VXI Technology, Inc.

SIGNAL COMPARISON

Signal comparison between the input signal and a user-defined reference voltage is accomplished by a differential amplifier, an 8-bit Digital to Analog Converter or DAC and a voltage comparator (see Figure 5-2). The DAC, U8, is loaded by the control FPGA, U3, and provides the reference voltage TRIGLEV1.

 

 

 

 

100K

 

 

 

 

 

 

 

 

 

10K

K9

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

10pf

 

 

 

 

 

(FROM FRONT

-CH1

100K

 

-

 

 

 

 

 

 

 

6K

 

 

 

 

 

 

U17A

 

 

 

 

 

 

 

 

 

 

 

 

PANEL CONNECTOR)

100K

 

 

 

 

 

 

 

 

 

2K

 

 

 

 

+CH1

 

 

+

 

 

 

 

 

 

 

 

 

 

 

 

 

VMIP BUS

 

 

 

100K

 

 

 

 

 

 

 

 

 

10K

K9

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VCC

 

 

 

 

 

 

 

BUFCH1

-

4.7K

 

 

 

 

 

 

 

4.7K

 

CONTROL

 

 

 

 

 

 

DACDATA

D A C

TRIGLEV1

1K

 

U13A

 

FPGA

 

 

 

 

 

DACLOAD#

+

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

DACCLK

 

 

 

 

 

 

 

 

 

 

U8

 

 

 

470K

 

 

 

 

 

 

 

 

 

 

U3

 

 

 

 

 

 

 

COMPCH1

 

 

 

 

 

 

 

 

 

 

CONTROL

 

 

 

 

 

 

Address

 

 

 

 

 

 

 

 

 

0-5, 29

CONTROL

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BUFFER

 

 

 

 

 

 

 

 

U1

 

 

 

 

 

 

 

 

Data 0-15

DATA

 

Data

 

 

 

 

 

 

 

BUFFER

 

 

 

 

 

 

 

DOE*

 

 

 

 

 

 

 

 

 

 

U4

 

 

 

 

 

 

 

 

 

 

 

 

FIGURE 5-2: SIGNAL COMPARISON

 

 

The command to specify the reference voltage is received in the data and command buffers and subsequently transferred to the control FPGA at U3. U3 then converts the parallel data to an 8-bit serial data word DACDATA and synchs the output of this word to the 10 MHz gated clock DACCLK. Signal DACLOAD1, for Channel 1, goes high providing the control necessary to shift the serial data into DAC 1. The output TRIGLEV1 of the U8, is used by the comparator U13A as the reference.

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VM4016 Theory of Operation

Page 90
Image 90
VXI VM4016 user manual Signal Comparison