Ultrasound imaging or other use variable input impedance...

Details Ultrasound imaging or other use variable input impedance... Ultrasound imaging or other use variable input impedance...

2005-12-15

2009-08-04

Choe, Henry K (Department: 2817)

Amplifiers

With semiconductor amplifying device

Including differential amplifier

C330S254000

Reexamination Certificate

active

07570112

ABSTRACT:
A preamplifier has a variable input impedance. The input impedance is tailored with the signal level to maintain a more optimal performance. The input impedance is varied by at least two amplifiers connected in parallel. Each amplifier has a different input impedance. By controlling the bias currents to the amplifiers, the contribution to the input impedance of the parallel amplifiers is controlled. Gradual variation in input impedance may be obtained by gradual variation in relative contribution by the different amplifiers.

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U.S. Appl. No. 11/198,740, filed Aug. 5, 2005.
U.S. Appl. No. 11/197,929, filed Aug. 5, 2005.

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