
AD539
Rev. B | Page 16 of 20
BASIC DIVIDER CONNECTIONS
Standard Scaling
The AD539 provides excellent operation as a two-quadrant
analog divider in wideband, wide gain-range applications, with
the advantage of dual-channel operation.
Figure 25 shows the
simplest connections for division with a transfer function of
VY = VUVW/VX
Recalling that the nominal value of VU is 1 V, this can be
simplified to
VY = VW/VX
where all signals are expressed in volts. The circuit thus exhibits
unity gain for VX = 1 V and a gain of 40 dB when VX = 0.01 V.
The output swing is limited to ±2 V nominal full scale and ±4.2 V
peak (using a VS supply of at least 7.5 V for the AD539).
Because the maximum loss is 10 dB (at VX = 3.162 V), it follows
that the maximum input to VW should be ±6.3 V (4.4 V rms) for
low distortion applications and no more than ±13.4 V (9.5 V
rms) to avoid clipping. Note that offset adjustment is needed for
the op amps to maintain accurate dc levels at the output in high
gain applications: the noise gain is 6 V/VX, or 600 at VX = 0.01 V.
The gain magnitude response for this configuration using the
LH0032 op amps with nominally 12 pF compensation (HF
COMP, Pin 2, to VY1, Pin 3) and CF = 7 pF is shown in Figure 17; however, other amplifiers can also be used. Because there is some
manufacturing variation in the HF response of the op amps and
load conditions also affect the response, these capacitors should
be adjustable: 5 pF to 15 pF is recommended for both positions.
The bandwidth in this configuration is nominally 17 MHz at
VX = 3.162 V, 4.5 MHz at VX = 1 V, 350 kHz at VX = 0.1 V, and
35 kHz at VX = 0.01 V. The general recommendations regarding
the use of a good ground plane and power supply decoupling
should be carefully observed. Other suitable high speed op amps
for suitable applications circuits.
096
79-
025
1
2
3
4
16
15
14
13
5
12
6
11
7
10
8
9
AD539
VX
NUMERATOR 1
VW1
NUMERATOR 2
VW2
HF COMP
VY1
+VS
–VS
VY2
INPUT
COMMON
OUTPUT
COMMON
BASE
COMMON
W1
Z1
NC
3
2
2pF TO 15pF
LH0032
2pF TO
15pF
2pF TO
15pF
NOTES
1. DECOUPLE OP AMP SUPPLIES.
2pF TO 15pF
2
NC
CHAN1
OUTPUT
CHAN2
OUTPUT
Z2
W2
CC = 3nF
DENOMINATOR
INPUT, VX
VY1 = –
VW1
VX
VY2 = –
VW2
VX
0.47F
+5V
–7.5V
Figure 25. 2-Channel Divider with 1 V Scaling (16-Lead SBDIP and PDIP Shown)