Redesigning SSM2018T VCA for Single +Vcc Supply Operation Instead of Dual Supply

Not sure which section this belongs. A VCA requires a +/- Vcc as its limits and it uses the ground as the baseline. How can the VCA (i.e. SSM2018T) be redesigned to only have a single source of +Vcc and ground?

I believe the way to use the SSM2018T with a single supply is to provide bias the GND pin at midway between V+ and V-. The Op Amp inputs should be kept more than 2 volts from V+ and GND.

The circuit shown here can provide the one-half V+.

This circuit provides the virtual GND at V+/2 and it translates the voltage control from GND referenced to V+/2 referenced.

What if I have this circuit below and I want to do away the V-? I want it t be just V+ and GND with no additional op amps.

http://www.analog.com/static/imported-files/data_sheets_obsolete/SSM2018T_2118T.pdf

Figure 45 shows how to operate the device from a single power supply. They recommend driving the GND pin 13 from a "very low impedance." Vcontrol is now referenced to GND and with the circuit shown in Figure 45 its gain will be altered. The circuit I provided does not change the Vcontrol gain.

If you need to avoid adding an op amp the GND pin can be biased with a very stiff voltage divider (how stiff?) or a zener and resistor. The zener current needs to be more than the maximum current the GND pin would ever draw plus enough to operate the zener in its low dynamic resistance region. Another way to go is with an emitter follower (one transistor) buffering a voltage divider. The GND voltage will experience the emitter-base voltage tempco of the transistor - about -2 mV/deg C. A buffer can be constructed using two transistors (NPN and PNP) with the emitter-base voltages offsetting each other. This will result in a lower tempco.

All of this is a tradeoff: For maximum performance the Op Amp derived GND should be used and if performance can be given up, one of the other GND referencing methods can be used.