Patent ID: 6940339
Filing Date: 2005-09-06
Classification: G05F

Abstract:
1. A radio transceiver apparatus comprising: a transmitter including a baseband signal generator, an orthogonal modulator fabricated by two multipliers connected to the baseband signal generator, a variable gain amplifier connected to an output of the orthogonal modulator, an up converter connected to an output of the variable amplifier and a power amplifier connected to an output of the up converter, and a receiver fabricated by a low-noise amplifier, a down converter connected to an output of the low-noise amplifier, a variable gain amplifier connected to an output of the down converter and an orthogonal demodulator including multipliers, at least some of the multipliers, the variable gain amplifier, the up converter, the power amplifier, the low-noise amplifier, and the down converter including a bias generator, the bias generator comprising: a current generator which is configured with a first MOS transistor and a second MOS transistor, and generates a current proportional to mobility of the second MOS transistor; and a current inverter circuit which is supplied with the current and produces the bias current inversely proportional to the mobility, the current generator comprising a voltage adder which includes the first MOS transistor and which adds a voltage, whose temperature dependency is small with respect to the mobility, and a threshold voltage of the first MOS transistor to output a sum voltage, and the second MOS transistor including a source terminal, a gate terminal and a drain terminal, the second MOS transistor receiving the sum voltage between the gate terminal and the source terminal of the second MOS transistor to output the current proportional to the mobility from the drain terminal of the second MOS transistor, and the voltage adder comprising a first current source that outputs a first current whose temperature dependency is small with respect to the mobility, a first resistor producing a voltage whose temperature dependency is small with respect to the mobility when the first current flows through the first resistor, and a second current source which is connected to the first MOS transistor and outputs a second current whose temperature dependency is small with respect to the mobility and which is smaller than the first current, the first MOS transistor generating the sum voltage by adding a gate-source voltage of the first MOS transistor and the voltage produced by the first resistor at the source terminal of the first MOS transistor.