The amplifier gain is 2, as the network impedance is 5 kΩ, and the amplifier
uses 10 kΩ in the feedback.
The linear transfer function of a 3-bit DAC is shown in Figure 5.8. In this case,
there are eight steps with the maximum voltage equal to seven-eighths of the reference
voltage [5].
An alternative method to resistor ladders used in integrated circuit DACs is a
current mirror technique to provide the transfer function. A 4-bit DAC using a current
mirror is shown in Figure 5.9. The ratios of the sizes of the P-MOS devices to
the reference P-MOS device are binary, to give binary current ratios when the
N-MOS devices in series with the P devices are turned On. Thus, the current
through R2 is proportional to the value of the binary input. Large ratios of device