CX74037 Datasheet, PDF (2/11 Pages) Conexant Systems, Inc – Transmit RF IC for TDMA or AMPS Applications

CX74037
Transmit RF IC for TDMA or AMPS Applications
PCS RF SAW
PCS LO Cell LO
IF LO IN
PCS-TDMA
RF Out
Cell RF Out
CX74037
TX RFIC
22
VCC
I Data
IF Select
Band Select
÷2
PULL En
PA Driver En
VGA En
Q Data
Vvga
Cell RF SAW
LPF or BPF
Figure 2. CX74037 Functional Block Diagram
101103A-2_080900
Technical Description
The CX74037 is a TDMA transmitter for the 800 MHz and 1900
MHz bands. It also can be used as an FM transmitter in AMPS
mode at the 800 MHz band. A band select command chooses
between the 800 MHz band and the 1900 MHz band. A mode
select command chooses between TDMA and AMPS mode.
The chip consist of an I/Q modulator, IF LO input buffer, IF VGA,
two upconverters for the 800 MHz and 1900 MHz bands, and
two PA drivers for the 800 MHz and the 1900 MHz bands.
I/Q Modulator. The I/Q modulator converts the incoming I/Q
signal to an IF signal using one of the two local oscillator inputs.
This signal is fed directly to the VGA amplifier.
Variable Gain Amplifier. The VGA is a differential amplifier that
receives its signal from the I/Q modulator, amplifies it, and then
is taken off-chip to be filtered before routing it to the
upconverter. A dynamic range of 90 dB is available on the
amplifier. A DC voltage of 0.2 to 2.5 V is needed to control the
gain of the amplifier.
Upconverters. The 800 MHz and 1900 MHz upconverters
receive the IF signal from the VGA amplifier. Each upconverter
requires an external LO controlled by an external Phase Locked
Loop (PLL). The band select command switches between the
800 MHz and the 1900 MHz bands.
PA Drivers. Two PA drivers are included, the 800 MHz driver
and the 1900 MHz driver. Each driver takes its input from the
upconverter after passing through an image rejection filter. The
driver amplifies the signal and sends it to an external PA.
Electrical and Mechanical Specifications ________________
The signal pin assignments and functional pin descriptions are
found in Table 1. The absolute maximum ratings of the
CX74037 are provided in Table 2, the recommended operating
conditions are specified in Table 3. Electrical characteristics for
the CX74037 are shown in Table 4. Table 5 defines the control
signal logic.
Figure 3 provides the package dimensions for the 48-pin, 7x7
LGA package.
ESD Sensitivity
The CX74037 is a static-sensitive electronic device. Do not
operate or store near strong electrostatic fields. Take proper
ESD precautions.
Data Sheet
Conexant Proprietary
Data Subject to Change
Doc. No. 101103A
September 27, 2000