The analog front end of oscilloscope is the key to determine the bandwidth
The key to determine the bandwidth is the analog front end of the oscilloscope, including attenuator, amplifier and related circuits. It is the gate through which the measured signal enters the oscilloscope. The bandwidth of the test signal of the oscilloscope is determined by the bandwidth of the analog front end in many cases, which directly affects the background noise and range of the oscilloscope. The design of analog front end takes up more than half of the work in the hardware design of oscilloscope, and determines the hardware performance of oscilloscope to a large extent. For the analog front end, the main performance indexes affecting the oscilloscope include:
● analog bandwidth, including the amplitude-frequency response characteristics of the measured signal, in the time domain as rise time index and overshoot performance index;
● dynamic range of input signal amplitude (range from minimum vertical sensitivity to maximum vertical sensitivity for non-digital processing);
● initial error characteristics and temperature drift characteristics of dc gain accuracy and offset accuracy;
● input impedance characteristics (parasitic capacitance of resistance in parallel) influence on the circuit under test with or without a probe.