Difference between revisions of "SiPM Amplifier Components"

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== Bypass Circuits ==
 
== Bypass Circuits ==
  
The passive components used to bypass high frequency noise to clean up DC levels were picked as follows. The 10 nF capacitor frequently used in the circuit was deemed a good choice - high enough without raising concerns of introducing much inductance. This was also Photonique's choice for bypass capacitors in their prototype amplifier. The resistance on the bases of relevant transistors should be same or lower than that of the bench prototype (200 &omega). 154 Ω is sufficient, leading to a low pass filter with 3 dB point of 100 kHz. Frequencies below this point are well out of the amplifier's band (see [[SiPM Amplifier Signal Analysis]].
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The passive components used to bypass high frequency noise to clean up DC levels were picked as follows. The 10 nF capacitor frequently used in the circuit was deemed a good choice - high enough without raising concerns of introducing much inductance. This was also Photonique's choice for bypass capacitors in their prototype amplifier. The resistance on the bases of relevant transistors should be same or lower than that of the bench prototype (200 Ω). 154 Ω is sufficient, leading to a low pass filter with 3 dB point of 100 kHz. Frequencies below this point are well out of the amplifier's band (see [[SiPM Amplifier Signal Analysis]].
  
 
The bypass circuit for the gate of the MOSFET switch takes more care. Gate resistance forms a voltage divider with resistance on the Source leg. Given the low value of R<sub>d</sub>: 82&nbsp;&Omega;, and the MOSFET specification of V<sub>GS</sub>&nbsp;=&nbsp;-4 as the maximum pinch-off value, R<sub>G</sub> of 18&nbsp;&Omega; is a good choice. The resulting V<sub>GS</sub> when the controlling voltage is pulled down ground is -4.1&nbsp;V.
 
The bypass circuit for the gate of the MOSFET switch takes more care. Gate resistance forms a voltage divider with resistance on the Source leg. Given the low value of R<sub>d</sub>: 82&nbsp;&Omega;, and the MOSFET specification of V<sub>GS</sub>&nbsp;=&nbsp;-4 as the maximum pinch-off value, R<sub>G</sub> of 18&nbsp;&Omega; is a good choice. The resulting V<sub>GS</sub> when the controlling voltage is pulled down ground is -4.1&nbsp;V.

Revision as of 06:09, 17 March 2009

The following presents a more concrete description of components necessary to implement the amplifier design discussed in the SiPM Amplifier Optimization section.


Amplifier and summing circuit component designations.


Resistors (amp)
R1 100
R2 10
R0 560 Ω
R3 1000 Ω
R4 330 Ω
R5 470 Ω
R6 50 Ω
R7 1360 Ω
R9 1000 Ω
Resistors (sum)
Ra 120 Ω
Rb 1220 Ω
Rc 100 Ω
Rd 82 Ω
Re 3300 Ω
Rf 680 Ω
Rg 560 Ω
Rh 180 Ω
Ri 2000 Ω
Rj 392 Ω
RE 700 Ω
Capacitors
C1 10 nF
C2 10 nF
C3 10 nF
C4 1 nF
C5 10 nF
Ca 1 nF
Cc 10 nF
Cd 1 nF
Ch 10 nF
CC 1 nF
Transistors
Num. Label Polarity
1 j NPN
2 k PNP
3 l PNP
4 m NPN
5 n NPN
6 o PNP
7 p PNP
8 q NPN
Transistor Parts
Type Component
BJT NPN Infineon BFR92P
BJT PNP NXP (Philips) BFT92W
MOSFET NXP (Philips) BF1108(R)
Bypass Components
Name Value
CBi 10 nF
RBi 154 Ω
RG 18 Ω

Bypass Circuits

The passive components used to bypass high frequency noise to clean up DC levels were picked as follows. The 10 nF capacitor frequently used in the circuit was deemed a good choice - high enough without raising concerns of introducing much inductance. This was also Photonique's choice for bypass capacitors in their prototype amplifier. The resistance on the bases of relevant transistors should be same or lower than that of the bench prototype (200 Ω). 154 Ω is sufficient, leading to a low pass filter with 3 dB point of 100 kHz. Frequencies below this point are well out of the amplifier's band (see SiPM Amplifier Signal Analysis.

The bypass circuit for the gate of the MOSFET switch takes more care. Gate resistance forms a voltage divider with resistance on the Source leg. Given the low value of Rd: 82 Ω, and the MOSFET specification of VGS = -4 as the maximum pinch-off value, RG of 18 Ω is a good choice. The resulting VGS when the controlling voltage is pulled down ground is -4.1 V.