ABSTRACT
High input impedance of the amplifier's have very common use, usually they are used to enlarge such as accelerometers, pickups and other crystal transducer output signal of such sensors. Internal impedance of these sensors is high, the output of the signal is weak. Sensor preamplifier should have high input impedance, to obtain the sensor output signal.
In the circuit design process, often use the bootstrap capacitor bootstrap circuit consisting of a number of performance indicators to improve the circuit, Such as increasing the circuit's input impedance, improve the circuit's gain and expand of the circuit's dynamic range, etc. Based on the amplifier's basic analysis , make comparison of all common high-current amplifier input impedance and working principle. And in accordance with task requirements, put forward and make use of ordinary quad op amp and build a bootstrap capacitor low-cost high input impedance circuit.
Keywords: High input impedance, Bootstrap circuit, Op amp