TCM4400 Datasheet, PDF (9/72 Pages) Texas Instruments – GSM/DCS BASEBAND AND VOICE A/D AND D/A RF INTERFACE CIRCUIT

1 Introduction
The TCM4400 global system for mobile communication (GSM) baseband RF interface circuit is designed
for GSM 900 and DCS 1800 European digital cellular systems (DCS), and PCS 1900 North America
personal communications systems (PCS). It includes a complete set of functions to perform the interface
and processing of voice signals, generate baseband in-phase (I) and quadrature (Q) signals, and control
the signals between a digital signal processor (DSP) and associated RF circuits.
The TCM4400 includes a second serial interface for use with a microcontroller. Through this interface, a
microcontroller can access all the internal registers that can be accessed through the DSP digital serial
interface. This option is for applications in which part of the L1 software is implemented in the microcontroller.
A 4-pin parallel port is dedicated to the full control of the digital audio interface (DAI) to the GSM system
simulator; the DAI consists of system simulator reset (SSRST) control, clock generation, and rate adaptation
with the DSP.
The voice processing portion of the device includes microphone and earphone amplifiers, analog-to-digital
converter (ADC) and digital-to-analog converter (DAC), speech digital filtering, and a serial port.
The baseband processing portion of the device includes a two-channel uplink path, a two-channel downlink
path, a serial port, and a parallel port. The uplink path performs Gaussian minimum shift keying (GMSK)
modulation, D/A conversion, and has smoothing filters to provide the external RF circuit with I and Q
baseband signals. The downlink path performs antialiasing, analog/digital (A/D) conversion, and channel
separation filtering of the baseband I and Q signals. The serial port allows baseband data exchange with
the DSP, and the parallel port controls precise timing signals.
Auxiliary RF functions such as automatic frequency control (AFC), automatic gain control (AGC), power
control, and analog monitoring are also implemented in the TCM4400. Internal functional blocks of the
device can be separately and automatically powered down with GSM RF windows.
1.1 Features
• Applications Include GSM 900, DCS 1800, and PCS 1900 Cellular Telephones
• 80-Pin TQFP Package
• Single 3-V Supply Voltage
• Internal Voltage Reference
• Extended RF Control Voltages
• Advanced Power Management
• GSM-Digital Audio Interface (DAI)
• MCU and DSP Serial Interface
• Five-Port Auxiliary A/D
• Meets JTAG Testability Standard (IEEE Std 1131.1-1990)
• Baseband Codec-GMSK Modulator with On-Chip Burst Buffer
• Voice Codec Features: Microphone Amplifier and Bias Source, Programmable Gain Amplifiers,
Volume Control, and Sidetone Control
1–1