MICROSEMI UM9552

580 Pleasant St.
Watertown, MA 02472
PH: (617) 926-0404
FAX: (617) 924-1235
UM9552
Features
•
•
•
•
PIN DIODE
ATTENUATOR
Low Frequency Attenuator
HF/LF Band Operation
Long Lifetime (70 µ s typ.)
Very Low Distortion (IP3 @ 455 KHz = < 60 dBm)
Description
The UM9552 is a very long minority carrier
lifetime (70 µ 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 (RS) 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.
TYPICAL POWER LEVEL vs FORWARD BIAS CURRENT
40
70
f1 = F +/- 1 KHz
f2 = F +/- 1 KHz
65
500KHz
250KHz 150KHz
30
60
25
55
20
IP3 (dBm)
POWER LEVEL/TONE (dBm)
35
50
TAU = 0.1 ms
15
45
1
2
3
4
5
6
7
8
10
If NEEDED TO OBTAIN AN IM3 OF - 60 dBc (mA)
Electrical Specifications (25°C)
Test
Diode Resistance RS
Capacitance CT
Reverse Current IR
Carrier Lifetime τ
IP3
Thermal Resistance
MSCO867B 11-30-98
Min.
50
50
Typ.
18.0
2.0
.25
15
Max.
0.4
20
10
70
60
1.0
Units
Ω
Ω
Ω
pF
µA
µs
dBm
°C / W
Conditions
F = 455 KHz, If = 1 mA
F = 455 KHz, If =10 mA
F = 455 KHz, If = 100 mA
F = 1 MHz, 100 V
VR = 50 V
If =10 mA / 100 V
Power in = 0 dBm / Tone
F1 = 454 KHz F2 = 456 KHz
Circuit Drawing #B14433
25°°C Stud Temperature
DSW UM9552 <B>(34943)
UM9552
TYPICAL RS vs FORWARD BIAS CURRENT
TYPICAL TCVf vs If
1000
0.0
DELTA
125 oC
-0.5
100
TCVf [mV/oC]
Rs (Ohms)
-1.0
10
-1.5
-2.0
1
-2.5
.1
.01
.1
1
10
100
-3.0
10
If (mA)
-3
10
-2
-1
10
If [AMPERES]
10
0
10
1
TYPICAL I-V CURVE
2
10
1
10
150 oC
125 oC
100 oC
75 oC
50 oC
25 oC
If [AMPERES]
0
10
-1
10
-2
10
-3
10
-4
10
-5
10
-6
10
0.0
0.2
0.4 0.6
0.8
1.0
1.2
1.4
1.6 1.8
2.0
2.2
Vf [VOLTS]
MSCO867B 11-30-98
DSW UM9552 <B>(34943)
UM9552
UM9552
MSCO867B 11-30-98
DSW UM9552 <B>(34943)
UM9552
UM9552S
MSCO867B 11-30-98
DSW UM9552 <B>(34943)