Detailed Description

The following sections describe the tuning methodology

best implemented with a class A amplifier. Other classes

of operation may require significantly different settings.

Supply Decoupling Capacitors

Capacitors C4 and C5 are 0.01µF (±10%) and are used

for minimizing low-frequency noise on the supply.

External Matching Components

The MAX2009 external matching networks at the input

and output of the phase and gain sections consist of

C1, C11, C10, C12, C9, C8, C6, C7, along with some

high-impedance transmission lines. The MAX2010

matching consists of C1, C11, L1, L2, C10, C12, C9, C8,

C6, and C7.

Phase-Tuning Section

Varactors VR1 and VR2 provide fine tuning of the

phase-expansion slope. Resistors R1 and R2 provide a

high-impedance method to inject control voltage on the

varactors. Capacitors C2 and C3 are coupling capaci-

tors that also offset the series parasitic inductance of

the chip and PC board. If phase-slope fine tuning is not

required in the user’s application, then only C2 and C3

to ground are necessary.

Gain and Phase Controls

The MAX2009/MAX2010 controls can provide real-time

software-controlled distortion corrections as well as set-

and-forget tuning by setting the expansion starting

point (breakpoint) and the rate of expansion (slope).

The gain and phase breakpoints are adjustable over a

20dB input power range. The phase expansion slope is

variable from 0.3°/dB to 2.0°/dB and can be adjusted

for a maximum of 24° of phase expansion. The gain

expansion slope is variable from 0.1dB/dB to 0.6dB/dB

and can be adjusted for a maximum of 7dB gain

expansion.

Phase-Expansion Breakpoint

sponds to a breakpoint input power range of 3.7dBm to

23dBm. In order to achieve optimal performance, the

phase-expansion breakpoint of the MAX2009/

MAX2010 must be set to equal the phase compression

point of the PA.

Control pin PBRAW should be shorted to the PBEXP

output pin for most applications. Driving PBRAW direct-

ly allows for additional control such as obtaining phase

compression for some and/or all the input power

sweep. Resistor R3 allows the option of driving PBRAW

with a low-impedance voltage, which overrides the

PBEXP output voltage.

Phase-Expansion Slope

The phase-expansion slope of the MAX2009/MAX2010 is

controlled by the PF_S1, PF_S2, PD_CS1, and PD_CS2

pins. Most applications require PF_S1 and PF_S2 to be

driven identically, and therefore they are shorted on layer

4 of the PC board. The phase-expansion slope of the

MAX2009/MAX2010 must also be adjusted to equal the

opposite slope of the PA’s phase-compression curve.

Gain-Expansion Breakpoint

The G_BP input voltage range of 0.5V to 5.0V

corresponds to a breakpoint input power range of -3dBm

to 23dBm. In order to achieve the optimal performance,

the gain-expansion breakpoint of the MAX2009/

MAX2010

must

be

set

to

equal

the

gain-

compression point of the PA. The G_BP control has a

minimal effect on the small-signal gain when operated

from 0.5V to 5.0V.

Gain-Expansion Slope

Both G_CS and G_FS pins have an input voltage range

0.1dB/dB to 0.6dB/dB. The slope is set to maximum

tion to properly setting the breakpoint, the gain-expan-

sion slope of the MAX2009/MAX2010 must also be

adjusted in order to compensate for the PA’s gain com-

pression. The slope should be set using the following

equation:

MAX20XX_SLOPE =

where:

MAX20XX_SLOPE = MAX2009/MAX2010 gain section’s

slope in dB/dB.

PA_SLOPE = PA’s gain slope in dB/dB, a negative

number for compressive behavior.

Unlike with the G_BP pin, modifying the gain-expansion

slope bias on the G_CS pin causes a change in the

part’s insertion loss and noise figure. For example, a

smaller slope caused by G_CS results in a better inser-

tion loss and lower noise figure.

−

+

PA SLOPE

PA SLOPE

_

_

1

MAX2009/MAX2010 Evaluation Kits

_______________________________________________________________________________________

3

PIN (J5)

VOLTAGE (V)

G_BP

1.2

G_FS

5

G_CS

1.0

Table 2. Gain Section Control Voltages