A bias circuit 22 in a power amplifier 1 is provided with a VBE-controlled voltage source circuit 20 and a Nagata current mirror circuit 21. The Nagata current mirror circuit 21 includes a transistor Tr5 and a transistor Tr6. The transistor Tr5 has its emitter grounded, its base connected to a control input terminal 17 via a resistor R3, and its collector connected to that base via a resistor R4. The transistor Tr6 has its emitter grounded, its base connected to the collector of the transistor T...

Amplifier systems are provided with bias generators that substantially stabilize operating points of system parameters (e.g., drain current and transconductance) over PVT variations, substantially reduce body effects and Early effects, and substantially reduce system output noise. These advantages are realized without significantly increasing system size and/or power consumption.

An amplifier circuit (1) includes an amplifying transistor (QO) and a dc bias circuit (2) for biasing the amplifier transistor (QO) to obtain a conduction angle of at least about 180.degree.. The dc bias circuit (2) includes a self-bias boosting circuit which has a Wilson current-mirror (Q4, Q5, Q6) integrated with a cascode current-mirror circuit (Q2, Q3) to form an extended Wilson current-mirror circuit (Q2-Q6) having an output coupled to a control terminal of the amplifying transistor (QO) by...

There is provided a semiconductor device including a substrate, a device isolation insulating film formed on the substrate, a gate electrode formed on the substrate, a gate wiring layer formed in the device isolation insulating film and connected to the gate electrode, source and drain electrodes arranged on the substrate to face each other via the gate electrode, and an insulating film covering bottom and side surfaces of each of the gate electrode and the gate wiring layer, wherein the gate, s...

An auto-range current mirror circuit has a current sensing circuit, a front and rear stage current mirrors each has an adjustable amplifying rate. The current sensing circuit presets a threshold current and has an input current of the front stage current mirror. The current sensing current compares the input current with a threshold current and then outputs a controlling signal to the front and rear stage current mirrors to adjust a suitable amplifying rate. Therefore, a bias current of the rear...

An amplifier for amplifying a signal which is applied to a signal input having a first pair of transistors (10), which is connected to the signal input and which contains two transistors (10-1, 10-2), currents flowing through the two transistors (10-1, 10-2) which have a specific operating current ratio (m) in relation to one another, a second pair of transistors (4), which is connected to the first pair of transistors (10) and which contains two transistors (4-1, 4-2), currents flowing through ...

An amplifier circuit (1) includes an amplifying transistor (QO) and an impedance-controllable dc bias circuit (2) for biasing the amplifier transistor (QO) to obtain a conduction angle of at least about 180.degree.. The dc bias circuit (2) includes a self-bias boosting circuit having separate current sources (Ibias, Iclass) for independently controlling the output impedance of the dc bias circuit (2) and the quiescent current of the amplifier transistor (QO), and has a Wilson current-mirror (Q4,...

In a high frequency power amplifier circuit that supplies a bias to an amplifying FET by a current mirror method, scattering of a threshold voltage Vth due to the scattering of the channel impurity concentration of the FET, and a shift of a bias point caused by the scattering of the threshold voltage Vth and a channel length modulation coefficient .lamda. due to a short channel effect are corrected automatically. The scattering of a high frequency power amplifying characteristic can be reduced a...

An operational transconductance amplifier (OTA) includes a first, a second and a third differential units, a voltage-to-current converting unit and a current subtraction device. The first and the second differential units receive a differential input voltage and the voltage-to-current converting unit converts it into an output current. The OTA adopts a replica scheme, that is, by copying the first differential unit to generate a third differential unit and then performs a subtraction between the...

A system and method is provided for detecting an over-current condition in a power field-effect transistor (FET). In one embodiment, an over-current detection circuit for detecting an over-current condition in a power FET comprises a current generator circuit operative to generate a reference current and a plurality of matched FETs operative to receive the reference current and provide a reference voltage, the matched FETs being matched to each other and to the power FET. The over-current detect...