GENERAL DESCRIPTION
The Quadrature Phase Shift Keying (QPSK) transmitter IC is a monolithic bipolar IC dedicated to quadrature modulation of the I and Q signals. It includes:
• Two double balanced mixers
• A balanced voltage controlled oscillator (VCO) with 0 to 90 degrees signal generation for modulation
• A phase locked loop (PLL) for IF frequency control
• A conversion mixer
• A PLL for RF frequency control
• A gain controlled output amplifier
• A 3-wire bus and an output buffer. Two PLLs are incorporated, the first PLL includes:
• A fixed main divider
• A crystal oscillator and its programmable reference divider
• A phase/frequency detector, combined with a fixed charge pump.

The second PLL includes:
• A divide-by-four preamplifier
• A 12-bit programmable divider
• A crystal oscillator and its programmable reference divider
• A phase/frequency detector, combined with a programmable charge pump which drives the tuning amplifier, including 30 V output.

FEATURES
• Programmable gain
• PLL controlled carrier frequency
• 3-wire transmission bus
• 5 V supply voltage.

APPLICATIONS
• QPSK modulation.