Single-Ended Input to Differential Output Circuit Using a Fully-Differential Amplifier

Design Goals

Input	Output	Supply
Single-Ended	Differential	V_cc	V_ee
0V to 1V	16Vpp	10V	0V

Output Common-Mode	3 dB Bandwidth	AC Gain (Gac)
5V	3MHz	16V/V

This design uses a fully-differential amplifier (FDA) as a single-ended input to differential output amplifier.

The ratio R₄/R₃, equal to R₂/(R₅||R₆), sets the gain of the amplifier.
The main difference between a single-ended input and a differential input is that the available input swing is only half. This is because one of the input voltages is fixed at a reference.
It is recommended to set this reference to mid-input signal range, rather than the min-input, to induce polarity reversal in the measured differential input. This preserves the ability of the outputs to crossover, which provides the doubling of output swing possible with an FDA.
The impedance of the reference voltage must be equal to the signal input resistor. This can be done by creating a resistor divider with a Thevnin equivalent of the correct reference voltage and impedance.

Find the resistor divider with that produces a 0.5V, 1-kΩ reference from Vs = 10V.
Verify that the minimum input of 0V and the maximum input of 1V result in an output within the 9.4V range available for V_ocm = 5V.
Since the resistor divider acts like a 0.5V reference, the measured differential input for a 0V V_IN is:
The output is:
Likewise, for a 1 V input:

Note:

With a reference voltage of 0V, a 1V input results in an output voltage greater than the maximum output range of the amplifier.

AC Simulation Results

Transient Simulation Results