The MAX3664 low-power transimpedance preamplifier for 622Mbps SDH/SONET applications consumes only 85mW. Operating from a single +3.3V 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 60 per side. The transimpedance gain is nominally 6k. For input signal levels beyond approximately 100Ap-p, the amplifier will limit the output swing to 900mV. The MAX3664's low 55nA input noise provides a typical sensitivity of -33.2dBm in 1300nm, 622Mbps receivers.