In a wide dynamic range and with constant transconductance (Gm) differential voltage-to-current converter, operating in class AB, essentially comprising two complementary pairs of transistors, respectively of pnp (Q1, Q2) and npn (Q3, Q4) type, and two nominally equal resistors (RE1 and RE2), the emitters of the first pair transistors (Q1, Q2) are connected to the respective ones of dse second pair transistors (Q3, Q4) through the two resistores (E) having equal nominal resistance; a junction is provided between the emitters of the second pair transistors (Q3, Q4); and input voltages (V1 and V2) are respectively applied to the bases of first pair transistors (Q1, Q2), from collectors of which transistor output currents (I1, I2) are taken. Preferably, in this differential voltage-to-current converter, biasing and thermal balancing circuits (VP1, VP2) are connected to the first (Q1, Q3) and, respectively, to the second (Q2, Q4) transistors of said two pairs of transistors.

A unity gain analog signal amplifier for low voltage applications, with no DC level shifting so as to preserve dynamic range, a large bandwidth, a good driving capability for capacitive loads and a rail-to-rail output voltage range. A differential amplifier composed of matched MOSFETs is biased between current source and sink circuits. The current source is a current mirror which provides equal currents through the two branches of the differential amplifier, while the tail current is sunk by the current sink circuit. The analog input signal drives the gate terminal of one of the MOSFETs and the gate and drain terminals of the other MOSFET are connected together and provide the output signal. An additional current mirror branch driven by the current source and connected to the output terminal provides increased output current driving capacity and output voltage pull up. With two such circuits connected in a symmetrical push-pull configuration, output current sourcing and sinking as well as output voltage pull up and pull down capabilities are realized.

An amplifier arrangement comprising a plurality of similar amplifier stages to which input signal voltages are applied in common, the output signal voltages being summed to retain bandwidth at the expense of gain compared with cascaded stages. The individual stages of the arrangement may be cascoded amplifier stages.

A high-current, very-wide-band transconductance amplifier includes a differential voltage to current converter and a plurality of complementary unipolar current mirror cells. The differential voltage to current converter isolates the input voltage terminal from the common side of the output load current terminal. A plurality of positive current mirror cells are connected in parallel and a plurality of negative current mirror cells are connected in parallel to avoid the need for a single low resistance current sensing resistor and the fabrication problems inherent in such resistors.

There is provided a thin film transistor circuit used for a driver circuit for providing a semiconductor display device without a picture blur and with high fineness/high resolution. In the thin film transistor circuit, a TFT having a large size (channel width) is not used, but a plurality of TFTs each having a small size are connected in parallel to each other and are used. By this, while sufficient current capacity of the thin film transistors is secured, fluctuation in the characteristics can be decreased.