ADMV8502ACCZ-R7 datasheet(12/32 Pages) AD

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Data Sheet

ADMV8502

THEORY OF OPERATION

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Rev. 0 | 12 of 32

INTERPOLATION FUNCTIONS

The ADMV8502 has three interpolation functions that allow the

user to specify the fCENTER of the filter only using the fCENTER load

value, and then the appropriate capacitor codes are determined

automatically. To enable these functions, set the INTERPOLATE bit

(Register 0x050) high.Figure 22 shows a simplified diagram of the

interpolation functions.

When the interpolation functions are enabled, the fCENTER load

range is 0 to 255, where 0 corresponds to the lowest frequency and

255 corresponds to the highest frequency. For example, a value

of 0 corresponds to approximately 90 MHz and 255 corresponds

to approximately 225 MHz. The fCENTER load value is used to

determine the appropriate capacitor codes based on the on-chip

interpolation coefficients.

By default, the recommended interpolation coefficients are set for

nominal 9% bandwidth. The interpolation coefficients can be adjust-

ed between ± 2% of nominal bandwidth with reasonable insertion

loss. Narrower bandwidth down to approximately 5% can also be

achieved at the expense of insertion loss.

Figure 22. Interpolation Diagram

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