摘要:
Data transmitter circuitry on a programmable logic device (“PLD”) includes a plurality of channels of serializer circuitry, and a plurality of clock multiplier units (“CMUs”), each of which is associated with a respective subplurality of the serializer channels. Each CMU includes multiple reference clock signal sources, multiple phase-locked loop (“PLL”) circuits, and circuitry for allowing any PLL to get its reference input from any of the reference sources. Raw and centrally processed clock signals produced by each CMU are distributed to the serializer channels associated with that CMU and, at least in the case of the centrally processed signals, to the serializer channels associated with another CMU. The signal that controls release of parallel data to each serializer channel can be an output signal of that channel, or it can be an output signal of any CMU from which that channel can get a clock signal.
摘要:
Methods and circuits are provided for producing phase-adjusted pre-emphasis and equalization. In applications in which little or no phase distortion occurs during signal transmission, propagation, or reception, linear-phase pre-emphasis or equalization can be used to reduce or eliminate phase distortion introduced by the pre-emphasis or equalization. Linear phase, constant group delay FIR filters or circuits may have odd numbers of coefficients symmetrical about the middle coefficient. In applications in which signal phase distortion occurs, linear phase or non-linear phase pre-emphasis or equalization can be used to reduce or compensate for the phase distortion. Phase compensation may be effected using FIR pre-emphasis and equalization filters and circuits. Non-linear phase FIR filters may have different numbers and combinations of coefficients.
摘要:
A reference clock receiver structure according to the invention is provided. The structure preferably includes an input buffer that is formed from a PMOS differentiated pair of transistors and a first supply voltage. The PMOS differential pair receives a pair of differential inputs, and produces a pair of differential outputs. The structure also includes a level shifter that is coupled to receive the pair of differential outputs from the input buffer to provide gain to the pair of differential outputs to form a gained pair of differential outputs. The level shifter that includes a second supply voltage. The second supply voltage may have a smaller magnitude than the first supply voltage. Finally, the structure includes a CMOS buffer that is coupled to receive the gained pair of differential outputs. The CMOS buffer boosts the gained pair of differential outputs and converts the gained differential pair outputs into a single signal.
摘要:
The various components of transceiver circuitry on an integrated circuit are put together in various ways for purposes of being supplied with power to help prevent noise propagation between the groups. In the case of multi-channel transceiver circuitry there can be various amounts of power supply sharing between similar groups in multiple channels.
摘要:
Charge pump circuitry is provided that is insensitive to charge sharing and current mismatch effects. The charge pump circuitry has an output node at which a charge pump output voltage is provided. A first current source charges the output node to increase the output voltage or a second current source discharge the output node to decrease the output voltage. The charge pump circuitry uses a unit-gain op-amp circuit to prevent charge sharing effects from affecting the output voltage when switching between discharging and charging operations. A low-pass filter is used to reduce feedback noise on the output node. A replica feedback circuit prevents current mismatch between the currents produced by the first and second current sources. The first and second current sources may be formed using programmable transistors that are adjusted by static control signals provided by programmable elements to further minimize current mismatch.
摘要:
Charge pump circuitry is provided that is insensitive to charge sharing and current mismatch effects. The charge pump circuitry has an output node at which a charge pump output voltage is provided. A first current source charges the output node to increase the output voltage or a second current source discharge the output node to decrease the output voltage. The charge pump circuitry uses a unit-gain op-amp circuit to prevent charge sharing effects from affecting the output voltage when switching between discharging and charging operations. A low-pass filter is used to reduce feedback noise on the output node. A replica feedback circuit prevents current mismatch between the currents produced by the first and second current sources. The first and second current sources may be formed using programmable transistors that are adjusted by static control signals provided by programmable elements to further minimize current mismatch.
摘要:
A dual-mode LVDS/CML transmitter allows a single circuit to operate as either an LVDS transmitter or a CML transmitter. The transmitter mode can be switched by activating or deactivating appropriate circuit elements, and changing the voltage or current produced by appropriate sources or sinks. This flexibility allows a single transmitter to operate well in both AC and DC coupling conditions, and facilitates interoperation with a greater variety of receivers.
摘要:
Voltage controlled oscillator (“VCO”) circuitry includes LC tank or ring VCO circuitry and frequency divider circuitry that divides the frequency output by the oscillator circuitry by a selectable integer factor that is at least 2 in the case of a ring oscillator or at least 4 in the case of an LC tank oscillator. This arrangement allows the oscillator circuitry to operate at frequencies that are higher than the desired final output frequencies, which has such advantages as reducing the size and power consumption of the oscillator circuitry, and allowing the circuitry as a whole to have a wide range of operating frequencies while reducing the frequency range over which the oscillator circuitry may be required to operate.
摘要:
Charge pump circuitry is provided that is insensitive to charge sharing and current mismatch effects. The charge pump circuitry has an output node at which a charge pump output voltage is provided. A first current source charges the output node to increase the output voltage or a second current source discharge the output node to decrease the output voltage. The charge pump circuitry uses a unit-gain op-amp circuit to prevent charge sharing effects from affecting the output voltage when switching between discharging and charging operations. A low-pass filter is used to reduce feedback noise on the output node. A replica feedback circuit prevents current mismatch between the currents produced by the first and second current sources. The first and second current sources may be formed using programmable transistors that are adjusted by static control signals provided by programmable elements to further minimize current mismatch.
摘要:
Charge pump circuitry is provided that is insensitive to charge sharing and current mismatch effects. The charge pump circuitry has an output node at which a charge pump output voltage is provided. A first current source charges the output node to increase the output voltage or a second current source discharge the output node to decrease the output voltage. The charge pump circuitry uses a unit-gain op-amp circuit to prevent charge sharing effects from affecting the output voltage when switching between discharging and charging operations. A low-pass filter is used to reduce feedback noise on the output node. A replica feedback circuit prevents current mismatch between the currents produced by the first and second current sources. The first and second current sources may be formed using programmable transistors that are adjusted by static control signals provided by programmable elements to further minimize current mismatch.