Amplifier system with current-mode servo feedback
First Claim
1. An amplifier apparatus comprising:
- differential inputs disposed to receive a first and second input signal;
a primary differential amplifier having inverting and non-inverting input nodes receiving said first and second input signal through respective first and second impedance elements and providing a main output signal; and
feedback circuitry disposed to sample said main output signal and convey complementary current-mode negative feedback signals to said inverting and non-inverting input nodes.
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Accused Products
Abstract
A system and method for compensating an amplifier apparatus for low frequency and/or DC components of an externally applied input signal as well as for any voltage offsets contributed by the amplifier circuitry. Band-limited servo feedback is applied to predetermined nodes in the forward gain path to null out unwanted signal components, leaving a residual signal that, when amplified, will be centered around ground, so that the full dynamic range of the amplifier system may be utilized. Consequently, the signal-to-noise ratio available at the output of the amplifier system will be maximized. The servo compensation may either operate in continuous time, or it may be held constant once a suitable level of compensation has been established, or it may be adjusted from time to time to accommodate slow variations of the average DC component of the input signal.
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Citations
41 Claims
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1. An amplifier apparatus comprising:
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differential inputs disposed to receive a first and second input signal; a primary differential amplifier having inverting and non-inverting input nodes receiving said first and second input signal through respective first and second impedance elements and providing a main output signal; and feedback circuitry disposed to sample said main output signal and convey complementary current-mode negative feedback signals to said inverting and non-inverting input nodes. - View Dependent Claims (17)
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2. An amplifier apparatus comprising:
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differential inputs disposed to receive a first and second input signal; a primary differential amplifier having inverting and non-inverting input nodes receiving said first and second input signal through respective first and second impedance elements and providing a main output signal; and feedback circuitry disposed to sample said main output signal and convey complementary current-mode negative feedback signals to said inverting and non-inverting input nodes, wherein said current-mode feedback signals are each servo feedback signals having the same low-pass characteristic. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 31, 32, 33, 34)
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10. An amplifier apparatus comprising:
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a first input differential amplifier disposed to receive a first input signal at its non-inverting input and output a first intermediate output signal; a second input differential amplifier disposed to receive a second input signal at its non-inverting input and output a second intermediate output signal; a primary differential amplifier disposed to receive at its non-inverting input said first intermediate output signal conveyed through a first impedance element and to receive at its inverting input said second intermediate output signal conveyed through a second impedance element, and provide a main output signal at its output node; and feedback circuitry disposed to sample said main output signal and convey a first negative feedback signal to said inverting input of said first input differential amplifier, and a second negative feedback signal to said inverting input of said second input differential amplifier. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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30. A signal detection and amplification system comprising amplifier apparatus having:
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differential inputs disposed to receive a first and second input signal; a primary differential amplifier receiving said first and second input signal and providing a main output signal; and feedback circuitry disposed to sample said main output signal and convey complementary current-mode negative feedback signals to said differential inputs.
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35. A method for compensating an output of an amplifier system comprising:
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integrating said output to generate a feedback control signal; controlling a pair of complementary current mode feedback signals with said feedback control signal; connecting said pair of complementary current mode feedback signals to input nodes of a primary amplifier wherein said input nodes are connected through impedance elements to differential inputs of said amplifier system. - View Dependent Claims (36, 37, 38, 39)
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40. An amplifier apparatus comprising:
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a primary amplifier providing a main output signal; and feedback means disposed to sample said main output signal and convey complementary current-mode negative feedback signals to said primary amplifier.
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41. An amplifier apparatus comprising:
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a primary amplifier providing a main output signal; and feedback means disposed to sample said main output signal and convey complementary current-mode negative feedback signals to said primary amplifier, wherein a DC value of said main output signal is substantially equal to a reference potential.
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Specification