MAX2602 Evaluation Kit

2

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4) Connect the same power supply through a separate

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

100mA.

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.

_______________Detailed Description

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

and Grounding

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.

Biasing

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:

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

Ω

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).

I

=

V

- 0.75V

R1

B

B

R1

430

Ω

R3

0

Ω

T1

T2

L2

18.5nH

C9

0.1

µF

C1

2pF

C5

1000pF

C10

0.1

µF

C8

1000pF

C11

1000pF

C12

1000pF

C6

1000pF

C7

1000pF

L1

100nH

IN

R2

24

Ω

C4

12pF

1

3

8

2, 6, 7

BACK-SIDE SLUG

4

5

C2

2pF

OUT

C3

10pF

U1

Figure 1. MAX2602 EV Kit Schematic