700MHz to 1200MHz High-Linearity,

SPI-Controlled DVGA with Integrated Loopback Mixer

______________________________________________________________________________________

13

MAX2058/MAX2059*

90

°

DUAL DAC

QUAD AMP

ZERO-IF

MODS/DEMODS

RF DIGITAL VGAs

MAX9491*

VCO + PLL

I

12

Q

12

SPI

LOGIC

31dB

RF OUT

*FUTURE PRODUCTS—CONTACT FACTORY FOR SAMPLES

SPI

CONTROL

LOOPBACK

OUT

(FEEDS BACK

INTO Rx CHAIN

FRONT-END)

Rx

OFF

45, 80,

OR

95MHz

LO

17.5dB

31dB

∑

0

°

MAX5873

MAX4395

MAX2021/MAX2022/MAX2023*

Figure 2. Direct Conversion Transmitter for GSM/EDGE Basestations

The 5 MSBs of the 10-bit word program attenuator A,

and the 5 LSBs of the 10-bit word program attenuator

B. Each bit sets the attenuators to a corresponding

attenuation level. For example, logic-low 0 for bit 5 and

bit 0 of attenuator A and B, respectively, sets both

attenuators at 1dB. 00000 configures both attenuators

for 31dB attenuation and 11111 sets for 0dB attenua-

External Bias

Bias currents for the two-stage amplifier and the loop-

back mixer are set and optimized with external resistors.

Resistor R1 (pin 31) sets the bias current for the input

amplifier, R2 (pin 20) sets the bias current for the output

amplifier, and R3 (pin 40) sets the bias for the loopback

mixer. The external biasing resistor values can be

increased for reduced current operation at the expense

of performance. Contact the factory for details.

Board Layout

The pin configuration of the MAX2058 has been opti-

mized to facilitate a very compact physical layout of the

device and its associated discrete components.

The exposed paddle (EP) of the MAX2058’s thin QFN-

EP package provides a low thermal-resistance path to

the die. It is important that the PC board on which the

MAX2058 is mounted be designed to conduct heat

from the EP. In addition, provide the EP with a low-

inductance path to electrical ground. The EP MUST be

soldered to a ground plane on the PC board, either

directly or through an array of plated via holes.

COMPONENT

VALUE

DESCRIPTION

C1, C4, C10, C13,

C16

0.1µF

Microwave capacitors (0603)

C2, C5, C8, C17

100pF

Microwave capacitors (0402)

C3, C6, C14, C19

47pF

Microwave capacitors (0402)

C7, C18

0.01µF

Microwave capacitors (0402)

C9, C12, C15

1000pF

Microwave capacitors (0402)

C11

3.9pF

Microwave capacitor (0402)

R1

1.2k

Ω

±1% resistor (0402)

R2

3.92k

Ω ±1% resistor (0402)

R3

2.0k

Ω

±1% resistor (0402)

R4

110

Ω

±1% resistor (0402)

T1

2:1

RF transformer (100:50)

Mini-Circuits TC2-1T

U1

—

MAX2058 MAXIM IC

Table 2. Component List Referring to the

Typical Application Circuit