Reset Button (Pin Hole); Functional Description; Overview; The Rf Input - SIGNALCORE SC5312A User Manual

PIN #
1
2
3
4
5

Reset Button (Pin Hole)

Behind this pin hole is the reset button, which is only available on the SC5308A. Using a pin to lightly
depress this momentary-action push button switch will cause a hard reset to the device, putting it back to
its default settings. All user settings will be lost. System reset capability can also be accessed through the
communication header connector.

3 Functional Description

Overview

The SC5312A uses USB as its primary interface with an optional SPI or RS232 interface. The SC5313A is a
PXIe version of the product. They are single-stage, direct conversion Inphase-Quadrature (IQ)
demodulating mixers. They can operate as a single-stage downconverter or as an IQ demodulator. These
modules operate in the 400 MHz to 6 GHz RF range with a typical 3 dB IF bandwidth of 160 MHz in single-
stage converter mode and 320 MHz in IQ mode. The RF input stage has adjustable gain to allow
adjustment of the incoming RF signal prior to the demodulation process for the purpose of optimizing RF
dynamic range. The IF stage has adjustable gain to ensure that linearity and noise of the IF output are
optimized. The modules have the necessary RF amplifiers, attenuators, IF amplifiers, and IF control via
DACs to allow the user to optimally operate the device over the entire frequency range as well as for both
small and large RF input levels. The following sections provide in depth information on how to optimize
the modules for linearity and signal-to-noise dynamic range.

The RF Input

In the design of the RF input section, care was taken to ensure that the dynamic range of the IQ
demodulator is preserved as seen at the input port of the device. This requires that the demodulator is not
driven too hard (high signal amplitude) or too soft (low signal amplitude). When the device is driven hard,
nonlinear effects dominate the system. When driven too softly, signal-to-noise dynamic range suffers. A
general rule is to apply more attenuation earlier in the RF signal path to improve linearity, and more gain
to improve signal-to-noise performance. As an example, for a given input signal level and while maintaining
a relatively constant output IF level, the user would switch in RF AMP#1 and apply attenuation on ATTEN#3
to improve signal-to-noise dynamic range. The factory default state sets all the RF amplifiers off, all
attenuators set to 0 dB attenuation, and the IF gain set to 8 dB (DAC code of 32). In this default state, the
device is optimized for a -10 dBm RF signal in the 1.0 GHz to 2.4 GHz range. The IF output is typically 0.5 V
- 1.0 V peak-to-peak differential at these settings.
©2013
USB Function Description
VBUS Vcc (+5 Volts)
D- Serial Data (neg)
D+ Serial Data (pos)
ID Not Used
GND Device Ground (also tied to connector shell)
Functional Description 11
Rev 2.1