A high speed interstage STL buffer (27) is disclosed having a low threshold and high driving capability. A first Schottky-clamped grounded emitter transistor (28) receives input signals through a Schottky steering diode (38) and inverts the input signal. The input signal is applied in parallel through a Schottky steering diode (20) to a second Schottky-clamped grounded emitter transistor (12). The collector (22) of the second transistor (12) provides an output of the buffer (27) for driving load current in one direction with respect to the buffer output. A third transistor (40) connected as an emitter follower has the emitter (42) thereof connected to the buffer output for driving load currents in the other direction. The base (46) of the emitter follower transistor (40) is coupled by a Schottky steering diode (50) to the collector (32) of the first transistor (28). The steering diodes (20, 38, 50) have a forward threshold voltage less than that of the Schottky-barrier diodes used to clamp the base-collector junctions of the first and second transistors (28, 12).
This application is a continuation of application Ser. No. 185,232 filed Apr. 18, 1988, now abandoned, which is a continuation of Ser. No. 851,055, filed Apr. 11, 1986, now abandoned.
A self-powered intelligent computer accessory device has a serial data input port and a parallel data output port and is used for interconnection from computer to computer and between a computer and a peripheral device. The accessory device uses a full wave diode bridge to generate bipolar supply voltages referenced to ground from the serial data port to power a microprocessor of the accessory device. A power extraction circuit is provided on the output side of the microprocessor for extracting power from standard pull-up resistors within the peripheral device to power an output buffer circuit. The period of time in which power is extracted from the pullup resistors is maximized by using an enable control signal from the microprocessor to ensure that the output buffer circuit is only driving the external peripheral device during the output data strobe sequence and at all other times is not consuming power. The buffer circuit is constructed and controlled such that it is capable of driving the load of the external peripheral device but draws virtually no power in performing this task.
An ECL/CML to TTL translator circuit couples the output of an ECL/CML gate to the input of a TTL gate. The ECL/CML gate operates with reference to a first power rail higher reference voltage level with transistor elements operating in the non-saturation operating region. The TTL gate operates with reference to a second power rail lower reference voltage level with transistor elements operating in the saturation threshold operating region. The translator circuit includes a reference voltage level shifting constant current non-switching current mirror circuit coupled to the output of the ECL/CML gate for shifting the reference voltage level of the ECL/CML gate output from the higher reference voltage level to the lower reference voltage level. An operating region translating emitter follower output buffer circuit is coupled to receive the voltage level shifted output signal and drive the input of the TTL gate. The circuit functions of reference voltage level shifting and of operating region translating are thereby separated. Base drive to the phase splitter transistor element is limited by a base drive limiting anti-saturation clamp circuit. More generally, an overdrive and anti-saturation clamp control circuit provides high speed switching of a phase splitter transistor element, pulldown transistor element, or other TTL switching transistor element for generalized application in TTL internal and output gates and buffers. The overdrive and clamp control circuit provides a "programmable" base-collector clamp voltage for operation of TTL switching transistor elements in "soft" saturation, in threshold saturation, or entirely out of saturation for operation of linear TTL circuits.
The disclosure pertains chiefly to an interface including an electrical supply. The disclosure concerns an interface capable of providing an external supply from the amplification of one of the signals. For example, the amplified DTR is used to give a supply voltage to a MIDI interface from an RS 232 serial interface using a nine-pin SUB D9M connector. The disclosure can be applied to the making of interfaces capable of giving an electrical supply to an external device as well as to computers including such interfaces. The disclosure can be applied chiefly to the making of computers capable of working under the MS-DOS operating system and capable of providing a supply voltage to the MIDI interface by means of an RS 232 serial interface and a SUB D9M connector.
An improved method for fabricating polysilicon Schottky clamped transistors and vertical fuse devices in the same semiconductor structure is disclosed. The resulting structure yields an improved Schottky clamped transistor and vertical fuse device. The improved Schottky transistor has a silicide rectifying contact between the base and collector of the transistor, the vertical fuse is provided with a direct contact between an aluminum contact metal and a polysilicon emitter contact.
An improved method for fabricating polysilicon Schottky clamped transistors and vertical fuse devices in the same semiconductor structure is disclosed. The resulting structure yields an improved Schottky clamped transistor and vertical fuse device. The improved Schottky transistor has a silicide rectifying contact between the base and collector of the transistor, the vertical fuse is provided with a direct contact between an aluminum contact metal and a polysilicon emitter contact.
