CIRCUIT DIAGRAM OF A MOBILE PHOHE
CELLULAR PHONES
An example of multi-mode/multi-band mobile phones with separate RF front end and down converters to IF, which is possibly a shared IF. The component used is the here is a SA1920 from Philips semiconductors, an RF front-end intended to covers the 900 and 1,900MHz wireless bands.
Designed with a 13GHz-fT Bicmos process and requires a 3.75 V dc supply.
It is intended for diverse systems as AMPs, GSM and PCs, without any modulation - specific functions because it covers two bands with many filtering between stages.
The low-band section contains a separate LNA and mixer that cover 869 – to 960MHz RF frequencies with an input IF between 100 and 125 MHZ.
The LNA has a noise figure of 1.7 dB and 17.5dB gain. The mixer has 9.5dB gain and an IIP3 of +5dBm. When cascaded, with a filter between them, the combined noise figure is 2.6dB.
The high – band sections contains an LNA and an image- reject mixer based on Gilbert cells that operate from 1,805 to 1,990MHZ. The two are internally cascaded, and together achieve 4.2 dB noise figure, 23.5dB gain and an IIP3 of 12.5Bm.
The high and low-band lo signals are fed from off-clip (pins 30/31). For the high band, the lo in – phase and quadrature signals are derived by two internal all pass networks. The IF output signals are internally shifted by 90o and recombined to realize image – rejection. Contain a separate broadband mixer block for use in transmitter chain (pin10)
It down converts the transmitted signal using the Lo as the receiver. This enables the transmitted, down converted IF channels (pin2/3) to be used in a closed – loop Cartesian transmitter to improve linearity.
Maxim integrated product (MAX 2338) is an RF front – end clip for mod AMPS/N-CDMA cellular phone or for other systems such as duel – band GSM. Like SA1920, converts RF to IF and contains separate LNA sections for both high (1930 to 1990 MHZ) and low (869 to 892MHZ) Rx band which are fed directly from the duplex following the antenna. The gain of LNA, is IIP3 from +5 to 18dBm. With a high linearity mode for higher power CDMA signals, that can only be switched on when necessary. The mixer uses an off- clip Lo at around 2,150MHZ that can be divided by a factor of two for the lower Band to have a IF of around 183MHZ to be used. The clip operates with a 3V dc supply.
Ref: practical RF CIRCUIT DESIGN FOR MODERN WIRELESS SYSTEM. Volume Ii by ROWAN GILMORE & LEE BESSER
An example of multi-mode/multi-band mobile phones with separate RF front end and down converters to IF, which is possibly a shared IF. The component used is the here is a SA1920 from Philips semiconductors, an RF front-end intended to covers the 900 and 1,900MHz wireless bands.
Designed with a 13GHz-fT Bicmos process and requires a 3.75 V dc supply.
It is intended for diverse systems as AMPs, GSM and PCs, without any modulation - specific functions because it covers two bands with many filtering between stages.
The low-band section contains a separate LNA and mixer that cover 869 – to 960MHz RF frequencies with an input IF between 100 and 125 MHZ.
The LNA has a noise figure of 1.7 dB and 17.5dB gain. The mixer has 9.5dB gain and an IIP3 of +5dBm. When cascaded, with a filter between them, the combined noise figure is 2.6dB.
The high – band sections contains an LNA and an image- reject mixer based on Gilbert cells that operate from 1,805 to 1,990MHZ. The two are internally cascaded, and together achieve 4.2 dB noise figure, 23.5dB gain and an IIP3 of 12.5Bm.
The high and low-band lo signals are fed from off-clip (pins 30/31). For the high band, the lo in – phase and quadrature signals are derived by two internal all pass networks. The IF output signals are internally shifted by 90o and recombined to realize image – rejection. Contain a separate broadband mixer block for use in transmitter chain (pin10)
It down converts the transmitted signal using the Lo as the receiver. This enables the transmitted, down converted IF channels (pin2/3) to be used in a closed – loop Cartesian transmitter to improve linearity.
Maxim integrated product (MAX 2338) is an RF front – end clip for mod AMPS/N-CDMA cellular phone or for other systems such as duel – band GSM. Like SA1920, converts RF to IF and contains separate LNA sections for both high (1930 to 1990 MHZ) and low (869 to 892MHZ) Rx band which are fed directly from the duplex following the antenna. The gain of LNA, is IIP3 from +5 to 18dBm. With a high linearity mode for higher power CDMA signals, that can only be switched on when necessary. The mixer uses an off- clip Lo at around 2,150MHZ that can be divided by a factor of two for the lower Band to have a IF of around 183MHZ to be used. The clip operates with a 3V dc supply.
Ref: practical RF CIRCUIT DESIGN FOR MODERN WIRELESS SYSTEM. Volume Ii by ROWAN GILMORE & LEE BESSER
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