Abstract: A constantly conductive MOS transistor is placed in a logic circuit including a plurality of switching MOS transistors. The switching MOS transistors and the constantly conductive MOS transistor are connected in series and each receive a control signal at their respective gates. The constantly conductive transistor is in a conductive state regardless of the state of its control signal. Thus, it is difficult for a third party to learn the true logic structure of the logic circuit by visual inspection, as the third party will tend to recognize the constantly conductive transistor as a true transistor contributing to the logic circuit, and not as a constantly conductive "dummy" transistor.

Abstract: A programmable buffer circuit includes a first stage circuit which receives an input signal IN indicative of a first or second value, and a second stage circuit, responsive to an output of the first stage circuit, for outputting one of a value designated depending on the value of the input signal and a value designated regardless of the value of the input signal. The second stage circuit includes a plurality of MOS transistors whose conduction properties change depending on whether ion implantation is applied thereto. By applying the ion implantation selectively to the MOS transistors, the second stage circuit is operated as a transfer logical function circuit or an inverter logical function circuit.

Abstract: A semiconductor circuit includes an input, an output, and a first transistor and a second transistor coupled in series to a power source. The first transistor is coupled closer to the power source than the second transistor is, and the first transistor has a higher threshold voltage than a threshold voltage of the second transistor. The semiconductor circuit further includes a capacitor which in coupled between the first transistor and the second transistor.

Abstract: Depletion mode pass gates utilized in a PLD to enable a gate voltage of Vcc to be applied for turn off, as opposed to a higher voltage required for enhancement type devices. With Vcc applied for turn off, gate oxide stress is reduced and chip reliability increased. A decoder utilizing PMOS transistors is further used to supply a negative gate voltage to enable turn off of the depletion mode pass gates. In one embodiment, to prevent pumping the power supply voltage above Vcc when supplying Vcc to gates of the pass gates, the decoder is an all PMOS device using PMOS transistors to connect Vcc to gates of the pass gates. In another embodiment both NMOS and PMOS transistors are utilized, with PMOS blocking transistors utilized to prevent a negative voltage from being applied to the NMOS transistors and causing current leakage. A negative voltage pump is further provided to supply a sufficient negative voltage.

Abstract: A CMOS inverter capable of reducing a through current therein including an E-type PMOS transistor, an E-type NMOS transistor and a D-type NMOS transistor. In the E-type PMOS transistor, the gate and the drain are connected to input and output terminals. In the E-type NMOS transistor, the gate and the drain are connected to the input and the output terminals and the source to the ground. In the D-type NMOS transistor, the source is connected to the source of the E-type PMOS transistor, the gate to the ground, and the drain to a power source.

Abstract: A high-speed solid state buffer circuit and method for producing the same. A buffer circuit accepts logic input signals and transforms the signals to an output signal which can drive a heavy load. By using an output stage pull-up device that includes a parallel combination of an enhancement mode FET and a depletion mode FET, a solid-state buffer circuit with increased speed and output voltage swing is achieved. Most conveniently, the buffer takes the form of a logic inverter. However, the buffer can also be used to form a multiple input NOR gate. The circuit is most suitable for realization in GaAs technology.

Abstract: A logic gate circuit includes a resistor, a current limiting circuit, a switching transistor, and a load transistor, the source of load transistor being connected to the drain of the switching transistor, the gate of the switching transistor being connected to an input terminal, the resistor being connected between the source of and the gate of the load transistor, and the current limiting circuit being connected between the gate of the load transistor and the source of the switching transistor. By using this logic gate circuit in the low speed operating section of an LSI, the dissipation current and the chip area of the LSI can be reduced even when the gate width and the threshold voltage of the load FET are the same as those in the high speed operating section.

Abstract: A tri-state CMOS output buffer is provided which exhibits a relatively low input capacitance and tolerance to a range of operating voltages. The output buffer includes a PUP input, a PD input and an output. The output buffer includes a source follower circuit coupled to the PUP input such that the output of the source follower generally follows transitions in the PUP input signal. The source follower output is the buffer output. A pull-down transistor is coupled between the buffer output and ground to pull-down the output voltage when the PD signal goes high. A pull-up transistor and an isolation transistor are coupled in series to form a series coupled circuit. This series-coupled circuit is coupled in parallel with the source follower. The pull-up transistor pulls up the voltage on the buffer output when the PUP input signal goes high. The isolation transistor is switchable to an off state to isolate a parasitic diode associated with the pull-up transistor.