摘要:
One embodiment relates to an integrated circuit which includes multiple communication channels, a clock multiplexer in each channel, two low-jitter clock generator circuits, and clock distribution circuitry. Each channel includes circuitry arranged to communicate a serial data stream using a reference clock signal, and the clock multiplexer in each channel is configured to select the reference clock signal from a plurality of input clock signals. The first low-jitter clock generator circuit is arranged to generate a first clock signal using a first inductor-capacitor-based oscillator circuit, and the second low-jitter clock generator circuit is arranged to generate a second clock signal using a second inductor-capacitor-based oscillator circuit The first and second inductor-capacitor-based oscillator circuits have different tuning ranges. The clock distribution circuitry is arranged to input the first and second low-jitter clock signals to each said clock multiplexer. Other embodiments and features are also disclosed.
摘要:
An integrated circuit capable of monitoring analog voltages inside an analog block is presented. The integrated circuit has an analog test multiplexer (mux) whose inputs are connected to analog voltages of interest inside an analog block. The analog test multiplexer directs a selected analog voltage from an analog block to the output of the analog test mux. The integrated circuit further includes an analog monitor state machine which provides the selection bits to the analog test multiplexer, enabling random access to the analog voltages inside the analog block. The integrated circuit also includes an analog to digital converter for converting the selected analog voltage from the analog test multiplexer into a digital representation.
摘要:
An integrated circuit (e.g., a programmable integrated circuit such as a programmable microcontroller, a programmable logic device, etc.) includes programmable circuitry and 10 Gigabit Ethernet (10 GbE) transceiver circuitry. The programmable circuitry and the transceiver circuitry may be configured to implement the physical (PHY) layer of the 10 GbE networking specification. This integrated circuit may then be coupled to an optical transceiver module in order to transmit and receive 10 GbE optical signals. The transceiver circuitry and interface circuitry that connects the transceiver circuitry with the programmable circuitry may be hard-wired or partially hard-wired.
摘要:
An oscillator circuit includes transistors that are cross-coupled through routing conductors in a first conductive layer. The oscillator circuit also includes a varactor, a capacitor, and an option conductor in a second conductive layer. The option conductor forms at least a portion of a connection between one of the transistors and the capacitor or the varactor.
摘要:
Signal detection circuitry for a serial interface oversamples the input—i.e., samples the input multiple times per clock cycle—so that the likelihood of missing a signal is reduced. Sampling may be done with a regenerative latch which has a large bandwidth and can latch a signal at high speed. The amplitude threshold for detection may be programmable, particularly in a programmable device. Thus, between the use of a regenerative latch which is likely to catch any signal that might be present, and the use of oversampling to avoid the problem of sampling at the wrong time, the likelihood of failing to detect a signal is greatly diminished. Logic, such as a state machine, may be used to determine whether the samples captured s do or do not represent a signal. That logic may be programmable, allowing a user to set various parameters for signal detection.
摘要:
An integrated circuit (e.g., a programmable integrated circuit such as a programmable microcontroller, a programmable logic device, etc.) includes high-speed serial data signal interface channels, some of which include more circuitry that is dedicated to performing various high-speed serial interface functions than others of those channels have. To increase the flexibility with which such circuitry in a more feature-rich channel can be used, routing is provided for selectively allowing a less feature-rich channel to use certain dedicated circuitry of a more feature-rich channel that is not itself using all of its dedicated circuitry.
摘要:
Transmitter driver circuitry for outputting a high-speed serial data signal (e.g., in the range of about 10 gigabits per second or higher) includes H-tree driver circuitry having only a main driver stage and a post-tap driver stage. At least one transistor in the H-tree driver circuitry is constructed and connected to provide electrostatic discharge protection. PMOS and NMOS current sources are used for the H-tree driver circuitry to enhance power supply noise rejection.
摘要:
A pre-emphasis circuitry that includes (1) a pre-emphasis voltage variation compensation (PVVC) engine having a transition detection circuit and (2) a compensation driver coupled to the PVVC engine is described. In one embodiment, the compensation driver reduces data dependent voltage variations in pre-emphasis provided by the pre-emphasis circuitry. In one embodiment, in response to a predetermined data pattern detected by the PVVC engine, the compensation driver provides an additional boost to performance critical capacitive nodes of the pre-emphasis circuitry. The additional boost causes the performance critical capacitive nodes to charge or discharge more rapidly. In one embodiment, the PVVC engine further includes a digital finite impulse response (FIR) filter coupled to the transition detection circuit. Also, in one embodiment, the PVVC engine further includes an FIR delay circuit coupled to the digital FIR filter and a synchronizer circuit coupled to the digital FIR filter and the FIR delay circuit, where the FIR delay circuit introduces latency to match-delay produced by the transition detection circuit and the synchronizer circuit synchronizes data to be sent to the main driver, the pre-emphasis driver, and the compensation driver.
摘要:
Automatic rate negotiation logic for a high speed serial interface in a programmable logic device determines whether multiple occurrences of a single-bit transition (i.e., a data transition from “0” to “1” to “0” or from “1” to “0” to “1”) occur within a predetermined time interval on a data channel of a high-speed serial interface. The interval preferably is selected such that multiple occurrences of a single-bit transition mean that the data channel is operating in full-rate mode. The rate negotiation logic may share a phase detector with clock data recovery circuitry in the interface. The phase detector may be a bang-bang phase detector specially adapted to detect single-bit transitions.
摘要:
Integrated circuits with decoupling capacitor circuitry are provided. Decoupling capacitor circuitry may include multiple arrays of decoupling capacitors. Each decoupling capacitor array may have a corresponding decoupling capacitor monitoring circuit that is associated with that decoupling capacitor array. Each decoupling capacitor monitoring circuit may include a resistor and switching circuitry. Each decoupling capacitor monitoring circuit may be coupled to a comparator and control circuitry. During testing, the control circuitry may configure each decoupling capacitor array for leakage current testing one at a time. If a decoupling capacitor array is determined to exhibit excessive leakage currents, that decoupling capacitor array will be marked as defective and will be disabled from use. If the decoupling capacitor array is determined to exhibit tolerable leakage currents, that decoupling capacitor array will be enable for use to help reduce power supply noise.