Low-power feedforward amplifier
First Claim
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1. A low-power feedforward amplifier, comprising:
- (a) a main amplifier(b) means for comparing a sample of an input signal supplied to said main amplifier with a sample of an output signal from said main amplifier, said comparing means producing an error signal proportional to the difference between said signal samples; and
(c) means for amplifying said error signal and combining the amplified error signal with the main amplifier output signal in opposite phase, whereby distortion and noise products generated by said main amplifier are substantially cancelled, said amplifying and combining means including an error amplifier having a plurality of gain stages which share the same bias current.
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Abstract
A feedforward trunk amplifier having the distortion advantages associated with the feedforward topology while providing significantly reduced power consumption and cost. The trunk amplifier has a discrete preamplifier including active gain and slope control, and a low-power feedforward output stage including a medium-gain, hybrid main amplifier, a high-gain, discrete error amplifier having two gain stages which share the same bias current, and miniature coaxial cable delay lines mounted on the cover of the amplifier housing.
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Citations
38 Claims
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1. A low-power feedforward amplifier, comprising:
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(a) a main amplifier (b) means for comparing a sample of an input signal supplied to said main amplifier with a sample of an output signal from said main amplifier, said comparing means producing an error signal proportional to the difference between said signal samples; and (c) means for amplifying said error signal and combining the amplified error signal with the main amplifier output signal in opposite phase, whereby distortion and noise products generated by said main amplifier are substantially cancelled, said amplifying and combining means including an error amplifier having a plurality of gain stages which share the same bias current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A low-power feedforward amplifier, comprising:
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(a) a main path and a feedforward path, said main path including (1) a main amplifier; (2) a first delay line; and (3) a first directional coupler directly interconnecting said main amplifier and said first delay line; said feedforward path including (1) a second delay line; (2) an error amplifier having two gain stages which share the same bias current; and (3) a second directional coupler directly interconnecting said second delay line and said error amplifier; (b) an input directional coupler directly interconnecting a signal input of said feedforward amplifier, said main amplifier and said second delay line; (c) an output directional coupler directly interconnecting said first delay line, said error amplifier, and a signal output of said feedforward amplifier; and (d) an attenuation network directly interconnecting said first and second directional couplers. - View Dependent Claims (14, 15, 16, 17)
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18. A low-power feedforward amplifier, comprising:
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(a) an active gain and slope control network; and (b) a feedforward stage, said feedforward stage including (1) a main amplifier; (2) means for comparing a sample of an input signal supplied to said main amplifier with a sample of an output signal from said main amplifier, said comparing means producing an error signal proportional to the difference between said signal samples; and (3) means for amplifying said error signal and combining the amplified error signal with the main amplifier output signal in opposite phase, whereby distortion and noise products generated by said main amplifier are substantially cancelled. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A low-power feedforward amplifier, comprising:
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(a) an amplifier housing having a cover; (b) a discrete preamplifier including an active gain and slope control network; and (c) a low-power feedforward output stage, said output stage including (1) a main path and a feedforward path, said main path including (A) a medium-gain, hybrid main amplifier; (B) a first delay line, said first delay line being constructed of stripline and mounted on said cover; and (C) a first directional coupler directly interconnecting said main amplifier and said first delay line; said feedforward path including (A) a second delay line, said second delay line being constructed of stripline and mounted on said cover; (B) a high-gain, discrete error amplifier having two gain stages which share the same bias current; and (C) a second directional coupler directly interconnecting said second delay line and said error amplifier; (2) an input directional coupler directly interconnecting a signal input of said feedforward stage, and main amplifier and said second delay line; (3) an output directional coupler directly interconnecting said first delay line, said error amplifier, and a signal output of said feedforward stage; and (4) an attenuation network directly interconnecting said first and second directional couplers. - View Dependent Claims (32, 33, 34)
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35. A low-power feedforward amplifier, comprising:
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(a) an amplifier housing having a cover; (b) a discrete preamplifier including an active gain and slope control network; and (c) a low-power feedforward output stage, said output stage including (1) a main path and a feedforward path, said main path including (A) a medium-gain, hybrid main amplifier; (B) a first delay line, said first delay line being constructed of miniature coaxial cable and mounted on said cover; and (C) a first directional coupler directly interconnecting said main amplifier and said first delay line; said feedforward path including (A) a second delay line, said second delay line being constructed of miniature coaxial cable and mounted on said cover; (B) a high-gain, discrete error amplifier having two gain stages which share the same bias current; and (C) a second directional coupler directly interconnecting said second delay line and said error amplifier; (2) an input directional coupler directly interconnecting a signal input of said feedforward stage, said main amplifier and said second delay line; (3) an output directional coupler directly interconnecting said first delay line, said error amplifier, and a signal output of said feedforward stage; and (4) an attenuation network directly interconnecting said first and second directional couplers. - View Dependent Claims (36, 37, 38)
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Specification