Description

FCC ID: KBCIX260-PROAC555

Operational Description

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FCCID_453790

1XRTT AC555 Detailed Circuit Description Document #: 2110622 Revision: C ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C Page 2 of 14 Table of Contents 1 General ..................................................................................................3 1.1 Purpose ........................................................................................................... 3 1.2 Scope............................................................................................................... 3 1.3 Glossary of terms............................................................................................. 3 1.4 References ....................................................................................................... 3 1.5 Revision history ............................................................................................... 3 2 Circuit Description .................................................................................4 2.1 LOGIC ............................................................................................................ 4 2.1.1 Block Diagram......................................................................................... 4 2.1.2 MSM5105................................................................................................ 4 2.1.3 FPGA/ASIC............................................................................................. 5 2.1.4 DC to DC Converter ................................................................................ 6 2.1.5 Voltage Regulators................................................................................... 6 2.1.6 Audio Circuitry ........................................................................................ 6 3 Aircard 555 Radio ..................................................................................7 3.1 RF Circuit, Cellular and PCS Transceiver....................................................... 7 3.2 Specifications .................................................................................................. 7 3.3 Architecture..................................................................................................... 9 3.4 Frequency Generation Unit ........................................................................... 11 3.4.1 19.2 MHz Reference Oscillator .............................................................. 11 3.4.2 LO Buffer Amplifiers............................................................................. 11 3.5 Transmitter.................................................................................................... 11 3.5.1 Power Amplifier .................................................................................... 12 3.5.2 Automatic level control.......................................................................... 12 3.5.3 Duplexer and Diplexer ........................................................................... 12 3.6 Receiver......................................................................................................... 12 3.7 Baseband Audio Processing – Transmitter and Receiver ............................... 13 3.8 Tuning Functions........................................................................................... 13 3.8.1 TRK_LO_ADJ....................................................................................... 13 3.8.2 PA_ON_PCS, PA_ON_CELL ............................................................... 13 3.8.3 TX_AGC_ADJ ...................................................................................... 13 3.8.4 I_OFFSET, Q_OFFSET......................................................................... 13 3.8.5 SY_SENDB, SY_SDATA, SY_SCLK................................................... 13 3.8.6 SBCK, SBST, SBDT ............................................................................. 14 3.9 Power Supply................................................................................................. 14 ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C Page 3 of 14 1 General 1.1 Purpose This document details the logic circuitry of the AC555 modems. 