22Mhz sample and hold circuit

[Roff]

OK, here's the circuit I came up with. You might need to change some values. For low offset voltage, the diodes in the bridge need to be matched. You can probably find a better op amp. It just needs to have low input bias current, high bandwidth, and high slew rate. I picked this one because it was in my library.
I'm including the .ASC file in case anyone wants to simulate it in LTspice.

Here are the models for the diodes and the transistors.

*
.SUBCKT 1ps70sb10 1 3 
* The Resistor R1 does not reflect 
* a physical device.  Instead it
* improves modeling in the reverse 
* mode of operation.
*
R1 1 3 3.6E+07 
D1 1 3 1ps70sb10  
*
.MODEL 1ps70sb10 D( 
+    IS = 2.117E-07 
+    N = 1.016 
+    BV = 36 
+    IBV = 1.196E-06 
+    RS = 2.637 
+    CJO = 1.114E-11 
+    VJ = 0.2013 
+    M = 0.3868 
+    FC = 0 
+    TT = 0 
+    EG = 0.69 
+    XTI = 2)

.MODEL MPSH10 NPN (Is=69.28E-18 Xti=3 Eg=1.11 Vaf=100 Bf=308.6 Ne=1.197 Ise=69.28E-18 Ikf=22.83m Xtb=1.5 Br=1.11 Nc=2 Isc=0 Ikr=0 Rc=4 Cjc=1.042p Mjc=.2468 Vjc=.75 Fc=.5 Cje=1.52p Mje=.3223 Vje=.75 Tr=1.558n Tf=135.8p Itf=.27 Vtf=10 Xtf=30 Rb=10)

.MODEL MPSH81 PNP(Is=10f Xti=3 Eg=1.11 Vaf=100 Bf=133.8 Ise=1.678p Ne=2.159 Ikf=.1658 Nk=.901 Xtb=1.5 Var=100 Br=1 Isc=9.519n Nc=3.88 Ikr=5.813 Rc=7.838 Cjc=2.81p Mjc=.1615 Vjc=.8282 Fc=.5 Cje=2.695p Mje=.3214 Vje=.7026 Tr=11.32n Tf=97.83p Itf=69.29 Xtf=599u Vtf=10)

 

[wyiancwc88]

thanks a lot Roff. Thanks, u really helped me a lot. I'll try to simulate the circuit now, thanks again.