QPSK/BPSK DIGITAL DEMODULATOR

The MC92303 is a coherent digital demodulator for QPSK and BPSK modulated signals utilized in Digital-TV applications according to the EBU defined DVB transmission standard for satellite Set-Top systems or similar. The MC92303 contains all the functionality required to lock onto signals with frequency offsets as large as the baud rate and extract the desired signal from a frequency band with adjacent channel interference and other undesirable signals.

FEATURE Summary
• DVB compliant QPSK/BPSK Coherent Demodulator
• Variable Modulation Rate up to 30 MBaud to work with all present European DVB Channels
• Selectable Input Format (Offset Binary/2’s Complement)
• DC Offset Removal, I/Q-swapping and Input Format Selection in one block
• Decimation Filters for Oversampling Ratios of 2/T, 3/T, 4/T, 6/T, 8/T, 12/T and 16/T
• Half Nyquist Baseband Filters (α=0.35)
• Internal Numerically Controlled Oscillator (NCO)
• Automatic Gain Control (AGC) provided to analog front-end
• Automatic Frequency Control (AFC) to ±Rs (Symbol Rate)
• Clock Synchronization with 1-Bit Σ∆-Converter Output for ADC control
• Programmable Second Order Loop Filters for Carrier Recovery and AGC
• 3-bit Soft Decision output per Symbol with selectable format (Offset Binary/2’s Complement/Sign Magnitude)
• Programmable Sampling Rates of the Digital Sigma-Delta Converters
• < 0.5 dB Implementation Loss from theory
• I2C Programmable Interface
• 0.5µ CMOS Process at 3.3V