DSO150- Input gain

The DSO 150  input gain  is a 4 stages  circuit :



  • G1 is driven by SENSEL3 (aka PA14) and enables switching between a gain of 10/11 (SENSEL3=1) and 10/1100 (SENSEL3=0)
  • G2 gain is 2
  • G3 gain is driven by SENSEL0/1/2 (PA11/12/13) and can go from /1 to /40, more on that later
  • G4 gain is (1+1000/150)=~ 7.7, additionally the signal is shifted by 1000/680 volt = 1.47 v

The overall gain can vary from 10/11*2*1*7.7 => ~ x14 to 10/1100*2/40*7.7 => ~ /285 

The SENSEL0..2 order is a bit weird :

Gain       SENSEL0..2
GND           1
/1                4
/2                6
/4                7
/10              0
/20              5
/40              3

Ultimately the gain follows this table :

SENSEL0..3                Gain
0                                    /71
1                                    GND
2                                    NC
3                                    /286
4                                    /7
5                                    /143
6                                    /14
7                                    /29


8                                    x1.4
9                                    GND
10                                  NC
11                                  x0.35
12                                  x14
13                                  x0.7
14                                  x7
15                                  x3.5






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