Abstract: A differential input buffer that can operate at lower power supply voltages and can receive differential input signals with wide common mode rage. In various embodiments, the invention combines native or depletion mode metal-oxide-semiconductor (MOS) transistors with the conventional enhancement mode n-channel (NMOS) and p-channel (PMOS) transistors in the design of the input buffer. The native or depletion MOS transistors can operate at lower power supply voltages and increase the input common-mode voltage range.

Abstract: A programmable logic device includes configurable phase-locked loop (PLL) circuitry that outputs multiple clock signals having programmable phases and frequencies. Each output signal is programmably selectable for use as an external clock, internal global clock, internal local clock, or combinations thereof. The PLL circuitry has programmable frequency dividing, including programmable cascaded frequency dividing, and programmable output signal multiplexing that provide a high degree of clock design flexibility.

Abstract: A programmable logic device includes configurable phase-locked loop (PLL) circuitry that outputs multiple clock signals having programmable phases and frequencies. Each output signal is programmably selectable for use as an external clock, internal global clock, internal local clock, or combinations thereof. The PLL circuitry has programmable frequency dividing, including programmable cascaded frequency dividing, and programmable output signal multiplexing that provide a high degree of clock design flexibility.

Abstract: Charge pump circuits and methods of the present invention step up an input voltage to provide an output voltage. The charge pump circuits have one or more stages. Each stage may include a capacitor and a transistor. Each stage adds an incremental voltage to an input voltage. The capacitors elevate the voltage at a terminal of the transistors in each stage in response to a clock signal to provide the incremental voltage. The output voltage is the sum of the input voltage and the incremental voltages provided by each stage. One or more of the stages of the charge pump circuit may have a depletion transistor. Depletion transistors may be field-effect transistors that have a lower threshold voltage as a result of an implant in the channel region of the device.