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US 6,441,688 B1Granted
Single-to-differential buffer amplifier
AssigneeMotorola, Inc.
InventorsSin Kai Henry Lau, Glenn Watanabe
Life of this patent
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Abstract
A radio frequency single to differential buffer amplifier provides a 180 degree phase difference between two output signals by using a current mirroring circuit and using different referencing on the two output signals. Fine adjustment on the phase of the two output signals can be done by adjusting a phase adjustment device embedded in a cascode amplifier. High input power handling capability is accomplished by class AB operation on two input transistors in the amplifier.
Claims17
A radio frequency single to differential buffer amplifier comprising:
- a radio frequency input signal;
- a matching circuit coupled to the radio frequency input signal which preserves the radio frequency input signal;
- an output circuit which provides a first output signal and a second output signal wherein the first and second output signals have approximately a same amplitude and are approximately 180 degrees out of phase over a high frequency range of operation and is independent of the input power, wherein the output circuit comprises a first current path which provides the first output signal;
- and a second current path which provides the second output signal, and wherein the first current path comprises:
- a transistor coupled to the matching circuit for preserving the radio frequency input signal;
- a current mirror coupled to the transistor of the first current path which supplies a complementary signal having similar characteristics as the radio frequency input signal;
- and
- a load device coupled to the current mirror and to ground which develops the first output signal.
5 more elements
A radio frequency single to differential buffer amplifier comprising:
- a radio frequency input signal;
- a matching circuit coupled to the radio frequency input signal which preserves the radio frequency input signal;
- an output circuit which provides a first output signal and a second output signal wherein the first and second output signals have approximately a same amplitude and are approximately 180 degrees out of phase over a high frequency range of operation and is independent of the input power, wherein the output circuit comprises a first current path which provides the first output signal;
- and a second current path which provides the second output signal, and wherein the second current path comprises:
- a first transistor coupled to the matching circuit for preserving the radio frequency input signal;
- a second transistor coupled to the first transistor for preserving the radio frequency input signal;
- a load device coupled to the second transistor of the second current path and to a bias voltage which develops the second output signal;
- and
- a phase adjustment device coupled to the first transistor and the second transistor of the second current path for adjusting a phase of the second output signal.
6 more elements
Dependencies are inferred from the claim text.