1.2 Scope This document covers only the logic portion of the product. 1.3 Glossary of terms 1XRTT – Qualcomm’s CDMA2000 Standard. ASIC – Application-Specific Integrated Circuit FPGA – Field Programmable Gate Array PCMCIA – Personal Computer Memory Card International Association PWM – Pulse Width Modulated TCXO – Temperature Controlled Oscillator USB – Universal Serial Bus 1.4 References Ref. # Doc. # Document title R-1 MSM5105 Device Specification R-2 RFT3100 Device Specification R-3 IFR3000 Device Specification 1.5 Revision history Revision Date Author Summary of changes ECO # A Nov 24, Phillips Original 2000 B Dec 7, Phillips Modified document based on feedback. 2000 C Aug 2, D. Kwong Added RF section 2001 T. McKeen ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C Page 4 of 14 2 Circuit Description 2.1 LOGIC 2.1.1 Block Diagram CWE Bypass Circuit 3.3V Radio Voltages Regulators Voltage 2.5V/3.0V Detector RX I Data (4) RX Q Data (4) RX_AGC_ADJ FLASH/RAM 2.5V/ IFR3000 I_OFFSET 16M/4M - 16 Bit3.0V DC/DC Q_OFFSET SLEEP_N (soft NVRAM) LNA_RANGE0 LNA_RANGE1 Serial Bus (3) NDIS P Radio C TCXO M TCXO TRK_LO_ADJ MSM5105 X ilinx FPGA TCXO_ENABLE C CIS I A 16550 TX I Signal TX I Signal_N TX Q Signal LED TX Q Signal_N RFT3100 TX_AGC_ADJ SYNTH_LOCK IDLE_N PA_ON Audio Audio PA_R0 PA_R1 Conditioning Connector 2.1.2 M S M 5 1 0 5 ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C P a g e5 o f 1 4 T h e M S M 5 1 0 5 i s a Q u a lco m m ’s A S I C . I t ’s the lower n ocost f theversio MSM5100. B o t h c h i p s a r e t h e 1 X R T T v e r s i o n o f t h e M S M 3 1 0 0 . T h e M S M 3 1 0 0 is not compatible w ith the M S M 3 0 0 0 , w h i c h w e u s e d o n t h e A irC a r d 5 1 0 . T h e M S M 5 1 0 5 c o n t a i n s a n A R M 7 m icro controller, a D S-c P ,h aann n8e l A / D c o n v e r t e r , v o i c e c o d e c , 1 ,U2S B p o r t U A R T p o rts, and some other glue logic. T h e M S M 5 1 0 5 u s e s t h e F L A S H t o s t o r e i t s f i r m w a r e a n d t h e R A M to store variables. The FLASH and RAM are combined in one stacked chip part. This type of part was c h o s e n t o s a v e s p a c e o n t h e P C B . T h e F LsAuSp H p owr t ill“read w h ile w r ite” operation, w h ich allow s t h e d a t a t h a t u s e d t o b e s t o r e d i n t h e e x t e r n a l E E P R O M t o m o v e i n t o t h e F L A S H . T h e F L A S H R O M h a s 1 6 M e g a b its of storage arranged in 2M b y 1 6 b it w o r d s . T h e F L A S H is sectorized so that it can bederased p r o g r aanmmed in blocks. The RAM is a 4 M e g a b i t p a r t a r r a n g e d i n 2 5 6 k b y 8 1 6 b i t w o r d s . O n e q u a r t e r o f t h e F L A S H i s r e s e r v e d t o r e p l a c e t h e f u n c t i o n o f t h e E E P R O M . The special bank can also store data s u c h a s t h e C I S a n d F P G A p r o g r a m m i n g i n f o r misa t not i o n used that when the CDM A engine is running. T h e M S M 5 1 0 5 r u n s o f f the radio’s 1 9 . 6 8 M H z T C X O c lock. It has a secondary 32.768kHz clock, which it uses when in sleep mode to wake up the TCXO clock. T h e M S M 3 0 0 0 h a s t w o i n t e r f a c e s t o o t h e r p a r t su oit.f t The h e c ifirst r c is the interface to t h e F P G A / A S I C . T h e F P G A / A S I C is attached to the M S M 5 1 0 5 t h r o u g h its m e m o r y b u This allow s t h e F P G A / A S I C t o b e p a r t o f t h e M S M 5 1 0 5 ’s m e m o r y m a p . T h e s e c o n d interface is to the radio. The transm it and receive are signals sent from the M S M 5 1 0 5 ’s DSP to the radio as I and Q data. The receive data is digital but the transmit data is analog. This is different from the A irC a r d 5 1 0 , w h i c h w a s e n t i r e l y d i g i t a l . T h e o t h e r control signals are on/off signals such as thel i nPA_O e a n dNP W M signals such as T X _ A G C _ A D J. PW M signals once properly filter can server as D / A o u t p u t s . 2.1.3 F P G A /A S I C The logic interface chip is an FPG A d u r i n g d e v e l o p m e n t a n d A S I C d u r i n g p r o d u c t i o n . I s e r v e s t h e p u r p o s e o f P C M C I A i n t e r f a c e . T h e Pterface CM C I A allow in s t h e m o d e m t o b e p l u g g e d i n t o a n d p o w e r e d o n i n a n y P C M C I A s o c k e t . T h e F P G A / A S I C p r o v ides the CIS information the PCMCIA host needs. This information is programmed into the A S I C b y t h e M S M 5 1 0 5 u p o n b o o t u p . T h e F P G A / A S I C a l s o550 c o nserial t a i n s port a 16 emulator and an NDIS interface w ith dual 256 by 16bit synchronous FIFOs. The 16550 port is for FAX and circuit sw i t c h e d c o n n e c t i o n s . T h e N D I S i s f o r p a c k e t c o n n e c t i o n s and status information. ? 1 9 9 9-2001 Sierra W ireless Inc. The contents of this page arec tsubje to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C Page 6 of 14 2.1.4 DC to DC Converter The modem has one DC-to-DC converter, which is uses to convert 5.0V down to 3.3V. This allows the modem to work in both 5.0V and 3.3V PCMCIA sockets. It is capable of delivering 1Amp of continuous current at an efficiency of over 90%. There is a voltage detector, which senses if the input voltage is 3.3V. If it is, then the DC/DC converter is switched off and the bypass FET is switched on. 2.1.5 Voltage Regulators The modem has multiple low-dropout regulators. One is used to power the MSM5105 and the Xilinx FPGA. The others are there to provide various voltages to the radio. The regulators also have the addition functions of providing isolation and volt-dip protection. 2.1.6 Audio Circuitry The AirCard555 is capable of doing voice calls. For this reason connections are made to the MSM5105’s built-in codec to provide microphone input and speaker output on the audio connector. ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C Page 7 of 14 3 Aircard 555 Radio 3.1 RF Circuit, Cellular and PCS Transceiver The transceiver is a spread spectrum O-QPSK full duplex modem capable of operating in the AMPS (824 – 894 MHz) and PCS (1850 – 1990 MHz) bands. Max output power is +23.0 dBm as outlined in the IS2000 and IS-98D CDMA standard with a max current draw of 800 mA while transmitting at this level. Channel spacing for the above bands is 30 KHz for AMPS and 50 KHz for PCS. 3.2 Specifications Aircard 555 will comply with the requirements of IS-2000 and IS-98-D. General Table 1: Power Supply DC Power Supply 3.3V +/- 5% in series with a source impedance of 0.5 ohms (minimum of 3.0V under load) Table 2: Transceiver Specifications AMPS PCS Transmit Frequency 824 to 848 MHz 1850 to 1910 MHz Receive Frequency 869 to 893 MHz 1930 to 1990 MHz Channel Spacing 30 KHz 50 KHz Modes Receive, Full Duplex Transmit Modulation O-QPSK, BW = 1.25MHz Performance Bandwidth 25 MHz 60 MHz Frequency Stability +/- 2.5 ppm over all environmental conditions Transmitter Transmit Output Power (conducted) 200 mW (23 dBm), adjustable to .010 uW (-50 dBm) @ +3.3Vdc Transmitter Spurious Outputs Per FCC Part 22, 24 ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C Page 8 of 14 Receiver Sensitivity (conducted) -104 dBm for 1% FER (AMPS) -104 dBm for 1% FER (PCS) ACPR PCS -42 dBc @ 1.25MHz AMPS -42 dBc @ 885KHz Spurious Emissions Per FCC 15 Table 4: Environmental Specifications The product must, as a minimum, meet all PCMCIA specifications (release 2.01, section 3.6) except for operating temperatures as shown below: Operation Temperature -30 to +65 deg. C Humidity 95% non-condensing Vibration Per PCMCIA spec 15G peak, 10-2000 Hz (non-operating) ESD Per PCMCIA spec Shock Per PCMCIA spec Drop 30 in. onto non-cushioning vinyl covered concrete Physical Specifications Aircard 555 will be a type II PCMCIA card with minimal (<15mm) or no extension other than the antenna. ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C Page 9 of 14 Antenna Specifications The antenna is a removable hinged flip-up antenna that is capable of withstanding a drop onto vinyl from 30 inches (per PCMCIA spec) while in any extended position without damage (while out of slot). The antenna, when not in use, will fold down or rotate. The RF output of the Aircard 555 will have a 50 ohm coaxial connection to support remotely mounted antennas and test connections. The gain of the antenna will be in the range of 0 to –1.0 dBi. 3.3 Architecture A block diagram of the radio section is given below in Figure 2. The Aircard 555 wireless modem consists of two main sections, i.e. the Control Logic Circuits and the Radio Transceiver Circuits. Qualcomm’s MSM5105 in