The MPA4609 is one of the lowest noise, fixed gain, 5V single-supply, differential amplifiers available for amplification of low-level signals in a variety of system applications. The chip has two sets of four differential input, low-noise amplifiers that are routed to four output stages. Two standard logic input select lines control which set of four input preamps are active. For applications such as tape recorders, four heads in forward and four heads in reverse can be selected at one time.
The quad consists of eight differential low noise (0.65nV/√Hz )
voltage preamps. Two select lines control two pairs of inputs.
Each of the output stages provides a nominal 470Ω-output
impedance on each half of the differential output stages. The
overall gain of 190V/V may be attenuated by adding an
external load resistor between each set of differential outputs.
For example, adding an external 940Ω resistor across
the output pins will reduce the nominal differential gain by
half to 95V/V.
Internal biasing controls the differential inputs to 2.0V and outputs to a 2.1V common-mode operating level. The maximum no-load differential output swing is 3.5VPP centered on the 2.1V bias level. A low input offset voltage and bias current offset holds the maximum output differential offset to < ±350mV for no-load conditions.
The low (3.5pF) input capacitance makes this part useable for applications requiring wide bandwidth and multiple pickups often seen in testers, medical equipment, twisted pair receivers, and optical systems. The single +5V supply and its low quiescent current of 50mA make it exceptionally attractive in multi-channel, low power, high bandwidth designs.