Multiplexing instrumentation preamplifier

摘要

An oscilloscope preamplifier includes N inputs and Z outputs. A programmable cross-point multiplexer provides a first operating mode in which each of N inputs is connected to a different output thereby providing a preamplifier with Z channels, a second operating mode in which one input is multiplexed to all the outputs which are interleaved to maximize the sampling rate, and a range of operating modes in between. The programmable multiplexer includes a switching amplifier connected between each input and each output. Dials on the preamp select the mode by causing a microprocessor to program latches which activate or deactivate the switching amplifiers. A voltage divider is connected across inputs of the multiplexer to provide a programmable attenuator with selectable attenuation levels.