Microsemi UM9552 Datasheet

FeaturesFeatures

IP3 (dBm)

580 Pleasant St.
Watertown, MA 02472
PH: [phone]
FAX: [phone]

UM9552

• Low Frequency Attenuator

• HF/LF Band Operation

• Long Lifetime (70 µµs typ.)

• Very Low Distortion (IP3 @ 455 KHz = < 60 dBm)

Description

The UM9552 is a very long minority carrier

lifetime (70 µµs 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.

PIN DIODE

ATTENUATOR

TYPICAL POWER LEVEL vs FORWARD BIAS CURRENT

40

f1 = F +/- 1 KHz

f2 = F +/- 1 KHz

35

30

25

POWER LEVEL/TONE (dBm)

20

15

1 102 3 4 5 6 7 8

If NEEDED TO OBTAIN AN IM3 OF - 60 dBc (mA)

500KHz

250KHz

TAU = 0.1 ms

150KHz

70

65

60

55

50

45

Electrical Specifications (25°C)

Test Min. Typ. Max. Units Conditions

Diode Resistance R

Capacitance C
Reverse Current I
Carrier Lifetime ττ

S

T

R

50 70

IP3 50 60 dBm Power in = 0 dBm / Tone

Thermal Resistance 1.0

MSCO867B 11-30-98 DSW UM9552 <B>(34943)

18.0

2.0
.25 0.4

ΩΩ
ΩΩ
ΩΩ

F = 455 KHz, If = 1 mA
F = 455 KHz, If =10 mA
F = 455 KHz, If = 100 mA

15 20 pF F = 1 MHz, 100 V

10

µµA

µµs

VR = 50 V
If =10 mA / 100 V

F1 = 454 KHz F2 = 456 KHz
Circuit Drawing #B14433

°°C / W 25°°C Stud Temperature

UM9552

TYPICAL RS vs FORWARD BIAS CURRENT

1000

100

10

Rs (Ohms)

1

.1

.01 .1 1 10 100

If (mA)

TYPICAL I-V CURVE

2

10

1

10

0

10

-1

10

-2

10

-3

10

If [AMPERES]

-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

150 oC
125 oC
100 oC
75 oC
50 oC
25 oC

Vf [VOLTS]

0.0

-0.5

-1.0

-1.5

TCVf [mV/oC]

-2.0

-2.5

-3.0

-3

10

TYPICAL TCVf vs If

-2

10

-1

10

If [AMPERES]

DELTA
125 oC

0

10

1

10

MSCO867B 11-30-98 DSW UM9552 <B>(34943)