Kabushiki Kaisha Toshiba

Junkei Goto

Tetsuya Iida

Hiroshi Takakura

Masayuki Sahoda

The current paths of the P-channel transistor, P-channel transistor, and N-channel transistor are connected in series between the power source V.sub.DD and the ground. The inverter circuit is constituted by the transistors. The node of the inverter circuit is connected to an end of the current path of the N-channel transistor. Another end of the current path of the N-channel transistor is connected to the input node. The transistors are of the enhancement type. If the electric potential higher than the power source V.sub.DD is supplied to the input node, the voltage of the node is lower than that of the power source V.sub.DD by the threshold voltage (V.sub.THN) and the transistors are protected from destruction.

CMOS level conversion circuit with input protection

A segment control type D to A converter includes a decoder and a plurality of current source cells. The decoder decodes a digital input signal to generate a control signal. The plurality of current source cells are selected by the control signal output from the decoder. A current output from the selected current source cell is output from an output terminal. Each of the current source cells includes first and second transistors. One terminal of the current path of the first transistor is connected to a constant current source, and the first transistor is ON/OFF controlled such that the gate of the transistor receives the control signal output from the decoder. One terminal of the current path of the second transistor is connected to the other terminal of the current path of the first transistor, and the other terminal of the second transistor is connected to the output terminal. A reference voltage is applied to the gate of the second transistor to cause the second transistor to be normally set in an ON state.

Current source cell use in current segment type D and A converter

This invention discloses an analog-to-digital converter. Current supply paths are branched at the current supply terminals from the other current paths so as to be connected exclusively to the analog voltage comparator. And a circuit block of the analog voltage comparator is positioned closer to the current supply terminals than the other circuit block of DA converter, sequential comparison register, etc.

Analog-to-digital converter with isolated power supply lines to the

A signal interference prevention wiring is disposed between two wirings which are arranged in parallel for transmitting a signal, and the signal interference prevention wiring is held at a constant potential.

Semiconductor integrated circuit device

A successive approximation type A/D converter of the present invention has a capacitor having a predetermined capacitance value and arranged between an input terminal of a voltage comparator and a fixed potential terminal having a predetermined potential. According to the successive approximation type A/D converter of the present invention, the capacitor arranged between the input terminal of the voltage comparator and the fixed potential terminal having the predetermined potential prevents a potential at the input node of the voltage comparator from being greatly changed to exceed a power source voltage range due the influences of a local D/A converter when the sample mode is switched to the approximation mode. Therefore, the leakage of charges stored in the input side of the voltage comparator can be prevented. Accordingly, even if the amplitude of an analog input voltage is equal to the amplitude of the power source voltage, high-precision A/D conversion can still be performed.

Successive approximation type A/D converter

In the comparator circuit, the amplifier circuit is comprised of an inverting amplifier section having a high gain and a noninverting amplifier section having a low output impedance. Therefore, the comparator circuit has a high input sensitivity. The comparator circuit can also operate at a high speed.

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Kawasaki, Japan

Junkei Goto