the logic section controls all functions in the transceiver. It is responsible for programming the synthesizer, RF power selection, enabling and disabling the transmitter and receiver sections, and performing electronically tuned adjustment. The transceiver uses a single synthesizer for both the transmitter and receiver. The operation of the synthesizer is described in section 2.4, Frequency Generation Unit. The synthesizer uses high-side injection for both the AMPS and PCS bands. The synthesizer produces a frequency that is 183.6 MHz above our desired RX frequency (RX first LO) and 263.6 MHz above our desired TX frequency for PCS (228.6 MHz for AMPS). The transmitter and receiver are described in more detail in the appropriate sections. ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C Page 10 of 14 Figure 2. Radio Block Diagram RXQD3 1960 MHz SAW CMY-210 RXQD2 LNA LNA RXQD1 RXQD0 RF IF LO RXID3 RXID2 183.6 MHz XTAL Filter RXID1 882 MHz SAW IF Switch RXID0 IFR IOFFSET QOFFSET CHIPX8 SBCK SBST TXCO SBDT SLEEP RF IF LO IF LO Buffer RX PCS CMH82 SY_SENB IF SY_SDATA 1900MHz TX SY_SCLK AUX_OUT Coupler LNA_RANGE 6dB Splitter RF Synthesizer TCXO RX LO Buffer TRK_LO_ADJ 900MHz SI4133-X1 19.2 MHz TCXO RX TCXO Buffer CELL TX BUF_TCXO Coupler Power Detector PWRDBK PA3.3V TX_I_P TX LO Buffer PA_BIASCELL TX_I_N TX_Q_P TX_Q_N CELL PA CELL 837 MHz SAW RFT DAC_IREF PA3.3V PA_BIASPCS SBCK SBDT SBST PCS PCS PA TX_AGC_ADJ PA_MODE 1880 MHz SAW PA_ON_PCS PA_ON_CELL ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C Page 11 of 14 3.4 Frequency Generation Unit The frequency generation unit (FGU) generates the local oscillator signals for the receiver and the transmitter. It consists of a 3 phased locked loops that produces a synthesized signal in the range of 1052.61 to 1077.61 MHz for AMPS, 2113.6 to 2173.6 MHz for PCS, and a dedicated IF LO of 367.2 MHz (2xIF) all contained within Silicon Lab’s Si4133-X1 synthesizer. The desired frequency is programmed by the MSM via the synthesizer control lines (SY_SENDB, SY_SDATA, SY_SCLK). This LO signal is routed to the transmitter where it is downconverted by mixing with a AMPS or PCS TX IF (283.6 and 228.6 MHz respectively) modulated signal to produce our transmit carrier frequency. It is also routed to the receiver mixer where it downconverts receive signals into the first IF of 183.6 MHz. The FGU also supplies an IF frequency of 367.2 MHz to the IFR3000 subsystem where it is frequency divided by two providing our second LO. 3.4.1 19.2 MHz Reference Oscillator The Reference Oscillator produces a 19.2 MHz output sine wave signal. It has digital temperature compensation that provides frequency stability of +/- 2.5 ppm over the temperature range of -30 deg. C. to +80 deg. C. Total frequency stability over temperature, voltage and load variation is +/ 0.3 ppm. The reference oscillator feeds the SI4133-X1 synthesizer chip, MSM5105, RFT3100 and IFR3000. 3.4.2 LO Buffer Amplifiers The output of the synthesizer (RF section) is split via a 6dB resistive splitter and fed into two LO buffers (RX and TX). These signals are amplified by the buffers to increase its output level providing enough LO drive to the cellular and PCS mixers. The IF LO buffer’s output is fed to the IFR3000. 3.5 Transmitter The transmitter produces an output frequency in the range of 824 to 849 MHz AMPS and 1850 to 1910 MHz PCS, with channel assignments as per the AMPS and PCS frequency allocation specifications. The transmit chain consists of the RFT3100, cellular and PCS saw filters, power amplifiers, power detectors, duplexers and a diplex filter. The majority of the transmit duties are performed by Qualcomm’s RFT3100 O-QPSK IQ modulator and PA driver chip. This chip consists of 2 differential IQ modulators, onboard IF synthesizer, an upconverter, cellular and PCS PA drivers, and integrated automatic level control circuit. The output of the FGU is mixed with the output of the modulator to produce our desired transmit carrier in the desired band of operation. It is further ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C Page 12 of 14 processed by filtering and amplification before being applied to the duplexer, diplexer and antenna. 