LeCroy WAVERUNNER 6000 SERIES - Page 37

Buffer
Var gain
Full BW
200 MHzBuffer
Buffer 20 MHz
3
2
1
D
out
Overload
Differential
outputs
HF cal input
Input from 50 Ohm path
Input from 1MOhm path
Var Gain
Digital Interface
D
in
2
3
DC Loop In
DC Loop Out
Figure 4-10: HFE653 Block Diagram
4.6.3.5 Amplifier Signal Path – The following diagrams illustrate the signal
path taken during the various different scope input coupling and input
attenuation modes:
4.6.3.5.1 Power Off State –
+
-
HFE653
A
B
C
To trigg er
20 db
RL1
RL4
RL2
RL8
÷10
÷10
AC / DC
Isolation Relay
Used during Cal
HF Cal Signal
50
50
50 Ohm Offset
Var Gain
1 MOhm Offset
DAC
Relay
Control
1 MOhm Offset
50 Ohm Offset
Var Gain
6
Channel Input
Serial Bus
To ADC
To ADC
RL6
RL3
3 db
50 Ohm / Hi-Z
Thermal
Link
Thermal
Reference
Overload
- 5V
+ 5V
Hi-Z
buffer
buffer
RL1
÷10
boost
cap
U15
Q11
Q2 &
Q1
Figure 4-11 Front End Power Off State Block Diagram
Theory of Operation 4-15