摘要:
An apparatus for suppressing the effect of noise from a first circuit on the performance of a second circuit wherein the first and second circuits are on a common substrate. Each of the first and second circuits include first and second supply rails. The apparatus includes a noise isolation circuit and a noise transference circuit. The noise isolation circuit is for coupling the first supply rails of the first and second circuits to prevent noise on the first supply rail of the first circuit from transferring to the first supply rail of the second circuit. The noise transference circuit is for coupling the second supply rails of the first and second circuits so that noise on the second supply rail of the first circuit is transferred to the second supply rail of the second circuit.
摘要:
An apparatus adjusts the duty cycle of a single-ended clock signal. The single-ended clock signal oscillates between first and second voltages. The apparatus includes an error indication circuit, a duty cycle error measurement circuit and a duty cycle adjuster. The error indication circuit includes a reference circuit and a comparison circuit. The reference circuit is coupled to a first node having the first voltage and a second node having the second voltage to generate a reference signal from the first and second voltages. The reference circuit includes at least one instance of a first electrical characteristic cell. The comparison circuit is coupled to receive a feedback clock signal and to generate a comparison signal therefrom. The comparison circuit includes at least one instance of the first electrical characteristic cell. The duty cycle error measurement circuit is coupled to receive the reference signal and the comparison signal. The duty cycle error measurement circuit rejects the common mode of the reference and comparison signals and passes the differential mode of the reference and comparison signals to generate a duty cycle adjust signal responsive to receiving the reference and comparison signals. The duty cycle adjuster is coupled to receive an input clock signal and the duty cycle adjust signal and to provide the single-ended clock signal. The single-ended clock signal has a duty cycle determined at least in part by the duty cycle adjust signal.
摘要:
A microprocessor includes an on-chip low phase noise CMOS LC capacitance oscillator. The LC oscillator is relatively insensitive to power supply fluctuations. In addition, the LC oscillator is operable over a range of frequencies sufficient to support both normal full power operation, and reduced power operation of the microprocessor. The LC oscillator minimizes clock jitter problems and so permits extension of the microprocessor operating frequency to even higher levels than heretofore were possible. An output signal from a phase-frequency detector is a frequency control signal on a frequency control input line of a level converter and filter circuit of the LC oscillator. The output signal from level converter and filter circuit is a filtered frequency control signal on a control voltage input line to a continuously modifiable gigahertz frequency voltage controlled oscillator (VCO) circuit. Continuously modifiable gigahertz frequency VCO circuit generates an output signal with a frequency that is dependent on the voltage on control voltage input line. The output signal from the continuously modifiable gigahertz frequency VCO is a differential current signal to a level shifter output circuit. The level shifter output circuit converts the current signal to a single-ended voltage that is supplied to an output driver. The output driver provides the output signal to a clock distribution network.
摘要:
A clamping circuit which is connected to each long line, preferably adjacent the receiver. The clamping circuit biases the long line at the trigger threshold of the receiver. Thus, instead of amplifying the signal as a repeater will do, the present invention clamps the line to the threshold, thus allowing a faster response since the line doesn't have to be charged or discharged from a lower or higher level to the threshold. This thus speeds up the transition at the receiver without requiring a repeater or a keeper.
摘要:
An improved loop filter contains an active device which maintains a phase lock loop's zero frequency to bandwidth ratio substantially constant with changes in the incoming frequency. It does this by maintaining filter resistance proportional to the inverse square root of the filter current, and without requiring duplicates of circuit elements. Constructed in this way a phase lock loop can be achieved which has a wide operating frequency range and low tracking jitter.
摘要:
In a sample-and-hold circuit, an input is tracked at an output during a tracking period and the input is held during an holding period, the tracking period and holding period defined by a clock signal input to the sample-and-hold circuit, wherein the output is a differential output having a positive output node and a negative output node with the output signal represented by a voltage difference from the negative output node to the positive output node. During the tracking period, an equalizing transistor between the output nodes is turned on to bring the output to a common mode level for the output. During the holding period, the equalizing transistor is turned off and a regenerative circuit drives the output nodes apart, thus amplifying the input signal.
摘要:
A delay-locked loop includes a phase detection circuit, a charge pump circuit and a phase shift circuit. The phase detection circuit is coupled to receive a first signal and a second signal. The phase detection circuit generates a phase-error output signal indicative of whether the first signal is ahead of or behind the second signal in phase responsive to receiving the first and second signals. The charge pump circuit is coupled to receive a phase-error signal derived from the phase-error output signal. The charge pump circuit generates a plurality of control output signals. Each of the control output signals are based upon the phase-error signal and by at least one signal derived from one other of the control output signals. The phase shift circuit is coupled to receive a plurality of control input signals and a plurality of periodic input signals. The control input signals are derived from the control output signals. Each of the periodic input signals have a different phase. The phase shift circuit applying the control input signals to select from among the periodic input signals to generate a periodic output signal. The periodic output signal being one of the first and second signals.
摘要:
An on-chip resistance to an input current of an input signal includes a parallel transistor resistor and a control circuit for biasing the transistors of the parallel transistor resistor. The parallel transistor resistor includes first and second transistors of first and second types. Each transistor includes first and second current handling terminals and a control terminal. The control terminals are coupled to receive control signals from the control circuit. The first current handling terminals are coupled to provide an input node for receiving an input signal, and the second current handling terminals are coupled to provide an output signal. The control circuit is coupled to provide the first and second control signals for biasing the respective first and second transistors so that a first derivative of a resistance of the parallel transistor resistor in relation to an input-to-output voltage is zero at a selectable operation point.
摘要:
A low-pass filter to filter the internal bias voltages. It is connected locally at the bias voltage input of each bias current source the low-pass filter reduces the AC overshoot oscillations of a local bias voltage generated by the bias voltage generator upon a changing in the amount of current sourced by other current sources. A single bias voltage generator is connected to a bias voltage input of a number of bias current sources. Each current source has a low pass filter to filter the bias voltage.
摘要:
A clock buffer circuit utilizing an LC circuit for jitter reduction. The circuit includes a differential amplifier that is coupled to a buffer stage. The output of the buffer circuit comprises the buffer stage output. An inductor and capacitor are coupled between the buffer stage output and ground. The values of the inductor and capacitor are specified such that the resonant frequency of the LC circuit corresponds to the nominal clock frequency. The entire buffer circuit including the capacitor and inductor may be fabricated on an integrated circuit. Alternatively the capacitor and/or inductor may comprise discrete components that are coupled to the buffer stage output. Additionally, multiple capacitors and/or inductors may be fabricated on the integrated circuit to permit the resonant frequency of the LC circuit to be adjusted to match the nominal clock frequency. The capacitor(s) and/or inductor(s) on the integrated circuit may be connected to integrated circuit contacts and coupled to the buffer stage output via external connections or alternatively, via semiconductor switches.