Low voltage operational amplifier having a substantially full range output voltage
First Claim
1. A low voltage line driver circuit having a substantially full range output voltage relative to a power supply voltage range, said output voltage provided by an output stage having a first transistor of a first conductivity type coupled between a power supply voltage terminal and an output terminal and having a second transistor of a second conductivity type coupled between the output terminal and a reference voltage terminal, said line driver circuit maintaining an output quiescent current substantially at a predetermined value, comprising:
- input means coupled to the output stage for providing first and second control signals to the first and second transistors, respectively, to provide the output voltage in response to a differential between first and second input voltages; and
quiescent current control means coupled to both the input means and the output stage, for receiving first and second mirror currents from the first and second transistors and mirroring first and second compensation currents to the input means to adjust the output quiescent current in response to deviation from the predetermined value.
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Accused Products
Abstract
A power amplifier particularly useful as a line driver operating at low power supply voltages is provided. An input portion comprising a differential input configuration is coupled to an output stage having a P-channel MOS transistor connected in series with an N-channel MOS transistor between two power supply voltage terminals. A control portion is coupled to both the input portion and the output stage for providing first and second control signals to the output portion. The control portion regulates the output quiescent current at a predetermined value independent of signal amplification provided by the input portion. The output signal can swing substantially between two power supply voltage potentials.
17 Citations
9 Claims
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1. A low voltage line driver circuit having a substantially full range output voltage relative to a power supply voltage range, said output voltage provided by an output stage having a first transistor of a first conductivity type coupled between a power supply voltage terminal and an output terminal and having a second transistor of a second conductivity type coupled between the output terminal and a reference voltage terminal, said line driver circuit maintaining an output quiescent current substantially at a predetermined value, comprising:
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input means coupled to the output stage for providing first and second control signals to the first and second transistors, respectively, to provide the output voltage in response to a differential between first and second input voltages; and quiescent current control means coupled to both the input means and the output stage, for receiving first and second mirror currents from the first and second transistors and mirroring first and second compensation currents to the input means to adjust the output quiescent current in response to deviation from the predetermined value. - View Dependent Claims (2, 3, 4, 5)
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6. An amplifier circuit having a wide output voltage range in relation to a power supply voltage range for both low and high power supply voltage potentials, comprising:
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an input stage having a first differential input pair of transistors, a load coupled to the first pair of transistors, and a current source coupled to the first pair of transistors for providing a source current to the first pair of transistors; first and second intermediate stages coupled in parallel to the input stage for providing first and second control signals, respectively; an output stage having two transistors of opposite conductivity type coupled in series for providing an output signal in response to the first and second control signals, the two output stage transistors conducting an output quiescent current having a substantially constant predetermined value when no output load is coupled to the output stage; and output quiescent control means coupled to the input stage, the first and second intermediate stages and the output stage, said control means biasing a second differential input pair of transistors by mirroring the output quiescent current in each of the two transistors of the output stage to the control means, said control means mirroring first and second compensation currents to the first and second intermediate stages to adjust the output quiescent current in response to deviation from the predetermined value. - View Dependent Claims (7, 8)
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9. A method of providing an amplifier having a wide output voltage range in relation to a power supply voltage range for both low and high power supply voltage potentials, comprising the steps of:
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providing an input stage with a first differential input pair of transistors, a load coupled to the first pair of transistors, and a current source coupled to the first pair of transistors for providing a first predetermined current to the first pair of transistors; coupling first and second intermediate stages in parallel to the input stage for providing first and second control signals, respectively; coupling two transistors of opposite conductivity in series between terminals for receiving the high and low power supply voltage potentials, said two transistors receiving the first and second control signals, respectively, and providing an output signal in response thereto, and conducting a substantially constant output quiescent current of predetermined value when no output load is coupled to the two transistors; coupling control means to the input stage, the first and second intermediate stages and the two transistors of opposite conductivity for biasing a second differential input pair of transistors by mirroring the predetermined output quiescent current in each of the two transistors of opposite conductivity to the control means; and mirroring first and second compensation currents to the first and second intermediate stages to adjust variations of the output quiescent current in response to deviation from the predetermined value.
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Specification