FMS6404 Series
Precision Composite Video Output with Sound Trap and Group Delay Compensation
Manufacturer: ON Semiconductor
Catalog
Precision Composite Video Output with Sound Trap and Group Delay Compensation
Key Features
• 7.6 MHz 5th-Order Composite Video Filter
• 14dB Notch at 4.425 MHz to 4.6 MHz for Sound Trap Capable of Handling Stereo
• 50dB Stopband Attenuation at 27 MHz on CV Output
• >0.5dB Flatness to 4.2 MHz on CV Output
• Equalizer and Notch Filter for Driving RF Modulator with Group Delay of -180ns
• No External Frequency Selection Components or Clocks
• <5ns Group Delay on CV Output
• AC-Coupled Input
• AC- or DC-Coupled Output
• Capable of PAL Frequency for CV
• Continuous Time Low-Pass Filters
• <1.4% Differential Gain with 0.7° Differential Phase on CV Channel
• Integrated DC Restore Circuitry with Low Tilt
Description
AI
The FMS6404 is a single composite video 5th-order Butterworth low-pass video filter optimized for minimum overshoot and flat group delay. The device contains an audio trap that removes video information in a spectral location of the subsequent RF audio carrier. The group delay compensation circuit pre-distorts the signal to compensate for the inherent receiver intermediate frequency (IF) filter’s group delay distortion.In a typical application, the composite video from the DAC is AC coupled into the filter. The CV input has DC-restore circuitry to clamp the DC input levels during video synchronization. The clamp pulse is derived from the CV channel.All outputs are capable of driving 2VPP, AC- or DC-coupled, into either a single or dual video load. A single video load consists of a series 75 Ω impedance matching resistor connected to a terminated 75 Ω line. This presents a total of 150 Ω of loading to the part. A dual load would be two of these in parallel, which presents a total of 75 Ω to the part. The gain of the CV signal is 6dB with 1 VPPinput levels. All video channels are clamped during synchronization to establish the appropriate output voltage reference levels.
