Rev 1.1 | SC5317A & SC5318A
Hardware Manual
SignalCore, Inc.
14
SC5317A & SC5318A Hardware Manual
have it remain powered on to maintain its temperature stability. Like the VCXO, it is also phase locked to
the external source.
LO Ports
There are 2 selectable LO ports, one located in the front of the device and the other on the opposite end
(rear). The port in the front is shared between the external LO and reference clock. A coupler exists
internally to direct the 10 MHz reference signal to the internal LO circuitry for phase locking. The
frequency range of the LO is between 6 GHz and 18 GHz and its signal can be doubled with the internal
doubler to 26.5 GHz. The input frequency range of the doubler is from 13.5 GHz to 27 GHz.
The Interface Module
The following figure shows the power and control interface block for the SC5318A. All supply rails are
produced on board; their voltages are regulated and actively filtered to keep noise to a minimum. Thus,
these downconverters are tolerant to “dirty” external power supplies.
Figure 6. Block diagram of the power and interface module
4
Hardware Registers
The set of hardware registers of the downconverter may be divided into a configuration set and a query
set; the configuration registers are write-only registers to set up the states of the device, while the query
registers request the device to prepare and send back data associated with them. The registers are
identical for all communication interfaces: USB, RS232, and SPI. Data communication to all interfaces are
sent in 1 byte wide, that is, data is transferred byte-by-byte. Register data lengths vary in size, and it is
important that the correct number of bytes are sent for the corresponding register. Failure to do so may
cause communication to lock-up and the device to become unresponsive.
Configuration Registers
These are write-only registers to configure the device. The registers vary in length to reduce redundant
data and improve the communication speed, especially for SPI and RS232 interfaces. Furthermore, it is
vitally important that the length of data written to a register is exact because failure to do so will cause
the interfaces to misinterpret the incoming data, leaving the device in a stalled state. The total number of
+18V, +10V, +5V, +3.3V,
-5V, -10V
To LO & SignalChain Module
MCU
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SC5317A
SC5318A