MAX2601-MAX2602 MAXIM [Maxim Integrated Products], MAX2601-MAX2602 Datasheet - Page 4

• Manufacturer Part Number: MAX2601-MAX2602
• Description: 3.6V, 1W RF Power Transistors for 900MHz Applications
• Manufacturer: MAXIM [Maxim Integrated Products]

3.6V, 1W RF Power Transistors
for 900MHz Applications
Figure 1. Test Circuit
The MAX2601/MAX2602 are high-performance silicon
bipolar transistors in power-enhanced, 8-pin SO pack-
ages. The base and collector connections use two pins
each to reduce series inductance. The emitter con-
nects to three (MAX2602) or four (MAX2601) pins in
addition to a back-side heat slug, which solders direct-
ly to the PC board ground to reduce emitter inductance
and improve thermal dissipation. The transistors are
intended to be used in the common-emitter configura-
tion for maximum power gain and power-added
efficiency.
The MAX2602 includes a high-performance silicon
bipolar RF power transistor and a thermally matched
biasing diode that matches the power transistor’s ther-
mal and process characteristics. This diode is used to
create a bias network that accurately controls the
power transistor’s collector current as the temperature
changes (Figure 2).
The biasing diode is a scaled version of the power tran-
sistor’s base-emitter junction, in such a way that the
current through the biasing diode is 1/15 the quiescent
collector current of the RF power transistor. Supplying
the biasing diode with a constant current source and
connecting the diode’s anode to the RF power transis-
tor’s base ensures that the RF power transistor’s quies-
cent collector current remains constant through
4
_______________Detailed Description
_______________________________________________________________________________________
T1, T2 =
RF
V
BB
IN
L1 =
0.1 F
2pF
COILCRAFT A05T INDUCTOR, 18.5nH
1", 50 TRANSMISSION LINE ON FR-4
MAX2601/MAX2602
Current Mirror Bias
1000pF
T1
(MAX2602 only)
1000pF
5
12pF
100nH
4
5
24
temperature variations. Simply tying the biasing diode
to the supply through a resistor is adequate in most sit-
uations. If large supply variations are anticipated, con-
nect the biasing diode to a reference voltage through a
resistor, or use a stable current source. Connect the
biasing diode to the base of the RF power transistor
through a large RF impedance, such as an RF choke
(inductor), and decouple to ground through a surface-
mount chip capacitor larger than 1000pF.
Figure 2. Bias Diode Application
Q1
2, 6, 7
BACKSIDE
SLUG
V
CC
1
L1
8
R
BIAS
1000pF
10pF
C
1000pF
BIAS
RF
RF
IN
C
C
0.1 F
IN
T2
V
CC
2pF
RF
Q2
C
V
CC
C
OUT
RF
OUT