Differential gain boosting
First Claim
1. A current source circuit with differential gain boosting, comprising:
- a first current source circuit that is coupled to a first output node, a first sense node, and a second sense node, wherein the first current source circuit is arranged to respond to a first feedback signal from the second sense node;
a second current source circuit that is coupled to a second output node, a third sense node, and a fourth sense node, wherein the second current source circuit is arranged to respond to a second feedback signal from the fourth sense node;
a first follower circuit that is coupled between the first sense node and a fifth sense node, wherein the first follower circuit is arranged to respond to a reference signal from a reference node and also respond to a first sense signal from the first sense node;
a second follower circuit that is coupled between the third sense node and a sixth sense node, wherein the second follower circuit is arranged to respond to the reference signal from the reference node and also respond to a third sense signal that is received at the third sense node; and
a differential amplifier circuit having a first amplifier input, a second amplifier input, a first amplifier output, and a second amplifier output, wherein the first amplifier input is coupled to the fifth sense node, the second amplifier input is coupled to the sixth sense node, the first amplifier output is coupled to the second sense node, and the second amplifier output is coupled to the fourth sense node.
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Accused Products
Abstract
A current source circuit with differential gain boosting is provided. The current source circuit differentially provides first and second currents. The first current is produced by a first cascoded current source, and the second current is produced by a second cascoded current source. Each of the cascoded current sources comprises a current source transistor and a cascode transistor. The current source circuit has high output impedance because a voltage associated with a gate of the cascode transistor of the first cascoded current source and another voltage associated with a gate of a cascode transistor of the second cascoded current source are each forced to an approximately constant voltage by a differential amplifier. The drain voltage of the first and second current source transistors are each servoed to the saturation drain to source voltage of the first current source transistor.
7 Citations
19 Claims
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1. A current source circuit with differential gain boosting, comprising:
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a first current source circuit that is coupled to a first output node, a first sense node, and a second sense node, wherein the first current source circuit is arranged to respond to a first feedback signal from the second sense node; a second current source circuit that is coupled to a second output node, a third sense node, and a fourth sense node, wherein the second current source circuit is arranged to respond to a second feedback signal from the fourth sense node; a first follower circuit that is coupled between the first sense node and a fifth sense node, wherein the first follower circuit is arranged to respond to a reference signal from a reference node and also respond to a first sense signal from the first sense node; a second follower circuit that is coupled between the third sense node and a sixth sense node, wherein the second follower circuit is arranged to respond to the reference signal from the reference node and also respond to a third sense signal that is received at the third sense node; and a differential amplifier circuit having a first amplifier input, a second amplifier input, a first amplifier output, and a second amplifier output, wherein the first amplifier input is coupled to the fifth sense node, the second amplifier input is coupled to the sixth sense node, the first amplifier output is coupled to the second sense node, and the second amplifier output is coupled to the fourth sense node. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A current source circuit with differential gain boosting, comprising:
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a first means for producing that is arranged to provide a first output current to a first output node, and also arranged to provide a first sense signal at a first sense node, wherein the first means for producing is responsive to a second sense signal from a second sense node; a second means for producing that is arranged to provide a second output current to a second output node, and also arranged to provide a third sense signal at a third sense node, wherein the second means for producing is responsive to a fourth sense signal from a fourth sense node, and wherein the first means for producing and second means for producing are arranged in cooperation to produce a first differential output signal via the first output current and the second output currents; a first means for servoing that is configured to servo the first sense signal to a predetermined voltage; a second means for servoing that is configured to servo the third sense signal to approximately the predetermined voltage; and a means for providing that is arranged to provide a second differential output signal to the second and fourth sense nodes in response to the first and third sense signals. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method for differential gain boosting, comprising:
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sensing a first sense signal that is associated with a first sense node, wherein a first current source circuit is configured to produce the first sense signal and a first output current, and wherein the first current source circuit is further configured to be responsive to a second sense signal at a second sense node; sensing a third sense signal that is associated with a third sense node, wherein a second current source circuit is configured to produce the third sense signal and a second output current, the second current source circuit is further configured to be responsive to a fourth sense signal at a fourth sense node, and wherein the first current source circuit and the second current source circuit are arranged in cooperation to produce a first differential output signal via the first output current and the second output current; servoing the first sense signal to a pre-determined voltage; servoing the third sense signal to approximately the pre-determined voltage level; and producing a second differential output signal in response to the first sense signal and the third sense signal, wherein the second differential output signal comprises the second sense signal and the fourth sense signal. - View Dependent Claims (18, 19)
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Specification