AD9995 Analog Devices, AD9995 Datasheet - Page 22

• Manufacturer Part Number: AD9995
• Description: 12-Bit CCD Signal Processor with Precision Timing Generator
• Manufacturer: Analog Devices

The example shown in Figure 22 illustrates this operation. The
first toggle position is 2, and the second toggle position is 9. In
non-Multiplier mode, this causes the V-sequence to toggle at
pixel 2 and then pixel 9 within a single HD line. However, toggle
positions are now multiplied by the VTPLEN = 4, so the first
toggle occurs at pixel count 8 and the second toggle occurs at
pixel count 36. Sweep mode has also been enabled to allow the
toggle positions to cross the HD line boundaries.
Vertical Sensor Gate (Shift Gate) Patterns
In an interline CCD, the vertical sensor gates (VSG) are used
to transfer the pixel charges from the light-sensitive image area
into light-shielded vertical registers. From the light-shield verti-
cal registers, the image is then read out line-by-line by using the
vertical transfer pulses V1–V6 in conjunction with the high speed
horizontal clocks.
Register
SGPOL
SGTOG1
SGTOG2
AD9995
VSG PATTERNS
VPATLEN
NUMBER
V1–V6
PIXEL
HD
VD
HD
MULTIPLIER MODE V-PATTERN GROUP PROPERTIES:
1. START POLARITY (ABOVE: STARTPOL = 0)
2. FIRST, SECOND, AND THIRD TOGGLE POSITIONS (ABOVE: VTOG1 = 2, VTOG2 = 9)
3. LENGTH OF VPAT COUNTER (ABOVE: VPATLEN = 4). THIS IS THE MINIMUM RESOLUTION FOR TOGGLE POSITION CHANGES.
4. TOGGLE POSITIONS OCCUR AT LOCATION EQUAL TO (VTOG  VPATLEN)
5. IF SWEEP REGION IS ENABLED, THE V-PULSES MAY ALSO CROSS THE HD BOUNDRIES, AS SHOWN ABOVE
1
PROGRAMMABLE SETTINGS FOR EACH PATTERN:
1. START POLARITY OF PULSE
2. FIRST TOGGLE POSITION
3. SECOND TOGGLE POSITION
4. ACTIVE LINE FOR VSG PULSES WITHIN THE FIELD (PROGRAMMABLE IN THE FIELD REGISTER, NOT FOR EACH PATTERN)
1
1
1
2
2
2
2
Length
1b
12b
12b
3
3
3
3
3
START POSITION OF VPAT GROUP IS STILL PROGRAMMED IN THE V-SEQUENCE REGISTERS
Figure 22. Example of Multiplier Region for Wide Vertical PulseTiming
4
4 1
4
4 5
Table IX. VSG Pattern Registers (also see Field Registers in Table VII)
1
5
6
6
2
2
3
3
7
7
8
8
4
4
4
Figure 23. Vertical Sensor Gate Pulse Placement
2
1
1
9 1
9 10 1
2
2
0 11 1
3
3
1 12 1
Range
High/Low
0–4095 Pixel Location
0–4095 Pixel Location
4
4
2 13 1
1
1
3 14 1
2
2
4 15 1
3
3
5 16 1
4
4
5
6 17 1
1
1
7 18 1
–22–
2
2
8 19 2
3
3
9 20 2
Table IX contains the summary of the VSG pattern registers. The
AD9995 has five VSG outputs, VSG1–VSG5. Each of the out-
puts can be assigned to one of four programmed patterns by using
the SGPATSEL registers. Each pattern is generated in a similar
manner as the V-pattern groups, with a programmable start polar-
ity (SGPOL), first toggle position (SGTOG1), and second toggle
position (SGTOG2). The active line where the VSG1–VSG5
pulses occur is programmable using the SGLINE1 and SGLINE2
registers. Additionally, any of the VSG1–VSG5 pulses may be
individually disabled by using the SGMASK register. The individ-
ual masking allows all of the SG patterns to be preprogrammed,
and the appropriate pulses for the different fields can be separately
enabled. For maximum flexibility, the SGPATSEL, SGMASK,
and SGLINE registers are separately programmable for each field.
More detail is given in the Complete Field section.
4
4
0 21 2
1
1
1 22 2
4
1
2
2
2 23 2
3
3
3 24 2
2
4
4
4 25 2
1
1
5 26 2
Description
Sensor Gate Starting Polarity for SG Pattern 0–3
First Toggle Position for SG Pattern 0–3
Second Toggle Position for SG Pattern 0–3
3
2
2
6 27 2
3
3
7 28 2
4
4 1
8 29 3
1
9 30 3
2
2
0 31 3
3
3
1 32 3
4
4 1
5
2 33 3
1
3 34 3
2
2
4 35 3
3
3
5 36 3
4 1
4 1
6 3
6 3
6 3
6 37 3
2
4
7 38 3
2
2
8 39 4
3
3
9 40
4
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