Description
The HSP50307 is a mixed signal burst QPSK Modulator for upstream CATV Applications. The HSP50307 demultiplexes and modulates a serial data stream onto an RF Carrier centered between 8 and 15MHz. The signal spectrum is shaped with α = 0.5 root raised cosine (RRC) digital filters. On-chip filtering limits spurs and harmonics to levels below -35dBc during transmissions. The output power level is adjustable over a 40dB range in 1dB steps. The maximum differential output level is +62dBmV into 75Ω. A transmitter inhibit function disables the RF output outside the burst interval. The differential output amplifier int7-erfaces to the cable via a transformer.

Features
• 256 KBPS Data Rate and 128 KBPS Baud Rate
• Burst QPSK Modulation
• Programmable Carrier Frequency from 8MHz to 15MHz With a Frequency Step Size of 32kHz
• α = 0.5 Root Raised Cosine (RRC) Filtering For Spectrum Shaping
• On-Board Synthesizer
• Programmable Output Level From 22 to 62dBmV in 1dB Steps
• Programmable Charge Pump Current Control
• 62dBmV Differential Output Driver for 75Ω Cable

Applications
• Burst QPSK Modulator
• HSP50307EVAL1 Evaluation Board Is Available