MAX2022ETX 查看數據表（PDF） - Maxim Integrated

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MAX2022ETX

High-Dynamic-Range, Direct Upconversion 1500MHz to 2500MHz Quadrature Modulator

Maxim Integrated 

High-Dynamic-Range, Direct Upconversion

1500MHz to 2500MHz Quadrature Modulator

up to 2VP-P differential (common-mode input equals 0V).

The wide input bandwidth allows for direct interface with

the baseband DACs. No active buffer circuitry between

the baseband DAC and the MAX2022 is required.

The I and Q signals directly modulate the 0° and 90°

LO signals and are upconverted to the RF frequency.

The outputs of the I and Q mixers are combined

through a balun to a singled-ended RF output.

Applications Information

LO Input Drive

The LO input of the MAX2022 requires a single-ended

drive at a 1500MHz to 2500MHz frequency. It is inter-

nally matched to 50Ω. An integrated balun converts the

singled-ended input signal to a differential signal at the

LO buffer differential input. An external DC-blocking

capacitor is the only external part required at this inter-

face. The LO input power should be within the -3dBm

to +3dBm range.

COMP Pin

The COMP pin is used to provide additional lowpass fil-

tering to the bias circuit noise. An external capacitor

can be used from the COMP pin to ground to reduce

the close-in noise of the modulator. For UMTS, connect-

ing a 22pF capacitor from the COMP pin to ground is

recommended to filter out noise and frequency offsets

above 3.5MHz. For GSM, connecting a 1nF capacitor

from COMP to ground is recommended for filtering out

noise and frequency offsets above 600kHz.

Baseband I/Q Input Drive

The MAX2022 I and Q baseband inputs should be dri-

ven differentially for best performance. The baseband

inputs have a 50Ω differential input impedance. The

optimum source impedance for the I and Q inputs is

100Ω differential. This source impedance will achieve

the optimal signal transfer to the I and Q inputs, and the

optimum output RF impedance match. The MAX2022

can accept input power levels of up to +12dBm on the I

and Q inputs. Operation with complex waveforms, such

as CDMA or WCDMA carriers, utilize input power levels

that are far lower. This lower power operation is made

necessary by the high peak-to-average ratios of these

complex waveforms. The peak signals must be kept

below the compression level of the MAX2022. The input

common-mode voltage should be confined to the -2V to

+1.5V DC range.

The MAX2022 is designed to interface directly with

Maxim high-speed DACs. This generates an ideal total

transmitter lineup, with minimal ancillary circuit elements.

Such DACs include the MAX5875 series of dual DACs,

and the MAX5895 dual interpolating DAC. These DACs

have ground-referenced differential current outputs.

Typical termination of each DAC output into a 50Ω load

MAX5895

DUAL 16-BIT INTERP DAC

50Ω

BBI

FREQ

50Ω

MAX2022

RF MODULATOR

50Ω

I/Q GAIN AND

OFFSET ADJUST

LO

0°

∑

90°

50Ω

50Ω

50Ω

FREQ

BBQ

50Ω

Figure 1. MAX5895 DAC Interfaced with MAX2022

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