Impedance matched variable gain low noise amplifier using shunt feed-back
First Claim
Patent Images
1. An amplifier, comprising:
- a forward amplifier having an input and an output;
a feedback path coupled across said input and output, including,a feedback amplifier coupled to an impedance; and
wherein a signal output of said feedback amplifier is selectively shunted to ground for low gain applications using a switch.
7 Assignments
0 Petitions
Accused Products
Abstract
The variable gain amplifier includes a forward path that provides the amplifier variable gain, and a feedback path. The feedback path uses a switch that is turned on at low gain levels. The switch taps into the feedback resistor, shunting it to signal-ground and eliminating the feedback mechanism. This ensures that the input impedance seen at the input port does not grow excessively, using part of the feedback resistor as a passive termination at low gain levels. In this way variable gain ranges in excess of 30 dB can be achieved.
-
Citations
15 Claims
-
1. An amplifier, comprising:
-
a forward amplifier having an input and an output; a feedback path coupled across said input and output, including, a feedback amplifier coupled to an impedance; and wherein a signal output of said feedback amplifier is selectively shunted to ground for low gain applications using a switch. - View Dependent Claims (2)
-
-
3. An amplifier, comprising:
-
a forward amplifier having an input and an output; a feedback path coupled across said input and output, including, a feedback amplifier coupled to an impedance; wherein a signal output of said feedback amplifier is shunted to ground for low gain applications using a switch; and wherein said feedback path is differential, and said switch is closed for low gain applications, and shorts a positive component to a negative component of said differential feedback path for low gain applications. - View Dependent Claims (4)
-
-
5. A variable gain differential amplifier, comprising:
-
a differential forward amplifier having a differential input and a differential output; and a differential feedback path coupled across said differential input and said differential output; wherein said differential feedback path is shorted together for low gain applications. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A method of variably amplifying a differential input signal, comprising:
-
receiving a differential input signal at an input terminal; variably amplifying the differential input signal to produce a differential amplified signal at an output; feeding back a portion of the differential amplified signal through a feedback path that is coupled to the input terminal to produce a differential feedback signal; and shorting together components of the differential feedback signal for low gain applications.
-
Specification