Tektronix DG2030 User Manual page 44

Operating Basics
CPU Unit
The CPU unit controls the instrument. The CPU unit includes ROM, RAM, and
an I/O interface.
The ROM memory holds the program code that implements all the supported
functions. The ROM contents are loaded at the factory.
The RAM memory holds a variety of information required by the CPU. The
contents of RAM change according to the instrument's operating state. Since the
contents of RAM are retained by a built-in battery even when the instrument is
turned off, the main instrument settings will still be in effect the next time the
instrument is turned on. The pattern data memory and the sequence data
memory, which are described later as a conceptual data model, are actually stored
in one section of this RAM.
External interfaces include GPIB and RS-232 interfaces for remote control, a
floppy disk drive controller, and a user interface consisting of the display and the
front panel.
Pattern Generation Unit
The pattern generation unit generates digital pattern signals based on the pattern
data and sequence data specified by the user. This unit includes a pattern control
circuit, pattern memory, and sequence memory.
Pattern memory and sequence memory are high-speed memories that hold the
pattern data and sequence data, which are described later in this section. These
memories supply pattern data to the pattern control circuit.
Clock Unit
The clock unit generates the clock signals that generate the data patterns. It also
detects and synchronizes external trigger signals.
You can select whether the phase-lock-loop (PLL) circuit is used in clock signal
generation or not. When the PLL circuit is used (PLL on), the clock unit
generates a clock signal synchronized to an internal crystal oscillator. This
provides an output with excellent frequency precision. When the PLL circuit is
not used (PLL off), the clock unit can generate a clock output synchronized with
an external trigger signal, although the frequency precision is lower. The PLL
circuit can be turned on or off depending on the application.
Output Channels
The output channels provide variable output levels and digital signals to the
device under test.
The output channels level-convert the pattern signals from the pattern generation
unit to output signals appropriate for the device under test. They also handle fine
adjustment of specific bit timing.
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DG2030 User Manual
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