AD602 datasheet(13/33 Pages) AD

13 / 33 page

AD600/AD602

There are several options in connecting the gain-control inputs.

The choice depends on the desired SNR and gain error (output

ripple). The following examples feature the AD600; the

arguments generally apply to the AD602, with appropriate

changes to the gain values.

3.0

–0.5

2.5

2.0

1.5

1.0

0.5

SEQUENTIAL MODE (MAXIMUM SNR)

In the sequential mode of operation, the SNR is maintained at

its highest level for as much of the gain control range as

possible, as shown in Figure 22. Note here that the gain range is

0 dB to 80 dB. Figure 23, Figure 24, and Figure 25 show the

general connections to accomplish this. Both gain-control

inputs, C1HI and C2HI, are driven in parallel by a positive-only,

ground-referenced source with a range of 0 V to 2.5 V.

VO2 = 1.908V

Figure 22. SNR vs. Control Voltage Sequential Control (1 MHz Bandwidth)

An auxiliary amplifier that senses the voltage difference

between input and output commons is provided to reject this

common voltage.

Rev. F | Page 12 of 32

41.07dB

INPUT

0dB

–40.00dB

C1HI

C1LO

1.07dB

VG2

OUTPUT

0dB

–41.07dB

–42.14dB

C2HI

C2LO

41.07dB

VO1 = 0.592V

VG1

VC = 0V

–0.51dB

OUTPUT

Figure 23. AD600 Gain Control Input Calculations for Sequential Control Operation (A)

40dB

41.07dB

–0.51dB

C1HI

C1LO

–1.07dB

–41.63dB

40.56dB

41.07dB

C2HI

C2LO

INPUT

38.93dB

VO2 = 1.908V

VG2

VO1 = 0.592V

VG1

0dB

VC = 1.25V

Figure 24. AD600 Gain Control Input Calculations for Sequential Control Operation (B)

0dB

41.07dB

C1HI

C1LO

–2.14dB

41.07dB

C2HI

C2LO

INPUT

OUTPUT

80dB

0dB

VC = 2.5V

VO1 = 0.592V

VG1

VO2 = 1.908V

VG2

Figure 25. AD600 Gain Control Input Calculations for Sequential Control Operation (C)

AD602 Datasheet(PDF) 13 Page - Analog Devices

AD602 Datasheet(HTML) 13 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33

Datasheet Download

Link URL