Switching amplifiers into and out of circuits with reduced output noise
First Claim
1. An amplifier circuit, comprising:
- an input lead to receive an input signal;
a main amplifier including;
a first stage having a first input coupled to the input lead to receive the input signal, and a first output to provide a first stage output signal; and
a second stage having a second input switchably coupled to the first output to receive the first stage output signal, and a second output to provide an output signal to an output lead of the amplifier circuit; and
a catching amplifier coupled to the second stage during at least one time interval so as to cause a gain of approximately zero to result between the input lead and the output lead during the at least one time interval, the main amplifier being arranged such that the first output is uncoupled from the second input during at least a portion of the at least one time interval.
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Accused Products
Abstract
An insubstantial amount of noise results at the output of a circuit when an output of a primary amplifier is disconnected from and reconnected to the circuit in which is operating. The primary amplifier is placed temporarily in a muting configuration. A secondary amplifier permanently in a muting configuration is connected in parallel with the primary amplifier. The output of the primary amplifier then is disconnected from a circuit node to which it is attached. The primary amplifier may then be taken out of its muting configuration. After, for example, configuring the primary amplifier as a comparator and calibrating its dc-offset voltage, the primary amplifier is placed back into a muting configuration. The secondary amplifier then is disconnected from the primary amplifier. The primary amplifier may subsequently be taken out of muting configuration to resume its normal function in the circuit.
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Citations
25 Claims
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1. An amplifier circuit, comprising:
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an input lead to receive an input signal; a main amplifier including; a first stage having a first input coupled to the input lead to receive the input signal, and a first output to provide a first stage output signal; and a second stage having a second input switchably coupled to the first output to receive the first stage output signal, and a second output to provide an output signal to an output lead of the amplifier circuit; and a catching amplifier coupled to the second stage during at least one time interval so as to cause a gain of approximately zero to result between the input lead and the output lead during the at least one time interval, the main amplifier being arranged such that the first output is uncoupled from the second input during at least a portion of the at least one time interval. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An amplifier circuit, comprising:
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an input lead to receive an input signal; a main amplifier including; a first stage having a first input coupled to the input lead to receive the input signal, and a first output to provide a first stage output signal, and a second stage having a second input switchably coupled to the first output to receive the first stage output signal, and a second output to provide an output signal to an output lead of the amplifier circuit; and a catching amplifier switchably coupled to the output lead of the amplifier circuit to selectively configure the amplifier circuit to have a gain of approximately zero between the input lead and the output lead. - View Dependent Claims (8)
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9. An amplifier circuit, comprising:
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an input lead to receive an input signal; a main amplifier including; a first stage having a first input coupled to the input lead to receive the input signal, and a first output to provide a first stage output signal, and a second stage having a second input switchably coupled to the first output to receive the first stage output signal, and a second output to provide an output signal to an output lead of the amplifier circuit; a catching amplifier switchably coupled to the main amplifier to selectively configure amplifier circuit to have a gain of approximately zero between the input lead and the output lead; and a muting mechanism coupled to the main amplifier to selectively configure the amplifier circuit to have a gain of approximately zero between the input lead and the output lead.
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10. An amplifier circuit, comprising:
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an input lead to receive an input signal; a main amplifier including; a main input coupled to the input lead to receive the input signal, and a main output switchably coupled to an output lead of the amplifier circuit to selectively provide an output signal to the output lead; and a catching amplifier switchably coupled to the output lead of the amplifier circuit to selectively configure the amplifier circuit to have a gain of approximately zero between the input lead and the output lead. - View Dependent Claims (11, 12, 13, 14, 15)
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16. An amplifier circuit, comprising:
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an input lead to receive an input signal; a main amplifier including; a main input coupled to the input lead to receive the input signal, and a main output switchably coupled to an output lead of the amplifier circuit to selectively provide an output signal to the output lead; a catching amplifier switchably coupled to the main amplifier to selectively configure the amplifier circuit to have a gain of approximately zero between the input lead and the output lead; and a muting mechanism coupled to the main amplifier to selectively configure the amplifier circuit to have a gain of approximately zero between the input lead and the output lead.
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17. A method for uncoupling an inter-stage output of an amplifier stage of a main amplifier from an inter-stage circuit node to which the inter-stage output is coupled while maintaining a relatively constant output signal at an output node of an amplifier circuit including the main amplifier, comprising the steps of:
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configuring the amplifier circuit to have a gain of approximately zero between an input of the amplifier circuit and the output node of the amplifier circuit; coupling at least one circuit node of a catching amplifier to at least one of the inter-stage circuit node and the output node of the amplifier circuit, the catching amplifier being configured to provide a gain of approximately zero between the input of the amplifier circuit and the output node of the amplifier circuit; and uncoupling the inter-stage output of the amplifier stage of the main amplifier from the inter-stage circuit node. - View Dependent Claims (18, 19)
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20. A method for coupling an inter-stage output of an amplifier stage of a main amplifier to an inter-stage circuit node while maintaining a relatively constant output signal at an output node of an amplifier circuit including the main amplifier, comprising the steps of:
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configuring the amplifier circuit to have a gain of approximately zero between an input of the amplifier circuit and the output node of the amplifier circuit; coupling the inter-stage output of the amplifier stage of the main amplifier to the inter-stage circuit node; and uncoupling a circuit node of a catching amplifier, which is configured to provide a gain of approximately zero between the input of the amplifier circuit and the output node of the amplifier circuit, from the inter-stage circuit node. - View Dependent Claims (21, 22)
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23. A method for uncoupling an output of a main amplifier from an output node of a circuit while maintaining a relatively constant signal at the output node of the circuit, comprising the steps of:
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configuring the circuit to have a gain of approximately zero between an input of the circuit and the output node of the circuit; coupling an output of a catching amplifier, which is configured to provide a gain of approximately zero between the input of the circuit and the output node of the circuit, to the output node of the circuit; and uncoupling the output of the main amplifier from the output node of the circuit.
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24. A method for coupling an output of a main amplifier to an output node of a circuit while maintaining a relatively constant output signal at the output node of the circuit, comprising the steps of:
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configuring the circuit to have a gain of approximately zero between an input of the circuit and the output node of the circuit; coupling the output of the main amplifier to the output node of the circuit; and uncoupling an output of a catching amplifier, which is configured to provide a gain of approximately zero between the input of the circuit and the output node of the circuit, from the output node of the circuit. - View Dependent Claims (25)
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Specification