Abstract: A structure having substantial surface evenness is created by a method in which an insulating layer (24) that has an upward protrusion (26) is formed on a patterned conductive layer (20) having a corresponding upward protrusion (22). A further layer (28) having a generally planar surface is formed on the insulating layer. Using an etchant that attacks the further layer much more than the insulating layer, the further layer is etched to expose at least part of the insulating protrusion. The further layer and the insulating layer (as it becomes exposed) are then etched with an etchant that attacks both of them at rates not substantially different from each other. This brings the upper surface down without exposing the conductive layer, particularly its upward protrusion.

Abstract: An absolute-value analog-to-digital converter containing a chain of matched main absolute-value differential amplifiers (A.sub.1 -A.sub.N) has a gain control for regulating the gain of each main amplifier utilizing an auxiliary absolute-value differential amplifier (A.sub.GC) matched to the main amplifiers. An offset control in the converter drives the offsets of the amplifiers toward zero by using a further absolute-value differential amplifier (A.sub.OC) matched to the other amplifiers. The gain and offset control are implemented with suitable feedback circuitry.

Abstract: A sample and hold circuit contains a pair of differential amplifiers (A1 and A2) switchably arranged in series. The circiut input signal (V.sub.IN) during sample is provided to the first amplifier (A1) which is coupled to a storage capacitor (C). The second amplifier (A2) provides the circuit output signal (V.sub.OUT) during hold. Switching circuitry (S1, S2, and S3) enables the input and output signals to undergo the same transfer function in the first amplifier. The voltage offset of the first amplifier is thereby cancelled out of the output signal, while the effect of the voltage offset of the second amplifier is reduced drastically so as to provide excellent auto-zeroing.

Abstract: In fabricating a PROM cell, an electrical isolation mechanism (44 and 32) is formed in a semiconductive body to separate islands of an upper zone (36) of first type conductivity (N) in the body. A semiconductor is introduced into one of the islands to produce a region (48) of opposite type conductivity (P) that forms a PN junction with adjacent semiconductive material of the island. Ions are implanted to convert a surface layer (60) of the region into a highly resistive amorphous form which is irreversibly switchable to a low resistance state. A path of first type conductivity extending from the PN junction through another of the islands to its upper surface is created in the body to complete the basic cell.

Abstract: In fabricating a PROM cell, an electrical isolation mechanism (44 and 32) is formed in a semiconductive body to separate islands of an upper zone (36) of first type conductivity (N) in the body. A semiconductor impurity is introduced into one of the islands to produce a region (48) of opposite type conductivity (P) that forms a PN junction laterally bounded by the island's side boundaries. A highly resistive amorphous semiconductive layer (58) which is irreversibly switchable to a low resistive state is deposited above the region in such a manner as to be electrically coupled to the region. A path of first type conductivity extending from the PN junction through another of the islands to its upper surface is created in the body to complete the basic cell.

Abstract: A multi-stage amplifier (21, 22, 23, or 24) has three or more amplifier stages (A1, A2, and A3) arranged in a capacitatively nested configuration for frequency compensation. The technique consists of nesting two of the stages together with a pole-splitting capacitor (C1) to form a stable device (21 or 22) and then nesting this device and a third of the stages together with another pole-splitting capacitor (C2) to form the amplifier.

Abstract: A differential amplifier operable between a pair of supply voltages that define a rail-to-rail supply range contains a pair of differential portions (20 and 22) that together provide representative signal amplification across the supply range, although neither differential portion individually does so. A current control (24) regulates operating currents (I.sub.N and I.sub.p) for the differential portions in such a way that the amplifier transconductance can be controlled in a desired manner as the common-mode part (V.sub.CM) of the amplifier input signal (V.sub.I+ and V.sub.I-) varies across the supply range. The transconductance is typically controlled to be largely constant. A summing circuit (26) selectively combines internal currents (I.sub.A, I.sub.B, I.sub.C, and I.sub.D) from the differential portions to generate at least one output signal (I.sub.O+ and I.sub.O-) representative of the input signal.

Abstract: A layer of a conductive material consisting of aluminum alone or in combination with a small percentage of copper and/or silicon is formed on a semiconductor surface in a two-step deposition process in such a manner as to largely avoid serious continuity defects in the layer.

Abstract: A bipolar voltage translator contains a pair of differentially coupled transistors (Q1 and Q2) for converting an input voltage (V.sub.IN) supplied to one (Q1) of the pair into an output voltage (V.sub.OUT) taken between the other (Q2) and a first resistor (R9). A further transistor (Q4) coupled through a second resistor (R12) to a V.sub.EE supply provides current for the differential pair. A voltage reference circuit (10) containing at least three serially coupled diodes (S5, J3, and J4) with a resistive voltage divider (R13 and R14) across an intermediate one (J3) of the diodes provides the current-source transistor with a reference voltage (V.sub.REF2) that equals V.sub.EE +(1+.alpha.)V.sub.BE where .alpha. is 0.2-3.0. The ratio of the first resistor to the second is desirably .beta./.alpha. where .beta.is the output voltage swing divided by V.sub.BE. If .beta. is 1 and the transistors are NPN devices, the output voltage level is suitable for current tree logic.

Abstract: A MOS power-on reset circuit includes Schmitt trigger circuit and an inverter. The Schmitt trigger circuit comprises first, second, and third depletion transistors serially connected between reference potential and supply voltage. The first and second depletion transistors are connected at a first junction point, and the second and third depletion transistors are connected at a second junction point. The gates of the first and second depletion transistors are commonly connected for receiving an input substrate bias voltage. An enhancement transistor is connected between the first junction point and supply voltage. The gates of the enhancement transistor and the third depletion transistor are commonly connected to the second junction point, which is the output of the Schmitt trigger circuit and which is coupled to the inverter from which the output voltage is taken.

Abstract: A semiconductor circuit supplies a substrate back bias voltage that is feedback controlled as a function of the sum of the positive threshold voltage of one field-effect transistor (FET) and the negative threshold voltage of a second FET. Preferably, one of the FET's is an enhancement-mode device, and the other is a like-polarity depletion-mode device. This arrangement enables the bias voltage to vary from chip to chip in such a manner as to speed up the logic gates on a chip containing the slowest gates and to slow down the logic gates on a chip containing the fastest logic gates, thereby decreasing the chip-to-chip spread in gate propagation delay and average power dissipation. The worst-case noise margin increases slightly.

Abstract: An arbiter circuit includes a latch made of two crosscoupled NAND gates, one of which is a Schmitt NAND gate, a difference detector, and two output NOR gates. The output of the latch is coupled to the difference detector and to one input of the NOR gates. The NOR gates receive another input from the difference detector. The difference detector is responsive to a voltage difference that exceeds one V.sub.BE, thereby blocking signals that originate in the latch during oscillating or metastable states of the latch, which may include rut pulses.