AD8368

Rev. A | Page 13 of 20

GAIN CONTROL INTERFACE

The AD8368 has a linear-in-dB gain control interface that can

be operated in either a gain-up mode or gain-down mode. In

the gain-up mode with the MODE pin pulled high, the gain

increases with increasing gain voltages. In the gain-down mode,

with the MODE pin pulled low, the gain decreases with increasing

gain voltages. In both modes of operation, the gain control

slope is maintained at +37.5 dB/V or −38 dB/V (depending

on mode selection) over temperature, supply, and process as

with the on-board detector around the VGA, the MODE pin

has to be pulled low.

The gain functions for MODE pulled high and low are given

respectively by:

25

–15

–10

–5

0

5

10

15

20

4

–4

–3

–2

–1

0

1

2

3

01

0.8

0.6

0.4

0.2

.0

GAIN_H

GAIN_L

ERROR_H

ERROR_L

As shown in Figure 32, the gain function can be either an

MODE pin.