement 1 channel data receiver at 1.25Gsps because it has the same chip as the ROACH.
Received 100MHz data on Virtex-5 evaluation board with 1:8 deserialization factor

11. Current Status
Hardware is ready.
Working on ROACH: ISERDES and SPI

12. Collaboration 9(x2 ?) 28-baseline Correlators with 4-8 GHz bandwidth.
Preliminary Specification of Future SMA :
Frequency: 230/345 GHz
Bandwidth : 4-8 GHz
No. of Focal Plane Array: 9
Polarizations : 2
No. of Antenna : 8
Zoom in function A1 A2 A3 A4 A5 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 A6 C9 C1 C2
As you know, alma is going to finish in 4 to5 years. SMA people start to think about what SMA can do in post-alma. A7 1 2 3 4 5 6 7 8 9 A8

13. Material Cost Estimation
One ROACH = 5k US *, One 5 Gsps ADC = 1K US **, one 12 port 10G switch = 7.5k
8 GHz Bandwidth needs 4 ADC boards. 2 ROACHs.
Assume a switch for polarization swapping.
One correlator needs 32 ADCs, 16 ROACHs and 2 switches
9 sets of correlator. 17x9 = 153 ROACHs, 32x9 = 288 ADCs. 9x2 = 18 switches
153 x 5K x 1K +18x7.5K = 1188 K US (should plus computer, cooling, phase switching…)
* CASPER’s estimation
** Based on low quantity. 500US per each chip