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A balanced optical receiver front-end suitable for Gbit/s heterodyne detection in coherent optical communication systems is presented. The transimpedance is 70 dB Omega with +or-2 dB ripple over the passband from 2 to 4.4 GHz. The ripple was reduced to +or-0.5 dB within a passband from 2.1 to 4.4 GHz by manual tuning of the circuit. The equivalent input noise spectral density is below 4 pA/ square root (Hz) and the common mode rejection ratio better than 26 dB. Standard commercial photodiodes and packaged components are used, and the circuit is implemented in conventional printed circuit board techniques.