Pantech PG-1400, Руководство по обслуживанию

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PG-1400 Service Manual
issues. However, since the Aero II transceiver has no requirement for BBIC support of complex dc
offset compensation, it is able to interface to all of the industry leading baseband ICs.
The receive (RX) section integrates four differentialinput low noise amplifiers (LNAs) supporting the
E-GSM 900 (925–960 MHz), DCS 1800 (1805–1880 MHz) bands. The LNA gain is controlled with the
LNAG bit.
A quadrature image-reject mixer downconverts the RF signal to a low intermediate frequency (IF).
The mixer output is amplified with an analog programmable gain amplifier (PGA) that is controlled
with the AGAIN bits. The quadrature IF signal is digitized with high resolution analog-to-digital
converters (ADCs). The ADC output is downconverted to baseband with a digital quadrature local
oscillator signal. Digital decimation and FIR filters perform digital filtering, and remove ADC
quantization noise, blockers, and reference interferers. The response of the FIR filter is
programmable to a flat passband setting and a linear phase setting. After filtering, the digital output is
scaled with a PGA, which is controlled with the DGAIN bits.
The LNAG, AGAIN, and DGAIN register bits should be set to provide a constant amplitude signal to
the baseband receive inputs.
Digital-to-analog converters (DACs) drive differential I and Q analog signals onto the BIP, BIN, BQP,
and BQN pins to interface to standard analog-input baseband ICs.
The receive DACs are updated at 1.083 MHz and have a first-order reconstruction filter with a 1 MHz
bandwidth. No special processing is required in the baseband for dc offset compensation. The receive and
transmit baseband I/Q pins are multiplexed together in a 4-wire interface (BIP, BIN, BQP, and BQN). The
common mode level at the receive I and Q outputs is programmable with the DACCM bits, and the fullscale level
is programmable with the DACFS bits.
4.2.3.2 Receiver Part
ASM (Antenna Switch Module)
ASM consists of Tx filter, having an antenna port, and dual configuration with the transmitting path
isolated from the receiving path. A signal receives from the antenna of frequency band which is
942.5
±
17.5MHz for GSM900 bands, 1842.5
±
37.5 MHz for DCS bands and transmits it to the saw
filter for each band. The Tx filter passes through the output signals of frequency band that is
897.5MHz
±
17.5MHz for GSM950 bands, 1747.5
±
37.5 MHz for DCS bnads from the power
amplifier and transmits it to the antenna. The maximum insertion loss is about 1.5 dB for the
receiving bands at 25
o
C and about 1.5 dB for the transmitting bands at 25
o
C.
SAW Filter (
BPF / Band select filter
)
The
F501
filter is for the GSM900 band signals which range 942.5
±
17.5MHz with low insertion
loss. And
F2
filter passes the DCS bands that cover 1842.5 ± 37.5 MHz. These filters degrade
other band signals with high passing loss of 30~60 dB. The EGSM, and DCS’s maximum insertion
loss is 2.6 dB
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