OVERVIEW: iDEN Digital Modulation Technology
The audio section is composed of microphone amplifiers, speaker amplifiers, a voice codec
and a stereo DAC. Previously such functionality was performed with the GCAP/PCAP IC. The
receiver ROADRUNNER portion includes circuitry supporting AGC, receiver sequence
management, signal path anti-aliasing filters, buffer amplifiers, high dynamic range sigma delta data
converters, digital filtering and the RX serial data interface to the baseband processor (previously
part of Tomahawk). The TX portion includes circuitry supporting Pulse Shaping FIR, TX DAC,
Smoothing filters, PA Gain Control DAC, and the TX serial data interface to the baseband processor
(previously part of TOMAHAWK). ROADRUNNER also includes circuitry to support additional
features such as GPS AD, USB, RS232, LEDs, etc.
Finally, the baseband processor utilized by i897 is the Zeus Processor.
1.4 Roadrunner Circuitry
The Roadrunner integrated circuit (IC) provides the following:
• DC distribution
• Audio CODEC and amplifiers
• Control logic for power on/off
• A/D converters for monitoring radio thermistors, battery level, LCD calibration, and the
Photosensor.
• The Roadrunner IC used is a 223 I/O MAP BGA package.
The i897 unit has the following DC distribution:
• SW1 is a BUCK step-down switching regulator set to 1.2 Vdc at 550 mA. It supplies the Zeus core.
• SW2 is an external BUCK switching regulator set to 1.875Vdc at 600mA..
• SW3 is a BOOST switching regulator set to 5.6 Vdc at 200 mA. It supplies Vusb.
• V1-The V1_LDO (2.775Vdc at 200mA) is used to power the camera, LCD and photo sensor in a
Zeus-based platform
• V2 - 2.775 Vdc at 350 mA - will be used to power most of the RF circuits as well as the audio codec
and all audio amps.
•
SW3 is a BOOST switching regulator set to 5.1Vdc at 200mA.
• V4 supplies 2.775 Vdc at 50 mA to the Thermistor Bias (Battery, Board ID) TCXO.
• V_VIB (3Vdc at 200mA) is used as enable for vibrator alert mode. LM2758 (external LED driver)
supplies the vibrator
• External VMMC supplies 2.8Vdc at 200mA for Zeus (Z_VDD_SD) and SD card.
• VSIM supplies 3.0 Vdc at 15 mA to the SIM card
• VHOLD - 1.875 Vdc
• VCO Superfilter is used for the transceiver VCO’s. The SF_OUT supply is intended as the power
supply for the external VCO and the integrated Escort VCO on Sledgehammer. The input for the VCO
superfilter is V2.
The battery supplies Raw_B+ and Filtered_B+. RAW_B+ supplies the RF PA. Filtered_B+ directly supplies
Roadrunner and most of its regulators.
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