W3011

1 GHz Quadrature Modulator

Data Sheet

September 1999

Features

+ Guaranteed performance at 2.7 V power supply

+ Output power of 3 dBm into 50 Ω load (single-

ended) with 3 V operation

+ Direct RF modulation with or without offset mixer

+ Automatic power control (APC) capability

+ Accurate 90° phase shifter for carrier

+ Double-balanced active mixers minimize carrier

feedthrough (origin offset)

+ Low-current sleep mode

Applications

+ PDC 800 and American digital cellular mobile

terminals

+ Cellular base stations

Description

The W3011 1 GHz Quadrature Modulator is a

monolithic integrated circuit that provides direct

modulation of an RF carrier by I & Q baseband

inputs. It is particularly suited for use in mobile and

handheld cellular telephones designed to the IS-136

(North American 824 MHz to 849 MHz), PDC

(Japan RCR-STD27 889 MHz to 958 MHz), and

other digital personal-communications standards.

The circuit block diagram is shown in Figure 1. From

two LO signals, LOL and LOH, the offset mixer

produces an internal LO signal, which prevents the

external VCOs from being pulled by the large

transmitted signal. The phase shifter splits the LO

signal into two carriers with 90° phase separation

and equal amplitude.

These signals are fed to the in-phase (I) and

quadrature-phase (Q) double-balanced mixers. The

resulting signals are summed and fed into the output

amplifier. This amplifier can provide 0 dBm linear

output power, minimum, into a 50

Ω load.

The output power can be attenuated up to 50 dB by

applying a control voltage to the APC input.

Nominally, the output power is at maximum

A CMOS/TTL-compatible logic input allows the

device to be put into a powerdown mode in which

less than 10 µA of supply current is consumed.

BIAS AND CONTROL

ENABLE

GROUND

∑

φ

EXTERNAL FILTER

OR

DIRECT LO INPUT

APC

–

π/4

+π/4

Q

I

LOL IN

50

Ω

LOH IN

50

Ω

Figure 1. Circuit Block Diagram