The input divider, R1 and the sum of R2 and R3, sets the overall transfer function of the circuit. To increase the transfer function, decrease the Control Voltage and the value of R1. Varying the value of R4 will optimize the linearity of the circuit. One can achieve a very linear transfer function (< 1 dB/V) by driving the attenuator over a smaller portion of its dynamic range. In the case of the AT10-0009 and AT10-0017 attenuators, this would be limited to a dynamic range of 28 and 25 dB, respectively. Temperature compensation is a function temperature coefficient of the thermistor, R3, and the ratio of R2 to R3, and can only be optimized once the transfer function and linearity component values have been established. |