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AD8352 SPICE Model and Input Voltage Range

Hello,

I'm planning a DC coupled front-end for the AD9434 12-Bit ADC using the AD8352 Fully Differential Driver, as recommended in the datasheet and indicated in Fig. 43 in the AD9434 datasheet.

Since I will use the AD8352 in a single-ended to differential configuration with an input signal symmetric around GND, I am interested about the input voltage range when using

a) symmetric +-2.5V supplies

b) asymmetric +3V, -2V supplies

c) +5V, 0V supply

which I could not find in the corresponding datasheet

Is there a SPICE model available?

Thanks and regards

typo
[edited by: eti_ch at 5:35 PM (GMT 0) on 23 Dec 2018]
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• Hi,

The nominal input common-mode voltage needs to be 1.9 V with respect to the negative supply, so for the three cases in the question, it needs to be at:

a)  1.9 - 2.5 = -0.6 V

b)  1.9 - 2 = -0.1 V

c)  1.9 - 0 = 1.9 V

The maximum input swing will be maximized with the common-mode set appropriately (1.9 V ideally, but at least within the 1.2 to 3.8 V range with respect to the negative supply), and it will mainly be limited by output compression, so it will depend on the gain setting:

Maximum input swing = (output swing at compression) / (voltage gain)

For example, for a gain setting of 12 dB (which is a voltage gain Av = 4):

Maximum input swing = 6 Vpp / 4 =1.5 Vpp differential

If a lower gain setting is used, there will be additional limitation due to the input stage. Please note that the ENB threshold is also with respect to the negative supply, and must be set appropriately.

Unfortunately, there is no official SPICE model available.

• Hi,

The nominal input common-mode voltage needs to be 1.9 V with respect to the negative supply, so for the three cases in the question, it needs to be at:

a)  1.9 - 2.5 = -0.6 V

b)  1.9 - 2 = -0.1 V

c)  1.9 - 0 = 1.9 V

The maximum input swing will be maximized with the common-mode set appropriately (1.9 V ideally, but at least within the 1.2 to 3.8 V range with respect to the negative supply), and it will mainly be limited by output compression, so it will depend on the gain setting:

Maximum input swing = (output swing at compression) / (voltage gain)

For example, for a gain setting of 12 dB (which is a voltage gain Av = 4):

Maximum input swing = 6 Vpp / 4 =1.5 Vpp differential

If a lower gain setting is used, there will be additional limitation due to the input stage. Please note that the ENB threshold is also with respect to the negative supply, and must be set appropriately.

Unfortunately, there is no official SPICE model available.

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