PX5524

• 4-channel integrated transimpedance and liming amplifier operates up to 4.25 Gb/s
• 8 uA_PP receiver sensitivity for 10^-12 BER
• Single +3.3V supply dissipating 105 mW per channel
• Individual channel signal detect compares input signal
   strength (OMA) with adjustable threshold
• Global signal detect compares quiescent photocurrent with adjustable threshold
• Squelch automatically disables output when input signal
   strength falls below programmable threshold
• Serial digital interface for controlling channel enable and signal detect features
• Reconfigurable I/O provides access to serial digital interface
   and dedicated channel signal detect outputs
• 250-micron channel pitch matches optical ribbon fiber and photodiode arrays

The growing use of the Internet has created increasingly higher demand for multi-Gb/s I/O performance. The demand for 40+ Gb/s WAN bandwidth fuels the growth of short-reach 10 Gb/s infrastructures within high-end telco and datacom routers, switches, servers and other proprietary chassis-to-chassis links. The Zarlink PX5524 4 Gb/s TIA/LA Receiver is a four-channel TIA/LA optical receiver designed for various 4x4 Gb/s parallel optics and CWDM PMD applications. It consists of a DC-coupled transimpedance amplifier and an AC-coupled differential limiting amplifier.

The transimpedance amplifier PX5524 achieves a nominal 3 GHz bandwidth over a wide range of photodiode input capacitance. Excellent channelto- channel isolation ensures data integrity at the receiver sensitivity limits. A global signal detect circuit provides the photodiode reverse bias voltage supply and senses average photocurrent supplied to the photodiode array.

The transimpedance amplifier PX5524 is AC-coupled internally to a high-gain, high-bandwidth differential limiting amplifier. The limiting amplifier provides a differential back-terminated CML output that can be used to drive 4 Gb/s per channel transceivers or other CML compatible clock and data recovery circuits. The limiting amplifier features an adjustable signal detect circuit that senses optical modulation amplitude (OMA) to provide a received signal indication for each channel.