AD8013
REV. A
–12–
C2084–18–10/95
PRINTED IN U.S.A.
2:1 Video Multiplexer
Configuring two amplifiers as unity gain followers and using the
third to set the gain results in a high performance 2:1 mux
(Figures 39 and 40). This circuit takes advantage of the very low
crosstalk between Channels 2 and 3 to achieve the OFF channel
isolation shown in Figure 40. This circuit can achieve
differential gain and phase of 0.03% and 0.07° respectively.
V
OUT
V
IN
A
R1
2kΩ
V
IN
B
R3
10Ω
R4
10Ω
R2
2kΩ
R5
845Ω
R6
845Ω
7
6
5
1
14
13
12
2
8
9
10
3
2
3
DISABLE
DISABLE
Figure 39. 2:1 Mux with High Isolation and Low
Differential Gain and Phase Errors
FREQUENCY – Hz
1G1M
CLOSED-LOOP GAIN – dB
100M
–8
–1
–2
–3
–4
–5
–6
–7
–40
–50
–60
–70
FEEDTHROUGH – dB
–80
0
1
2
–30
10M
GAIN
FEEDTHROUGH
Figure 40. 2:1 Mux ON Channel Gain and Mux OFF Channel
Feedthrough vs. Frequency
Gain Switching
The AD8013 can be used to build a circuit for switching between
any two arbitrary gains while maintaining a constant input
impedance. The example of Figure 41 shows a circuit for switching
between a noninverting gain of 1 and an inverting gain of 1. The
total time for channel switching and output voltage settling is
about 80 ns.
6
5
4
1
7
+5V
DIS 1
698Ω 698Ω
15Ω
V
OUT
10
9
3
11
8
–5V
DIS 3
845Ω
1k
845Ω
1k
2k
13
14
12
50Ω
100Ω
V
IN
Figure 41. Circuit to Switch Between Gains of –1 and +1
10
0%
100
90
200ns
500mV
5V
500mV
Figure 42. Switching Characteristic for Circuit of Figure 41
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
14-Lead Plastic DIP (N-14)
14
17
8
0.795 (20.19)
0.725 (18.42)
0.280 (7.11)
0.240 (6.10)
PIN 1
SEATING
PLANE
0.022 (0.558)
0.014 (0.356)
0.060 (1.52)
0.015 (0.38)
0.210 (5.33)
MAX
0.130
(3.30)
MIN
0.070 (1.77)
0.045 (1.15)
0.100
(2.54)
BSC
0.160 (4.06)
0.115 (2.93)
0.325 (8.25)
0.300 (7.62)
0.015 (0.381)
0.008 (0.204)
0.195 (4.95)
0.115 (2.93)
14-Lead SOIC (R-14)
14 8
71
0.3444 (8.75)
0.3367 (8.55)
0.2440 (6.20)
0.2284 (5.80)
0.1574 (4.00)
0.1497 (3.80)
PIN 1
SEATING
PLANE
0.0098 (0.25)
0.0040 (0.10)
0.0192 (0.49)
0.0138 (0.35)
0.0688 (1.75)
0.0532 (1.35)
0.0500
(1.27)
BSC
0.0098 (0.25)
0.0075 (0.19)
0.0500 (1.27)
0.0160 (0.41)
8°
0°
0.0196 (0.50)
0.0099 (0.25)
x 45°
