High-speed preamplifier for measurement that reduces noise with dual transistors

The difference between the Bong circuit and the ordinary differential amplifier circuit is that it has a
voltage-current conversion circuit composed of rPl, using R. and Rlo
divide the voltage enclosed by the OP amplifier, and then convert it into current for feedback. The voltage gain of this circuit can be calculated
    according to the type A! + VRi) × (1, - Rioj_R.)
    - - Rs .
If four'+v crown. It is about cricket oQ, according to ugly s=33<2～'§3kC!.
The magnification factor 4 can be in the range of l-l000.
    Because the base of the dual transistor Fr is connected to -, it is
trusted by the 3.9V Qi Na diode, so the common mode input voltage will be reduced, and
the characteristics of the OP amplifier cannot be used, so attention should be paid to it. VRs is connected in series with the collector resistors Ri and Rz of the differential amplification transistor to perform offset adjustment. If there is a zero-point drift
in the back end of the circuit , VRZo may not be used.     If the amplification factor is reduced in a multi-stage amplification circuit, oscillation will inevitably occur . terminal, so a phase compensation circuit (i,, and,.) needs to be added. The component parameters are determined by the minimum gain.