Ericsson Gmbh

Chris W Angell

Erik L Bengtsson

Aristotele Hadjichristos

Scott R Justice

An input buffer circuit is operable to selectively present either low or high input impedance while maintaining uniform output impedance. The buffer is characterized by first and second amplifier circuits connected in parallel between an input to and an output from the buffer. The amplifiers are individually controlled between enabled and disabled states. When enabled, the first amplifier has low input impedance and predetermined output impedance and the second amplifier has high input impedance and the predetermined output impedance, and when disabled each amplifier has high input and output impedance. To operate the buffer to have low input impedance, the first amplifier is enabled while the second amplifier is disabled. To operate the buffer to have high input impedance, the second amplifier is enabled while the first amplifier is disabled. When an amplifier is disabled, its input and output impedances are sufficiently large that the disabled amplifier does not interfere with operation of the enabled amplifier.

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Raleigh, NC, United States of America

Chris W Angell