PMB2240

Functional Description

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.

Features

- Transmitter with I/Q modulator
- Direct I/Q modulation
- Generation of orthogonal carriers with possibility of phase adjust with external resistors at OFF1/OFF2
- 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

Applications

- 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