Abstract: Circuits and methods for loopback testing are provided. A die incorporates a receiver (RX) to each transmitter (TX) as well as a TX to each RX. This architecture is applied to each bit so, e.g., a die that transmits or receives 32 data bits during operation would have 32 transceivers (one for each bit). Focusing on one of the transceivers, a loopback architecture includes a TX data path and an RX data path that are coupled to each other through an external contact, such as a via at the transceiver. The die further includes a transmit clock tree feeding the TX data path and a receive clock tree feeding the RX data path. The transmit clock tree feeds the receive clock tree through a conductive clock node that is exposed on a surface of the die. Some systems further include a variable delay in the clock path.

Abstract: Circuits and methods for Data Bus Inversion (DBI) are provided. In one example, the immediately previous value of the DBI bit affects the next value of the DBI bit. Specifically, in some instances, the value of the DBI bit is held to the immediately previous value of the DBI bit to limit the total number of transitions on a data bus.

Abstract: A circuit includes a first die having a first array of exposed data nodes, and a second die having a second array of exposed data nodes, wherein a given data node of the first array corresponds to a respective data node on the second array, further wherein the first array and the second array share a spatial arrangement of the data nodes, wherein the first die has data inputs and sequential logic circuits for each of the data nodes of the first array on a first side of the first array, and wherein the second die has data outputs and sequential logic circuits for each of the data nodes of the second array on a second side of the second array, the first and second sides being different.

Abstract: Circuits for die-to-die clock distribution are provided. A system includes a transmit clock tree on a first die and a receive clock tree on a second die. The transmit clock tree and the receive clock tree are the same, or very nearly the same, so that the insertion delay for a given bit on the transmit clock tree is the same as an insertion delay for a bit corresponding to the given bit on the receive clock tree. While there may be clock skew from bit-to-bit within the same clock tree, corresponding bits on the different die experience the same clock insertion delays.

Abstract: Circuits and methods for Data Bus Inversion (DBI) are provided. In one example, the immediately previous value of the DBI bit affects the next value of the DBI bit. Specifically, in some instances, the value of the DBI bit is held to the immediately previous value of the DBI bit to limit the total number of transitions on a data bus.

Abstract: An embodiment of a high-density, stacked, planar metal-insulator-metal (MIM) capacitor structure includes a stack of planar electrodes and interposing dielectric layers. Vertically-alternating electrodes are horizontally-staggered, and vias are formed through the multiple electrodes, so that electrical connection is made circumferentially through the via sidewalls to multiple electrodes through which a given via passes. An MIM capacitor incorporating a multiple-level capacitor stack may be fabricated by repeated usage of the same mask operation for each incremental capacitor stack level, and without requiring additional masks beyond those utilized for the first such level.

Abstract: A semiconductor device is presented here. The semiconductor device includes an integrated inductor formed on a semiconductor substrate, a transistor arrangement formed on the semiconductor substrate to modulate loop current induced by the integrated inductor, dielectric material to insulate the integrated inductor from the transistor arrangement, and a controller coupled to the transistor arrangement. The controller is used to select conductive and nonconductive operating states of the transistor arrangement. A conductive operating state of the transistor arrangement allows formation of induced loop current in the transistor arrangement, and a nonconductive operating state of the transistor arrangement inhibits formation of induced loop current in the transistor arrangement.

Abstract: A semiconductor device is presented here. The semiconductor device includes an integrated inductor formed on a semiconductor substrate, a transistor arrangement formed on the semiconductor substrate to modulate loop current induced by the integrated inductor, dielectric material to insulate the integrated inductor from the transistor arrangement, and a controller coupled to the transistor arrangement. The controller is used to select conductive and nonconductive operating states of the transistor arrangement. A conductive operating state of the transistor arrangement allows formation of induced loop current in the transistor arrangement, and a nonconductive operating state of the transistor arrangement inhibits formation of induced loop current in the transistor arrangement.

Abstract: According to one embodiment, a voltage reference circuit operable with a low voltage supply comprises an op-amp powered by the low voltage supply and a feedback branch including a transistor driven by an output of the op-amp. The feedback branch couples the low voltage supply to ground through the transistor and at least a rectifying device situated between a reference node of the feedback branch and ground. An input of the op-amp is coupled to the reference node by a voltage divider. In one embodiment, the voltage reference circuit further comprises a reference branch coupling a second reference node to ground through at least a second rectifying device, and wherein a second input of the op-amp is coupled to the second reference node by a second voltage divider.

Abstract: A pseudo bandgap voltage reference circuit includes a first transistor and a second transistor, each coupled to a supply voltage node. The circuit also includes an amplifier circuit coupled to a gate terminal of each of the first and the second transistors, a current source coupled to the supply voltage node, and a first diode coupled between the current source and a ground reference node. A first input of the amplifier circuit is coupled to a node between the current source and the first diode. In addition, a first terminal of the first transistor is coupled to a second input of the amplifier circuit in a feedback loop. Also, an output reference voltage is developed at an output node coupled to a second terminal of the second transistor. Further, an output current of the current source is independent of a current flowing through the first terminal of the first transistor.

Abstract: A method and apparatus is presented for generating a reference voltage that biases a metal-oxide-semiconductor (MOS) transistor used as a varactor in capacitive tuning applications. In one embodiment, a biasing circuit is implemented. The biasing circuit comprises a diode-clamped FET and an element coupled to the diode-clamped FET at a connection point. The element produces a constant current through the diode-clamped FET. A voltage is produced at the connection point. The voltage is one gate overdrive plus a threshold voltage above ground or one gate overdrive plus a threshold voltage below VDD. Establishing a threshold voltage in this way enables the biasing circuit to track an ideal voltage of a varactor that is coupled to the biasing circuit through the threshold voltage.

Abstract: A method for integrating salicide and self-aligned contact processes in the fabrication of logic circuits with embedded memory is described. Isolation areas are formed on a semiconductor substrate surrounding and electrically isolating device areas. Gate electrodes and associated source and drain regions are formed on and in the semiconductor substrate wherein the gate electrodes have silicon nitride sidewall spacers. A metal silicide layer is formed on the top surface of the gate electrodes and on the top surface of the semiconductor substrate overlying the source and drain regions associated with the gate electrodes using a salicide process. A poly-cap layer is deposited overlying the substrate. The poly-cap layer is selectively removed overlying one of the salicided source and drain regions where a self-aligned contact is to be formed, and overlying another of the salicided source and drain regions and a portion of its associated salicided gate electrode where a butted contact is to be formed.

Abstract: A method of fabricating local interconnects of polycide has been achieved. A substrate is provided. Narrowly spaced features, such as MOS transistor gates and polysilicon traces, are provided overlying the substrate. A dielectric layer is deposited overlying the substrate and the narrowly spaced features. The dielectric layer is patterned to form openings between the narrowly spaced features for planned contacts to the surface of the substrate. A doped polysilicon layer is deposited overlying the dielectric layer and filling the openings. The doped polysilicon layer is etched down to the top surface of the narrowly spaced features. The doped polysilicon layer remains in the spaces between the narrowly spaced features. A polycide layer is formed overlying the narrowly spaced features and the doped polysilicon layer. The polycide layer and the doped polysilicon layer are patterned to complete the contacts and create the local interconnects of polycide, and the integrated circuit device is completed.