3.5.1 Power Amplifier The PA amplifies the transmit signal to produce 200mW of RF power before being applied to the duplexer. The PA’s gain can be switched from low power mode to high power mode by utilizing the PA_MODE switch, large signal gain is increased by 6 dB. 3.5.2 Automatic level control A high Z resistive power coupler is used to tap the output of the PA which is then fed Schottky diode for power detection. The result is fed to one of the MSM’s ADC in which the MSM uses accordingly to maintain our desired output. 3.5.3 Duplexer and Diplexer The RF output of the PA is fed to the duplexer, which combines the transmitter and receiver sections to use one antenna port. The duplexer also provides additional bandpass filtering for the transmitter and receiver. To separate the AMPS and PCS bands a diplexer is used before the antenna. 3.6 Receiver The receiver is a single conversion super heterodyne type, with an IF of 183.6 MHz. Receive signals coupled into the antenna passes through the diplexer and fed to the desired bands duplexer before being fed to their respective RX front ends. For PCS the output of the duplexer is fed to the first LNA it is then filtered by SAW bandpass filter and then fed to the second LNA. From this point the output of the second LNA is fed to a downconverter. The receive signal is downconverted to an IF of 183.6 MHz before going the IF switch. For AMPS, the receive chain is very similar to that of the PCS chain, the LNA stages and mixer stage are handled by a single chip (CMH82) rather than discretely. The local oscillator for this both mixers are provided by the FGU. The downconverted signal is fed to a IF switch. This is where the AMPS and PCS receive chains common point in the circuit. The switched signal is then bandpass filtered by a 183.6 MHz SAW filter and then fed into the IFR3000. This IC first mixes our 183.6 MHz IF signal with a IF LO of 183.6 MHz (generated by dividing 367.2 MHz FGU IF signal) giving us ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C Page 13 of 14 baseband data. This signal further undergoes a series of amplifiers, limiters and serial to parallel shift registers before being applied to MSM5105. 3.7 Baseband Audio Processing – Transmitter and Receiver Baseband data signals to the radio are buffered, amplified and level shifted before being applied to the transmit modulator. Transversely, a demodulated receive signal is fed to the MSM5105 processor for decoding. 3.8 Tuning Functions All tuning functions in the transceiver are performed electronically. The tuning voltages are controlled by the MSM5105 with its onboard digital-to-analog converters. The radio’s tuning functions are described below. 3.8.1 TRK_LO_ADJ Centering of the synthesizer reference oscillator is achieved by adjusting its DC bias (via the TRK_LO_ADJ) to the crystal. 3.8.2 PA_ON_PCS, PA_ON_CELL Used to switch the internal PA drivers of the RFT3100 to desired band of operation. 3.8.3 TX_AGC_ADJ TX_AGC_ADJ controls the RF power at the output of RFT3100 device. 3.8.4 I_OFFSET, Q_OFFSET Used to adjust the balance between the I and Q lines of the IFR3000 to give us orthoganality. 3.8.5 SY_SENDB, SY_SDATA, SY_SCLK Control lines for the Si4133-X1 synthesizer, used to program the three synthesizers to operate within their desired frequency range. ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.

SIERRA WIRELESS INC. Document #: 2110622 Revision: C Page 14 of 14 3.8.6 SBCK, SBST, SBDT This is the serial bus interface (SBI) control lines used to program the IFR3000 and RFT 3100. 3.9 Power Supply The Aircard 555 radio draws its power from the host computer through the PCMCIA interface. PC_VIN, +5.0Vdc is filtered directly out of the PCMCIA connector and then used to supply power to the transmitter and receiver. VBAT is further regulated down to +3.0Vdc using three separate integrated circuit regulators to provide RX_POW, TCXO_POW, TX_POW PA_BIAS and PA_3.3V, which in turn powers the receiver, FGU, and part of the transmitter respectively. Each regulator has its own individual control pin so it can be turned on and off independently. ? 1999-2001 Sierra Wireless Inc. The contents of this page are subject to the confidentiality information on page one.


Document Created: 2004-07-06 15:36:15
Document Modified: 2004-07-06 15:36:15
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