Programmable amplifier with 1, 10, 100, and 1000 times magnification settings

Because the amplification factor of the bulb amplifier circuit is the reciprocal of the voltage division ratio of the feedback circuit
, and the voltage division ratio is determined from Δ2 to Δ5, the amplification factor can be selected by an external signal
. For example, if d=10 is required, in order to make the voltage division ratio 1/10,
a resistor voltage divider circuit of 90kQ:iokQ can be used. Calculate each amplification factor in this order
, and then the parameters in the circuit diagram can be obtained. Because
suitable voltage dividing resistors are selected in the resistor array , when the application requires high precision,     Crown- and D- at the input end of
the Fengcian port can be used . Dz is the input protection circuit. When using the technical circuit in the instrument It is also possible to use no crown, D, and Dz. In order to change the voltage dividing ratio of the feedback circuit to obtain variable gain, a front with a small input bias current should be selected. The FET input type OP requires an offset densification circuit in the variable gain DC amplifier, so choose the most suitable