Patent ID: 7554401
Filing Date: 2009-06-30
Classification: H03F

Abstract:
1. A differential amplifier, comprising: a first amplifier connected to a second amplifier, each of the first and second amplifiers including two active elements connected to each other via a primary part of a transformer, one of the two active elements being connected to a power-supply voltage of the amplifier, the other of the two active elements being connected to a ground terminal of the amplifier, an output power appearing in a secondary part of the transformer, the active element connected to the ground terminal being a NMOS (N-type Metal Oxide Semiconductor) transistor, and the active element connected to the power-supply voltage being a PMOS (P-type Metal Oxide Semiconductor) transistor, the first and second amplifiers each including a signal input unit for transmitting input signals having opposite phases to the two active elements; and the signal input units being configured to transmit input signals having opposite phases to the two active elements which are connected to the ground terminals and the two active elements which are connected to the power-supply voltages of the first and second amplifiers, wherein a ground terminal of the first amplifier is connected to that of the second amplifier, a power-supply voltage of the first amplifier is connected to that of the second amplifier, and a secondary part of a transformer of the first amplifier is connected to that of the second amplifier, such that output signals of the first and second amplifiers are coupled to each other via the secondary part of the transformer.