Receiver circuit and amplifier circuit
First Claim
1. A receiver circuit comprising:
- an attenuator that receives a received signal and attenuates the received signal;
a DC level shifter that shifts a DC level of an attenuated signal from the attenuator;
an amplifier section that has frequency characteristics of a band-pass filter and amplifies a signal from the DC level shifter that has been shifted with respect to the DC level; and
a control circuit that controls an attenuation of the attenuator based on a signal output from the amplifier section,the control circuit controlling the attenuation of the attenuator by changing filter characteristics of the attenuator corresponding to an amplitude of the signal output from the amplifier section so that the signal output from the amplifier section has a constant amplitude even when an amplitude of the received signal has changed.
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Accused Products
Abstract
A receiver circuit includes an attenuator that receives a received signal and attenuates the received signal, a DC level shifter that shifts a DC level of an attenuated signal from the attenuator, an amplifier section that has frequency characteristics of a band-pass filter and amplifies a signal from the DC level shifter that has been shifted with respect to the DC level, and a control circuit that controls an attenuation of the attenuator based on a signal output from the amplifier section. The control circuit controls the attenuation of the attenuator by changing filter characteristics of the attenuator corresponding to an amplitude of the signal output from the amplifier section so that the signal output from the amplifier section has a constant amplitude even when an amplitude of the received signal has changed.
15 Citations
20 Claims
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1. A receiver circuit comprising:
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an attenuator that receives a received signal and attenuates the received signal; a DC level shifter that shifts a DC level of an attenuated signal from the attenuator; an amplifier section that has frequency characteristics of a band-pass filter and amplifies a signal from the DC level shifter that has been shifted with respect to the DC level; and a control circuit that controls an attenuation of the attenuator based on a signal output from the amplifier section, the control circuit controlling the attenuation of the attenuator by changing filter characteristics of the attenuator corresponding to an amplitude of the signal output from the amplifier section so that the signal output from the amplifier section has a constant amplitude even when an amplitude of the received signal has changed. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An amplifier circuit comprising:
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a first operational amplifier, an input signal being input to a first input terminal of the first operational amplifier; a second operational amplifier that is a voltage-follower-connected operational amplifier, an output from the first operational amplifier being input to a first input terminal of the second operational amplifier, and an output from the second operational amplifier being input to a second input terminal of the second operational amplifier and a second input terminal of the first operational amplifier; and a gain setting section that sets a gain of the amplifier circuit, when a first bias current that flows through the first operational amplifier is referred to as IB1 and a second bias current that flows through the second operational amplifier is referred to as IB2, the amplifier circuit being provided with frequency characteristics of a band-pass filter by setting the first bias current IB1 to be larger than the second bias current IB2. - View Dependent Claims (9, 10, 11, 12)
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13. An amplifier circuit comprising:
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a first operational amplifier, an input signal being input to a first input terminal of the first operational amplifier; a second operational amplifier that is a voltage-follower-connected operational amplifier, an output from the first operational amplifier being input to a first input terminal of the second operational amplifier, and an output from the second operational amplifier being input to a second input terminal of the second operational amplifier and a second input terminal of the first operational amplifier; and a gain setting section that sets a gain of the amplifier circuit, the second operational amplifier being a rail-to-rail operational amplifier. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification