j1PCI663 shame dynamic is input, differential output type of IC, but this circuit has a single-ended output, input
terminal resistance chu l (50Q), comb straight coupling. Because the output voltage is approximately the same phase 3V, it is necessary to use a capacitor c: aiE line AC coupling. When using single-ended output differential output terminals If not using open-circuit, the characteristics will change, so this circuit is connected to the resistance fart 'ugly chu, in order to achieve balance. Magnification is connected by a differential input differential transistor emitter resistor Rs. OK, short circuit, which is about 300 times when looQ}} 1.2kQ 100 times when 20 times. If lkQ variable resistor, you can arbitrarily change the magnification. That is the change to the closed-loop magnification, it will not change the frequency characteristics of the circuit which is superior to ordinary OP amplifier place.