ml4662 Sirenza Microdevices, ml4662 Datasheet - Page 6

• Manufacturer Part Number: ml4662
• Description: High Performance Signal Source
• Manufacturer: Sirenza Microdevices

ML4622, ML4624
FUNCTIONAL DESCRIPTION
AMPLIFIER
The ML4622, ML4624 have an adjustable Bandwidth
limiting amplifier. Maximum sensitivity is achieved
through the use of a DC restoration feedback loop and
AC coupling the input. When AC coupled, the input DC
bias voltage is set by an on-chip network at about 1.7V.
These coupling capacitors, in conjunction with the input
impedance of the amplifier, establish a high pass filter
with a 3dB corner frequency, f
Since the amplifier has a differential input, two capacitors
of equal value are required. If the signal driving the input
is single ended, one of the coupling capacitors can be tied
to V
CF1 and CF2 create a low pass filter with the corner
frequency determined by the following equation
Note:
6
FIBER OPTIC CABLE
CC
as shown in figure 1.
+5V
If TTL OUT is used, tie GND TTL to unfiltered ground and remove L1. If TTL OUT and ECL outputs are both used, add 3K pulldown resistors at
ECL outputs.
–V
RF
0.1
HFBR
0.1
+V
2416
3
6
f =
–V
H
RF
10
RF
7
f =
L
2
+
4.7
1
4
5
8
2 8
0.01
0.01
4.7µH
4.7µH
L1
L2
2 1600C
V
Figure 1. The ML4622, ML4624 Configured for 20MHz Bandwidth
00 (
0.1
TH
V
V
V
V
ADJ
L
IN
1
IN
REF
1
DC
, at
C + 4pF)
+
–
+
4.7
BIAS
0.1
V
TTL*
CC
THRESH
GND
TTL
REF
GEN
CF1
(1)
(2)
AMP
5pF
V
CC
CF2
+V
RF
The above equation applies when a single capacitor is
tied between CF1 and CF2. When using two capacitors of
equal value (Cap1 from CF1 to V
V
Although the input is AC coupled, the offset voltage
within the amplifier will be present at the amplifier’s
output. This is represented by V
reduce this error a DC feedback loop is incorporated. This
negative feedback loop nulls the offset voltage, forcing
V
CC
OS
LINK DETECT
V
V
OUT
OUT
) the value derived for C should be doubled.
C
to be zero. Although the capacitor on V
TIMER
0.05
+
–
CMP
GND
ECL
–V
RF
ECL+
Figure 2.
ECL–
OS
CC
CMP
TTL
in figure 2. In order to
, Cap2 from CF2 to
*ML4624 ONLY
DC
TTL OUT
CMP ENABLE
TTL LINK MON
is non-
V
OS