The Sr850 Functional Diagram - Stanford Research Systems SR850 User Manual

THE FUNCTIONAL SR850
The functional block diagram of the SR850 DSP
Lock-In Amplifier is shown below. The functions in
the gray area are handled by the digital signal pro-
cessor (DSP). We'll discuss the DSP aspects of
the SR850 as they come up in each functional
block description.
Low Noise
Differential
Amp
A
Voltage
B
Current
I
Reference In
Sine or TTL
Discriminator
SR850 FUNCTIONAL BLOCK DIAGRAM
50/60 Hz 100/120 Hz
Notch Notch
Filter Filter
Phase
PLL
Shifter
Phase Internal
Locked Oscillator
Loop
3-5
Gain
90°
Phase
Shift
Phase
Sensitive
Detector
Phase
Sensitive
Detector
SR850 Basics
DC Gain
Offset
Expand
Low
Pass
Filter
R and
Ø Calc
Low
Pass
Filter
DC Gain
Offset
Expand
Discriminator
Y Out
R
Ø
X Out
Sine Out
TTL Out