Stacked amplifier with diode-based biasing
First Claim
1. An apparatus comprising:
- an amplifier comprising a plurality of transistors coupled in a stack and to receive and amplify an input signal and provide an output signal, and at least one diode having a variable voltage drop operatively coupled in series to a gate of at least one transistor in the stack, each diode provides a variable bias voltage to an associated transistor in the stack and each of the plurality of transistors further biased by a common bias circuit.
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Accused Products
Abstract
Techniques for improving linearity of amplifiers are described. In an exemplary design, an amplifier (e.g., a power amplifier) may include a plurality of transistors coupled in a stack and at least one diode. The plurality of transistors may receive and amplify an input signal and provide an output signal. The at least one diode may be operatively coupled to at least one transistor in the stack. Each diode may provide a variable bias voltage to an associated transistor in the stack. Each diode may have a lower voltage drop across the diode at high input power and may provide a higher bias voltage to the associated transistor at high input power. The at least one transistor may have higher gain at high input power due to the higher bias voltage from the at least one diode. The higher gain may improve the linearity of the amplifier.
42 Citations
25 Claims
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1. An apparatus comprising:
- an amplifier comprising a plurality of transistors coupled in a stack and to receive and amplify an input signal and provide an output signal, and at least one diode having a variable voltage drop operatively coupled in series to a gate of at least one transistor in the stack, each diode provides a variable bias voltage to an associated transistor in the stack and each of the plurality of transistors further biased by a common bias circuit.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. An integrated circuit comprising:
- an amplifier comprising a plurality of metal oxide semiconductor (MOS) transistors coupled in a stack and to receive and amplify an input signal and provide an output signal, and at least one diode-connected MOS transistor having a variable voltage drop operatively coupled in series to a gate of at least one MOS transistor in the stack, each diode-connected MOS transistor provides a variable bias voltage to an associated MOS transistor in the stack and each of the plurality of MOS transistors further biased by a common bias circuit.
- View Dependent Claims (17, 18, 19)
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20. A method of amplifying an input signal, comprising:
- amplifying the input signal with a plurality of transistors coupled in a stack to obtain an output signal; and
generating at least one variable bias voltage for at least one transistor in the stack based on at least one diode having a variable voltage drop operatively coupled in series to a gate of the at least one transistor in the stack and each of the plurality of transistors further biased by a common bias circuit. - View Dependent Claims (21, 22, 23, 24)
- amplifying the input signal with a plurality of transistors coupled in a stack to obtain an output signal; and
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25. An apparatus for amplifying an input signal, comprising:
- means for amplifying the input signal to obtain an output signal, the means for amplifying comprising a plurality of transistors coupled in a stack; and
means for generating at least one variable bias voltage for at least one transistor in the stack, the means for generating comprising at least one diode having a variable voltage drop operatively coupled in series to a gate of the at least one transistor in the stack and each of the plurality of transistors further biased by a common bias circuit.
- means for amplifying the input signal to obtain an output signal, the means for amplifying comprising a plurality of transistors coupled in a stack; and
Specification