622Mbps, Ultra-Low-Power, 3.3V Transimpedance Preamplifier for SDH/SONET

The MAX3665 low-power transimpedance preamplifier for 622Mbps SDH/SONET applications consumes only 70mW at VCC = 3.3V. Operating from a single +3.3V or +5.0V supply, it converts a small photodiode current to a measurable differential voltage. A DC cancellation circuit provides a true differential output swing over a wide range of input current levels, thus reducing pulse-width distortion. The differential outputs are back-terminated with 50Ω per side.

The overall transimpedance gain is nominally 8kΩ. For input signal levels beyond approximately 50µAp-p, the amplifier will limit the output swing to 250mV. The MAX3665's low 55nA input noise provides a typical sensitivity of -33.2dBm in 1300nm, 622Mbps receivers.

The MAX3665 is designed to be used in conjunction with the MAX3676 clock recovery and data retiming IC with limiting amplifier. Together they form a complete 3.3V or 5.0V 622Mbps SDH/SONET receiver.

In die form, the MAX3665 is designed to fit on a header with a PIN diode. It includes a filter connection that provides positive bias for the photodiode through a 1.5kΩ resistor to VCC. The device is available in an 8-pin µMAX® package.

Applications

* PIN Photodiode Preamplifiers and Receivers * Regenerators for SDH/SONET * SDH/SONET Receivers

* +3.3V or +5.0V Single-Supply Operation

* 55nARMS Input-Referred Noise

* 70mW Power Consumption at VCC = 3.3V

* 8kΩ Gain

* 450µA Peak Input Current

* 260ps (max) Deterministic Jitter

* Differential Output Drives 100ΩLoad

* 470MHz Bandwidth