Pantech PG-1210 Service Manual

Also see for PG-1210: User manual

Pantech PG-1210 Service Manual Manual pdf 16 page image

PG-1210 Service ManualAnd F503 filter passes the PCS bands that cover 1960±30MHz. These filters degrade other bandsignals with high passing loss of 30~60 dB. The EGSM, DCS, and PCS’s maximum insertion loss is2.6 dB4.2.4 Transmit Section4.2.4.1 An Overview of Transmit SectionFig.4-8. Transmitter block diagramThe transmit section consists of an I/Q baseband upconverter, an offset phase-locked loop (OPLL),and two 50 Ω output buffers that can drive an external power amplifier (PA). One output is for theGSM 850 (824–849 MHz) and E-GSM 900 (880–915 MHz) bands and one output is for the DCS 1800(1710–1785 MHz) and PCS 1900 (1850–1910 MHz) bands.The OPLL requires no external filtering to attenuate transmitter noise and spurious signals in thereceive band, saving both cost and power. The output of the transmit VCO (TXVCO) is aconstant-envelope signal that reduces the problem of spectral spreading caused by non-linearity inthe PA. Additionally, the TXVCO benefits from isolation provided by the transmit output buffers. Thissignificantly minimizes any load pull effects and eliminates the need for off-chip isolation networks.A quadrature mixer upconverts the differential in-phase (BIP, BIN) and quadrature (BQP, BQN)baseband signals to an intermediate frequency (IF) that is filtered and which is used as the referenceinput to the OPLL. The OPLL consists of a feedback mixer, a phase detector, a loop filter, and a fullyintegrated TXVCO.Low-pass filters before the OPLL phase detector reduce the harmonic content of the quadraturemodulator and feedback mixer outputs.The transmit I/Q interface must have a non-zero input no later than 94 quarter bits after PDN isasserted for proper operation. If the baseband is unable to provide a sufficient TX I/Q non-zero inputpreamble, then the CWDUR bits can be used to provide a preamble extension.The receive and transmit baseband I/Q pins are multiplexed together in a 4-wire interface (BIP, BIN,BQP, and BQN). In transmit mode, the BIP, BIN, BQP, and BQN pins provide the analog I/Q inputfrom the baseband subsystem. The full-scale level at the baseband input pins is programmable withthe BBG[1:0] bits. The I and Q signals are automatically swapped within the Aero II transceiver when15PANTECH