HIGH_OUTPUT_600_OHM_LINE_DRIVER

Published:2009/7/1 22:52:00 Author:May | From:SeekIC

The circuit has a floating output, i.e., it behaves like an isolated transfonner winding, with the output amplitude remaining unchanged whether the center or either end of the load is grounded. This is achieved by making Z-out, common mode, infinite. The circuit consists of two current-sources in push-pull. Since each has infinite output Z, the common mode output impedance is also infinite. Connecting a resistor between the noninverting terminals of the op amps reduces the differential Z-out without affecting the Z-common-mode. Since the output is floating, if the load is also floating there is no output ground reference, which results in malfunction. This can be corrected by reducing the common-mode Z slightly. R7 fulfills this function. All resistors should be of close tolerance to give a good balance. The line driver provides +24 dB from ±12 V or + 16 dB from ±6 V supplies.



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