These specifications are intended to serve as a broad guide, with variable gain and attenuation stages set at midpoints. As variable stages are adjusted, performance generally improves.
Table 1: Input Parameters for Analysis
Table 2: Rx and Tx Specifications
|Value (lna pa)
|Rx Chain Analysis
|Tx Chain Analysis
|-20 - 5
|40 - 70
Cyan benefits from a highly modular design consisting of several boards. Each board is connected across a rugged backplane to support its operation (Figure 1). The power board provides power to the various other boards. The digital board provides an interface to control, configure, and send/receive data to/from the receive (Rx), transmit (Tx) radio boards, and configures the time board. Clock distribution extends from the Time board, which provides a very clean and stable clock distribution network. The default product supports 8 fully independent transmit and receive chains, though this may be customized to support up to 16 transmit boards or 16 receive boards for receive or transmit only capabilities.
Figure 1: Overall system block diagram.
Cyan uses an 12V, 1000W, over current protected, DC power supply and accepts a standard IEC320 C13 120-240VAC computer power cable at the rear of the unit. The power board distributes power to the backplane as shown in Figure 2.
Figure 2: Power board system block diagram
The Cyan digital board provides the digital processing that configures the Cyan radio resources. It consists of an Intel Stratix 10 SOC FPGA, which includes an ARM Cortex-A53 quad-core processor on the FPGA (Figure 3). The ARM (HPS) portion of the board hosts various applications through which Cyan can be configured, along with the UART serial ports, which may be used to communicate with the various modules. A separate high speed link allows serial data to be shared directly between the Rx and Tx boards and the FPGA fabric. This link also allows the data to be shared between the FPGA fabric and the 40Gbps interface (accessed using the qSFP| ports on the front of the device). Other peripherals, including USB devices, are accessed through the HPS portion of the FPGA.
The Cyan HPS is connected to a 2GB DDR4 interface that supporting ECC. The FPGA fabric is connected to two 4GB DDR4 RAM banks.
Figure 3: Digital board system block diagram.
Cyan time distribution is fairly robust. The internal reference source is an oven-controlled crystal oscillator (OCXO) that provides a very stable (5ppb) and accurate 10MHz signal that supports tuning using the AD5624R nanoDAC. A single ended external reference clock may also be used, provided it meets the input swing requirements listed on the specifications page
The default external reference frequency should be 10 MHz, but it is possible to use an unless using custom dividers/logic (the hardware supports various external reference frequencies, but this is not exposed to the user).
The default configuration has been factory calibrated to provide a known (in-phase), deterministic relationship for all LMK04828 outputs. The Leading edge of all outputs and internal VCOs have been synchronized at the reference inputs of all frequency synthesizers, converters, and transceivers.
Figure 4: Time Board Architecture.
Receive Board Radio Chain
The Cyan receive board consists of a radio front end terminating with the dual channel, 16bit, ADS54J60 1GSPS ADC at 1GSPS. It may also be used with the ADC32RF45, a dual channel, 12-bit, 3GSPS ADC. Each Rx radio board uses same architecture for each channel.
Figure 5: Rx Board RF Channel
Transmit Board Radio Chain
The Cyan transmit board consists of a radio front end originating with the AD9163 dual channel, 16bit, 1GSPS DAC. It is also possible to use the AD9162 DAC, which provides up to 2GHz of instantaneous bandwidth. This architecture is repeated for each transmit channel, as shown in Figure 6.
Figure 6: Tx Board RF Channel
FPGA DSP Chains
A simplified illustration of the DSP chains for transmit (Figure 7 ) and receive (Figure 8) provides a broad outline of the FPGA processing from the qSFP ports to the converters. The current architecture supports 40GBASE-R, but is upgradable to 100GBASE-R.
Figure 7: Simplified Tx DSP Chain.
Figure 8: Simplified Rx DSP Chain.