Abstract: A low jitter external clocking system and method are disclosed. According to one embodiment of the present invention, a differential clock signal is received on a first clock signal line and a second clock signal line. A differential amplifier coupled to the first clock signal line and the second clock signal line amplifies the differential clock signal into a single-ended output clock signal.

Abstract: A voltage-to-current circuit utilizes an NMOS-input voltage-to-current (V-I) converter and a PMOS-input V-I converter, with both driving a common gate output stage. Each of the V-I converters includes a transconductance amplifier and a current mirror. The common gate output stage includes two series connected complementary pairs of transistors. One complementary pair drives the output, and the other complementary pair biases the first. The V-I circuit can be utilized as part of a phase detector, which is in turn can be utilized as part of a phase lock loop or a delay lock loop.

Abstract: A differential amplifier is provided, incorporating negative hysteresis by automatic reference voltage adjustment. A delayed output signal is routed to a switch or multiplexer which functions to select one of two reference voltage levels, creating negative hysteresis. The delayed output signal is delayed by a series of inverters, which prevent certain embodiments of the invention from oscillating under some conditions. The two reference voltage levels are selected to be near the respective data signal input high and low signal voltage levels, but far enough from these levels so as not to be adversely affected by noise or other interference.

Abstract: A semiconductor circuit having an analog storage array, a sense amplifier array in which each sense amp cell generates a differential signal pair in response to receiving first and second signals from the storage array. The circuit also includes an analog multiplexer through which a selected differential signal pair is driven into a signal processing pipe. In another embodiment, the sense amp cells each include an operational amplifier (opamp) pair configured as unity-gain closed loop amplifiers for driving the differential signal pair through the analog multiplexer. To improve settling time, the opamps are designed to provide an underdamped response while loaded with the analog transmission path through the analog mux. In yet another embodiment, each sense amp cell is activated one clock cycle before it is read. This allows speedy readout while transitioning from one cell to the next.

Abstract: A differential delay cell includes load transistors and a current source transistor biased linearly. The delay control input of the differential delay cell is also the power supply input such that when the power supply voltage changes, the delay in the differential delay cell changes. The resistance presented by the load transistors changes as a function of the power supply voltage, as does the current sourced by the variable current source. The combination of changing resistance and changing current as the power supply voltage changes results in a substantially constant output voltage swing. A ring of differential delay cells is included in a voltage controlled oscillator, which is in turn included in a phase lock loop. The phase lock loop has a wide loop bandwidth and the voltage controlled oscillator has a good power supply rejection ratio.

Abstract: An adaptive body bias circuit forward or reverse biases bodies of transistors within a compensated circuit as a result of measured parameters of an integrated circuit. The adaptive body bias circuit includes a matched circuit that includes a replica of a signal path within the compensated circuit. The phase of a clock signal at the input to the matched circuit is compared to a phase of a delayed clock signal at the output of the matched circuit. When the delay through the matched circuit varies about one period of the clock signal, a non-zero error value is produced. A bias voltage is generated as a function of the error value, and the bias voltage is applied to the compensated circuit as well as the matched circuit. Integrated circuits can include many adaptive body bias circuits. Bias values can be stored in memories for later use, and bias values within memories can be updated periodically to compensate the circuit over time.

Abstract: A complementary input self-biased differential amplifier includes gain compensation devices. The gain compensation devices are in parallel with input transistors and are biased by a self-bias node. The gain control devices serve to keep current flowing in load devices when operating at common-mode extremes, thereby limiting the reduction in amplifier output impedance and limiting the corresponding reduction in differential-mode gain at common-mode extremes. The gain control devices also serve to reduce input stage transconductance near the center of the common-mode input voltage swing, thereby reducing differential-mode gain near the center of the swing, and reducing gain variations across the input common-mode range. The differential amplifier can include multiple input legs on either side of an input stage. Multiple legs allow multiple reference voltages to be compared to a data signal.

Abstract: A frequency divider includes a pulse generator, a latch with differential outputs, and switches responsive to the state of the latch. The latch changes logical state in response to signal pulses produced by the pulse generator. The signal pulses are produced by the pulse generator in response to rising edges of an input signal applied to the pulse generator. A first output alignment circuit provides additional drive strength to a first of the differential outputs when it is transitioning high. A second output alignment circuit provides additional drive strength to a second of the differential outputs when it is transitioning high.

Abstract: A differential signal generator accepts a single-ended signal on an input node and produces a differential signal on differential output nodes. The differential output nodes include a true output node and a complementary output node. In one embodiment, the differential signal generator includes a memory element coupled between the differential output nodes, a first switch that conditionally couples one of the differential output nodes to a reference node, and a second switch that conditionally couples the other differential output node to the same reference node. The memory element includes a latch having cross-coupled inverters. The cross-coupled inverters are each skewed to respond more quickly to one edge of an input signal. When the switches conditionally couple one of the differential output nodes to a ground node, the inverters are skewed to respond more quickly to falling edge input signals.