HA4-2546/883 INTERSIL [Intersil Corporation], HA4-2546/883 Datasheet - Page 16

• Manufacturer Part Number: HA4-2546/883
• Description: Wideband Two Quadrant Analog Multiplier (Voltage Output)
• Manufacturer: INTERSIL [Intersil Corporation]

DESIGN INFORMATION
The information contained in this section has been developed through characterization by Intersil Semiconductor and is for use as
application and design information only. No guarantee is implied.
Application Information
Theory of Operation
The HA-2546 is a two quadrant multiplier with the following
three differential inputs; the signal channel, V
control channel, V
V
fier. The differential voltages of channel X and Y are con-
verted to differential currents. These currents are then
multiplied in a circuit similar to a Gilbert Cell multiplier, pro-
ducing a differential current product. The differential voltage
of the Z channel is converted into a differential current which
then sums with the products currents. The differential “prod-
uct/sum” currents are converted to a single-ended current
and then converted to a voltage output by a transimpedance
amplifier.
The open loop transfer equation for the HA-2546 is:
The scale factor is used to maintain the output of the multi-
plier within the normal operating range of 5V. The scale fac-
tor can be defined by the user by way of an optional external
resistor, R
A), Gain Adjust B (GA B), and Gain Adjust C (GA C). The
scale factor is determined as follows:
The scale factor can be adjusted from 2 to 5. It should be
noted that any adjustments to the scale factor will affect the
AC performance of the control channel, V
operating range of V
The typical multiplier configuration is shown in Figure 1. The
ideal transfer function for this configuration is:
Z
V
+ and V
V
where;
OUT
OUT
SF = 2, when GA B is shorted to GA C
SF
SF
=
= A
EXT
Z
-, to complete the feedback of the output ampli-
1.2 R
GA A and GA C (R
1.2 (R
(V
connected to GA B and GA C (R
, and the Gain Adjust pins, Gain Adjust A (GA
A = Output Amplifier Open Loop Gain
SF = Scale Factor
V
X+
(V
X
, V
EXT
- V
X+
EXT
X
+ and V
Y
X
X-
, when R
- V
, V
is equal to the scale factor voltage.
) (V
+ 1.667k ), when R
2
0
Z
X-
SF
= Differential Inputs
) (V
Y+
- V
X
Y+
EXT
-, and the summed channel,
EXT
Y-
- V
)
is connected between
Y-
is in k )
+ V
)
Z-
- (V
X
, when V
, when V
. The normal input
Z+
EXT
Y
(Continued)
EXT
- V
+ and V
is
Z-
is in k )
)
X
X
< 0V
0V
Y
-, the
HA2546
8-18
The V
is negative there is no signal at the output, i.e. two quadrant
operation. If the V
pin maybe grounded and the V
input.
The V
swing 5V. The V
V
while V
by connecting GA B to GA C. Therefore the transfer equation
simplifies to V
Offset Adjustment
The signal channel offset voltage may be nulled by using a
20k
connecting the wiper to -V. Reducing the signal channel off-
set will reduce V
also be nulled by connecting V
potentiometer which is tied between +V and -V.
Capacitive Drive Capability
When driving capacitive loads >20pF, a 50
ommended between V
(See Figure 1). This will prevent the multiplier from going
unstable.
Power Supply Decoupling
Power supply decoupling is essential for high frequency cir-
cuits. A 0.01 F high quality ceramic capacitor at each supply
pin in parallel with a 1 F tantalum capacitor will provide
excellent decoupling. Chip capacitors produce the best
results due to the close spacing with which they may be
placed to the supply pins minimizing lead inductance.
Adjusting Scale Factor
The HA-2546 two quadrant multiplier may be configured for
many uses. Following are examples of a few typical applica-
tions.
OUT
X-
to complete the feedback loop of the output amplifier
potentiometer between V
Y-
Z-
pin is usually connected to ground so that when V
terminal is usually grounded allowing the V
is grounded. The scale factor is normally set to 2
V
NC
NC
NC
Y
V-
+
OUT
1
2
3
4
5
6
7
8
X
Z+
+
AC feedthrough. Output offset voltage can
-
X
= (V
REF
Y
input is a negative going signal the V
terminal is usually connected directly to
50
X
OUT
V
+
FIGURE 1.
Y
-
) / 2.
and V
X
Z
+
+
-
-
16
15
14
13
12
11
10
YIO
Spec Number
9
X-
Z-
Z+
NC
V
V+
, using V
Adjust pins A and B and
to the wiper of a 20k
1K
pin used as the control
X
+
Z+
50pF
resistor is rec-
as the output
511050-883
V
OUT
Y+
X+
X+
to