MSCO867B 11-30-98 DSW UM9552 <B>(34943)
UM9552
Features
Features
Low Frequency Attenuator
HF/LF Band Operation
Long Lifetime (70
s typ.)
Very Low Distortion (IP3 @ 455 KHz = < 60 dBm)
Description
Electrical Specifications (25
C)
Test
Min.
Typ.
Max.
Units
Conditions
Diode Resistance R
S
18.0
F = 455 KHz, I
f
= 1 mA
2.0
F = 455 KHz, I
f
=10 mA
.25
0.4
F = 455 KHz, I
f
= 100 mA
Capacitance C
T
15
20
pF
F = 1 MHz, 100 V
Reverse Current I
R
10
A
V
R
= 50 V
Carrier Lifetime
50
70
s
I
f
=10 mA / 100 V
IP3
50
60
dBm
Power in = 0 dBm / Tone
F1 = 454 KHz F2 = 456 KHz
Circuit Drawing #B14433
Thermal Resistance
1.0
C / W
25
C Stud Temperature
1
10
2
3
4
5
6
7
8
If NEEDED TO OBTAIN AN IM3 OF - 60 dBc (mA)
15
20
25
30
35
40
POWER LEVEL/TONE (dBm)
45
50
55
60
65
70
IP3 (dBm)
TYPICAL POWER LEVEL vs FORWARD BIAS CURRENT
500KHz
250KHz
150KHz
TAU = 0.1 ms
f1 = F +/- 1 KHz
f2 = F +/- 1 KHz
580 Pleasant St.
Watertown, MA 02472
PH: (617) 926-0404
FAX: (617) 924-1235
PIN DIODE
ATTENUATOR
The UM9552 is a very long minority carrier
lifetime (70
s typical) PIN DIODE that has been
developed for low HF or LF Band Attenuator
Applications. They have been evaluated for attenuator
linearity and distortion characteristics in a Bridge Tee
Attenuator Circuit at 455 KHz (the common intermediate
frequency for AM transmitters and receivers). When the
UM9552's are used as the two variable resistors in the
Bridged Tee Circuit, the Third Order Intermodulation
Products are below -60 dBc with 0 dBm input power
over an attenuation range of 4 dB to 30 dB.
These thicker, longer lifetime PIN diodes exhibit
a more linear forward biased resistance (R
S
) vs forward
bias current (If) relationship, which greatly simplifies the
design of the driver circuits that supply the bias
currents over the specified attenuation range. This task
is simplified if the low attenuation range is truncated
and the few dB are compensated by commercially
available, inexpensive 4 to 6 dB gain blocks.
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