PMB-2240 Siemens, PMB-2240 Datasheet - Page 4

• Manufacturer Part Number: PMB-2240
• Description: GSM Transmitter
• Manufacturer: Siemens

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The PMB2240 is a single-chip transmitter which includes a prescaler for the main oscillator signal and
a fixed frequency PLL for the IF oscillator. The transmitter is designed for use in conjunction with the
single-chip receiver PMB2405 and the CMOS PLL PMB2306.
The RF oscillator signal can be supplied from an external source symmetrically as well as
unsymmetrically. The oscillator signal can be buffered for off-chip use, depending on a separate power
down pin.
There is a prescaler by 64/65 for the RF oscillator signal on chip, which can be used to implement a
PLL together with the PMB2306.
The on-chip fixed-PLL consists of the system clock divider, the IF oscillator signal divider, the phase
detector and the charge pump. The IF oscillator signal divider is driven by the oscillator on the
PMB2405 or by an external discrete VCO.
The two oscillator signals are combined in the transmit mixer, and the image sideband and other
mixing products are suppressed with an external interstage filter. The filtered signal reenters the chip
at the modulator inputs LO/LOX. The modulator generates two orthogonal carriers which are mixed
with the modulation signals I and Q in two Gilbert multipliers. The phase between the two carriers can
be fine-adjusted to 90 ° (orthogonality) by two external resistors at OFF1/OFF2 for best SSB
suppression. The outputs of the Gilbert cells are added and amplified by a linear output stage.
The PMB2240 is designed for digital mobile telephones according to the GSM-Standard. The chip can
also be used for other digital systems and the dual mode system.
As part of the Siemens GSM/DCS chipset the derivatives PMB2245 and PMB2247 are offered for the
DCS 1800 and DCS 1900 frequency range.
Siemens AG
The reproduction, transmission or use of this document is not permitted without express written authority. Offenders will be liable for damages. All
resistors at OFF1/OFF2
Transmitter with I/Q modulator
Direct I/Q modulation
Generation of orthogonal carriers with possibility of phase adjust with external
32dB minimum carrier rejection, 35dB minimum SSB rejection with 1 Vpp I/Q drive level
50dB rejection of third order products with 1 Vpp I/Q drive level
-3dBm output power at 1 Vpp I/Q drive level with 200 Ohms load according testcircuit 1
RF oscillator signal is AC-coupled to internal buffer stage (symmetrical or unsymmetrical)
The RF oscillator-signal is buffered for off-chip use, especially for receiver chip PMB2405.
Prescaler for the RF oscillator signal
Possibility to build RF-PLL with integrated prescaler + PMB2306
Possibility to use the IF oscillator signal from the IF-VCO on PMB2405
Possibility to use external source for IF oscillator-signal
Digital parts of fixed IF frequency PLL (fixed-PLL) for IF-VCO on PMB2405
Supply voltage range from 2.7 V to 4.5 V
P-TQFP-48 package
Temperature range -30° to 85°C
Vector modulated digital mobile cellular systems as GSM, DAMPS, PDC,WLAN etc.
Various modulation schemes, such as PM, PSK, FSK, QAM, QPSK, GMSK etc.
Analog systems with FM and AM modulation
Space and power saving optimizations of existing discrete transmitter circuits
rights, including rights created by patent grant or registration of a utility model or design, are reserved.
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