ZO-28/F
BIAS DEVICE
Thermal Tracking
GENERAL DESCRIPTION
The ZO-28/F is a bias device designed to work with very high power BiPolar
transistors, operating Class A and AB. It has extremely low source impedance
and high current handling capability. The package may be physically mounted
to the same heat sink as the RF transistor, providing very accurate thermal
tracking.
CASE OUTLINE
55GU
ABSOLUTE MAXIMUM RATINGS
Maximum Power Dissipation @ 25
o
C
Maximum Voltage and Current
BVis
Injector to Supplier Voltage
Is
Supplier Current
Ic
Controller Current
Hfe
Transistor Current Gain - Min
Maximum Temperatures
Storage Temperature
Operating Junction Temperature
40 Watts
35 Volts
3.5 Amps
0.3 Amps
30
- 65 to +150
o
C
+200
o
C
See Case Outline for Connections
ELECTRICAL CHARACTERISTICS @ 25
O
C
SYMBOL
BVsco
BViso
BViss
Hfe
Vcr
CHARACTERISTICS
Supplier - Controller Breakdown
Injector Open
INjector - Supplier Breakdown
Controller Opne
Injector - Supplier Breakdown
Controller Shorted
DC Current Gain
Voltage Drop across Diodes
Thermal Resistance
TEST
CONDITIONS
Ii = 0. Is = 5 mA
Ii = 10 mA
Ii = 50 mA
Ii = 1 A, Vis = 5 Volts
Ii = 0A, Ic = 50 mA
MIN
4
50
90
30
1.34
1.4
1.48
4.37
o
TYP
MAX
UNITS
Volts
Volts
Volts
Volts
C/W
θ
jc
Initial Issue June, 1997
GHz TECHNOLOGY INC. RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE. GHz RECOMMENDS THAT BEFORE
THE PRODUCT(S) DESCRIBED HEREIN ARE WRITTEN INTO SPECIFICATIONS, OR USED IN CRITICAL APPLICATIONS, THAT THE
PERFORMANCE CHARACTERISTICS BE VERIFIED BY CONTACTING THE FACTORY.
GHz Technology Inc. 3000 Oakmead Village Drive, Santa Clara, CA 95051-0808 Tel. 408 / 986-8031 Fax 408 / 986-8120
Z0-28/F
Design of the Z0-28
The Z0-28 consists of three semiconductor elements, a transistor and two diodes. The only additional component
necessary is resistor Rc ( see figure) and the RF filtering necessary with any bias system. The Z0-28 operates as an emitter
follower, which accounts for its very low source impedance. The transistor can be operated from any voltage up to 28
Volts. The Z0-28 is capable of 40 Watts power dissipation, enough for most current and Voltage requirements. The power
transistor's quiescent base Voltage is determined by the value of Rc and the supply Voltage.
The two diodes provide the thermal tracking needed for thermally stable operation. One diode compensates for the RF
transistor's base-emitter junction in the Z0-28. By mounting the Z0-28 in thermal contact with the power transistor, the
other diode can compensate for the power devices base-emitter junction. The diodes are fabricated with the same
technology as the RF power transistor for improved thermal stability.
Ghz Technology Inc. 3000 Oakmead Village Drive, Santa Clara, CA 95051-0808 Tel. 408 / 986-8031 Fax 408 / 986-8120
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