摘要:
An input buffer circuit has a plurality of selectively enabled differential amplifier circuits, where each differential amplifier is configured for compatibility with a particular differential I/O standard and its corresponding input operating range. For example, the input buffer may have two differential amplifiers suitable for receiving LVDS differential input signals over a wide input operating range, and another differential amplifier suitable for receiving the PCML differential input signals. One or more control signals are provided to the input buffer, e.g., programmably, to selectively enable the required differential amplifier(s) for a given I/O standard.
摘要:
Methods and apparatus for decoding addresses in a memory to provide mixed input and output data widths. A method includes receiving an address portion comprising a first number of bits. A second number of bits of the address portion are blocked, where the second number is less than the first number. A third number of bits are not blocked, and the third number plus the second number equal the first number. The third number of bits are decoded and a fourth number of memory cells are selected. The fourth number is equal to two to the power of the second number. A fourth number of data bits are received and multiplexed to the selected memory cells. The data bits are written to the selected memory cells.
摘要:
A programmable logic device is equipped for various differential signaling schemes by providing a differential output buffer on the device that can be configured according to the needs of the particular differential signaling schemes that may be used. The buffer includes a differential output driver, an adjustable current limiting circuit between the supply voltage and the differential output driver, and an adjustable current limiting circuit between the differential output driver and ground. By selectively adjusting the two current limiting circuits, the output impedance and current, as well as the common mode output voltage and the differential output voltage can be controlled.
摘要:
A programmable integrated circuit may have a memory controller that interfaces between master modules and system memory. The memory controller may receive memory access requests from the masters via ports that have associated priority values and fulfill the memory access requests by configuring system memory to respond to the memory access requests. To dynamically modify the associated priority values while the memory controller receives and fulfills the memory access requests, a priority value update module may be provided that dynamically updates priority values for the memory controller ports. The priority value update module may provide the updated priority values with update registers that are updated based on an update signal and a system clock. The priority values may be provided by shift registers, memory mapped registers, or provided by masters along with each memory access request.
摘要:
An IC that includes a first memory controller, a second memory controller, and a first bonding circuit coupled to the first memory controller, where the first bonding circuit is a hard logic bonding circuit and is operable to coordinate memory control functions of the first memory controller and the second memory controller. In one implementation, the first memory controller is an N bits wide memory controller, the second memory controller is an M bits wide memory controller, and the first bonding circuit is operable to coordinate the memory control functions of the first memory controller and the second memory controller such that the first and second memory controllers together function as an N+M bits wide memory controller, where N and M are positive integers.
摘要:
An integrated circuit may include a memory controller serving as an interface between master processing modules and system memory. The master processing modules may provide memory access requests to the memory controller along with respective tag identifications. The memory controller may place the memory access requests in a queue for fulfillment. The memory controller may include a merging module that generates a memory access request to replace two or more memory access requests previously received from the master processing modules. The merging module may store information associated with the memory access requests that were merged and use the stored information to assign appropriate tag identifications to portions of data obtained from system memory when fulfilling the generated memory access request. The memory controller may include a verification module that can be used with test equipment to optimize the design of the master processing modules for improved memory access performance.
摘要:
Improved decoupling capacitor designs and layout schemes are provided that generate high effective capacitance and high area efficiency at higher frequencies than that of previously known decoupling capacitor designs. The improved decoupling capacitor designs utilize transistor gates with shorter channel lengths to reduce the total parasitic resistance of the channel, thereby providing higher effective capacitance at higher frequencies. To enable higher area efficiency of this decoupling capacitor design, excess contacts are replaced with polysilicon in a grid or waffle pattern.
摘要:
Methods and apparatus for providing either high-speed, or lower-speed, flexible inputs and outputs. An input and output structure having a high-speed input, a high-speed output, a low or moderate speed input, and an low or moderate speed output is provided. One of the input and output circuits are selected and the others are deselected. The high-speed input and output circuits are comparatively simple, in one example having only a clear signal for a control line input, and are able to interface to lower speed circuitry inside the core of an integrated circuit. The low or moderate speed input and output circuits are more flexible, for example, having preset, enable, and clear as control line inputs, and are able to support JTAG boundary testing. These parallel high and lower speed circuits are user selectable such that the input output structure is optimized between speed and functionality depending on the requirements of the application.
摘要:
Methods and apparatus for providing either high-speed, or lower-speed, flexible inputs and outputs. An input and output structure having a high-speed input, a high-speed output, a low or moderate speed input, and an low or moderate speed output is provided. One of the input and output circuits are selected and the others are deselected. The high-speed input and output circuits are comparatively simple, in one example having only a clear signal for a control line input, and are able to interface to lower speed circuitry inside the core of an integrated circuit. The low or moderate speed input and output circuits are more flexible, for example, having preset, enable, and clear as control line inputs, and are able to support JTAG boundary testing. These parallel high and lower speed circuits are user selectable such that the input output structure is optimized between speed and functionality depending on the requirements of the application.
摘要:
A programmable variable depth and width random-access memory circuit is provided. The memory circuit contains rows and columns of memory cells for storing data. A row decoder is used to address individual rows of the memory cells. Column address circuitry receives a column address signal and a width and depth selection signal. A column decoder within the column address circuitry addresses one or more columns of memory cells of the RAM array based on the selected width of the array. The output of the column decoder is routed to the appropriate column or columns of memory cells by a pattern of fixed connections and a group of programmable multiplexers. The number of data output lines to which data signals are provided is determined by the selected width of the RAM array. The output circuitry contains a group of programmable demultiplexers and a routing array having a pattern of fixed connections suitable for passing data signals from the RAM array to the selected number of data output lines.