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The magnitude of the differential VCA input signal (from the LNP or an external source) is reduced by a programmable attenuation factor, set by the analog VCA Control Voltage (VCACNTL) at pin 43. The maximum attenuation factor is further programmable by using the three MGS bits (pins 40-42). Figure 3 illustrates this dual-adjustable charac- teristic. Internally, the signal is attenuated by having the analog VCACNTL vary the channel resistance of a set of shunt-connected FET transistors. The MGS bits effectively adjust the overall size of the shunt FET by switching parallel components in or out under logic control. At any given maximum gain setting, the analog variable gain characteris- tic is linear in dB as a function of the control voltage, and is created as a piecewise approximation of an ideal dB-linear transfer function. The VCA gain control circuitry is common to both channels of the VCA2616 and VCA2611.