LT5528EUF Ver la hoja de datos (PDF) - Linear Technology

Número de pieza

componentes Descripción

Fabricante

LT5528EUF

1.5GHz to 2.4GHz High Linearity Direct Quadrature Modulator

Linear Technology 

LT5528

BLOCK DIAGRA

BBPI 14

V-I

BBMI 16

BBPQ 7

V-I

BBMQ 5

VCC

8 13

LT5528

0°

90°

BALUN

11 RF

1 EN

2469

GND

3

10 12 15 17

5528 BD

LO

GND

APPLICATIO S I FOR ATIO

The LT5528 consists of I and Q input differential voltage-

to-current converters, I and Q up-conversion mixers, an

RF output balun, an LO quadrature phase generator and

LO buffers.

RF

VCC = 5V

C

BALUN

LOMI

LT5528

FROM

Q

LOPI

R1A R1B

R2B R2A

20Ω 23Ω

23Ω 20Ω

BBPI

CM

12pF

R3

R4

12pF

VREF = 0.52V

BBMI

GND

5528 F01

Figure 1. Simplified Circuit Schematic of the LT5528

(Only I-Half is Drawn)

External I and Q baseband signals are applied to the dif-

ferential baseband input pins, BBPI, BBMI, and BBPQ,

BBMQ. These voltage signals are converted to currents and

translated to RF frequency by means of double-balanced

up-converting mixers. The mixer outputs are combined

in an RF output balun, which also transforms the output

impedance to 50Ω. The center frequency of the resulting

RF signal is equal to the LO signal frequency. The LO input

drives a phase shifter which splits the LO signal into in-

phase and quadrature LO signals. These LO signals are then

applied to on-chip buffers which drive the up-conversion

mixers. Both the LO input and RF output are single-ended,

50Ω-matched and AC coupled.

Baseband Interface

The baseband inputs (BBPI, BBMI), (BBPQ, BBMQ) present

a differential input impedance of about 90Ω. At each of the

four baseband inputs, a first-order low-pass filter using 20Ω

5528f

8

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