Data Sheet
September 1999
W3011
1 GHz Quadrature Modulator
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.
Features
+ Guaranteed performance at 2.7 V power supply
+ Output power of 3 dBm into 50 W 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
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.
+ Double-balanced active mixers minimize carrier
feedthrough (origin offset)
+ Low-current sleep mode
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 W load.
Applications
+ PDC 800 and American digital cellular mobile
terminals
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
(+3 dBm) with VAPC > 2.2 V, and at minimum
(–50 dBm) with VAPC < 0.8 V.
+ Cellular base stations
Description
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.
The W3011 1 GHz Quadrature Modulator is a
monolithic integrated circuit that provides direct
I
LOH IN
BIAS AND CONTROL
VCC
50 W
ENABLE
GROUND
–p/4
LOL IN
50 W
RFOUT
å
f
+p/4
Q
EXTERNAL FILTER
OR
DIRECT LO INPUT
APC
Figure 1. Circuit Block Diagram