MAX2602 Evaluation Kit
4) Connect the same power supply through a separate
lead to the EV kit’s VB terminal.
5) Verify that all the connections are correct to avoid
damaging the transistor or your test equipment.
6) Turn on the 3.6V supply. Note the supply current
with the RF generator off. It should be around
7) Activate the RF signal generator and slowly
increase the generator’s output power to 20dBm. At
this time, the supply current should be about
500mA, and the output power should be 30dBm.
Figure 1 is the schematic for the MAX2602 EV kit as
shipped. The circuit consists of four blocks: power-sup-
ply decoupling, a bias network, and both input and out-
put matching networks. The amplifier built on this board
is biased for class AB operation at 1W of output power,
and provides high efficiency.
Supply Decoupling Circuitry
Capacitors C8 and C10 provide decoupling for VC. The
collector has two separate pins: one for the VC input (con-
nected through choke L2), and one for the RF output.
The most important contact for the MAX2602 is not on
the top of the board; it is the bottom-side emitter con-
tact that is connected to ground. This contact keeps
emitter inductance as low as possible, as excessive
emitter inductance can degrade the performance of
any RF common-emitter amplifier. The bottom-side con-
tact is also the principal path for heat dissipation, and
must be connected to a large ground plane.
Capacitors C5, C9, and C11 provide decoupling for the
bias supply. The transistor’s bias current is set by the
internal biasing diode’s current. This current is set by
the following equation:
The collector current is scaled to the bias current:
IC = 15IB. R3 is used as a jumper. The transistor’s base
is biased through R2 and L1 (a choke). For more infor-
mation on the internal biasing diode’s operation, refer to
the MAX2601/MAX2602 data sheet.
Input Matching Network
The transistor’s RF input does not present a 50
impedance, so a matching network is required for prop-
er operation in a 50
Ω environment. This network con-
sists of capacitor C1 to ground, approximately 1 inch
(or 2.5cm) of the 50
Ω transmission line (T1), a DC-
blocking capacitor (C6), and a shunt capacitor at the
transistor base (C4).
2, 6, 7
Figure 1. MAX2602 EV Kit Schematic