Sun Microsystems, Inc.

Tri K Tran

Brian W Amick

Claude R Gauthier

Lynn Warriner

Gajendra Prasad Singh

Aparna Ramachandran

Dong Joon Yoon

Cong K Khieu

Shao H Liu

A sense amplifier latch that is operable to interface with high common-mode input voltages with wide ranges for all process variations. The sense amplifier latch comprises a cross-coupled latch having first and second rail signals; a pre-charge device; an equalization device; pass devices for enabling input devices to receive pad and reference inputs. In the present invention, the input devices comprise push-pull impedance dividers are used to preserve the input difference voltage while dramatically lowering the common-mode output voltage. The outputs of the impedance dividers are fed to the cross-coupled latch of the sense amplifier using n-channel pass gates.

Differential sense amplifier latch for high common mode input

A digital delay-locked loop has been discovered having a reduced area as compared to typical register-controlled delay-locked loops (RDLLs) used to control strobe delay lines that provide delay to strobe signals driving asynchronous FIFOs. This result is achieved by reducing ratio computation (i.e. gear logic) circuitry of the RDLL. A master delay line receives a control code to delay a reference clock by one clock period. A slave delay line receives the control code to delay a strobe signal by a predetermined fraction of the clock period. The master delay line may include individual sections responsive to the control code which effectively delay a signal by a portion of the clock period, the delay having a fixed relationship to a delay associated with individual sections of the slave delay line.

Generating different delay ratios for a strobe delay

A digital delay locked loop uses a delay array to delay an input signal by an amount indicated by a delay code. A phase of the resulting delayed signal is compared to a corresponding phase of the input signal, and dependent on the comparison, the delay code is updated to indicate whether the delay array needs to provide more delay or less delay. The digital delay locked loop also uses a detection circuit that monitors for a predetermined condition of the delay code. In response to detection of the predetermined condition, the delay code is automatically reset to a value different than a value of the delay code present at a previous reset or initial startup of the digital delay locked loop.

Digital delay locked loop with extended phase capture range

A SSTL memory interface pre-driver stage that uses a voltage regulator to generate a 'virtual' ground reference voltage is provided. The 'virtual' ground voltage reference, being greater than a zero volt ground voltage, allows low voltage transistors to be used, thereby improving interface performance and decreasing system power consumption. The pre-driver stage uses a biasing circuit to bias the voltage regulator, formed by a transistor arranged in a source follower configuration, to generate the &#x2018;virtual&#x2019; ground reference voltage off which a voltage translator stage of the pre-driver stage operates to generate an output of the pre-driver stage.

SSTL pull-up pre-driver design using regulated power supply

A SSTL interface voltage translator that uses dynamic biasing to translate an input signal to an output signal is provided. The voltage translator uses a first device that, dependent on a first bias signal, causes the output signal to be pulled down, where the first bias signal is dependent on the input signal. The voltage translator also uses a second device that, dependent on a second bias signal, causes the output signal to be pulled up, where the second bias signal is dependent on the input signal.

SSTL voltage translator with dynamic biasing

Disclosed is an input/output (IO) device having a power supply node, an input node for receiving an input data signal, and an output node for outputting an output data signal generated in response to the input node receiving the input data bit signal. The IO device also includes a pull-up driver coupled to the power supply node and the output node, wherein the pull-up driver comprises an impedance at the output node which is constant for all voltages at the output node. Additionally, the IO device may have a circuit coupled to the input node, the pull-up driver, and the output node. This circuit is configured to generate a signal that is provided to the pull-up driver. The signal generated by the circuit varies as a function of the voltage at the output node.

Circuit and method for dynamically controlling the impedance of an input/output driver

A cascode SSTL output buffer using a source follower circuit includes a biasing circuit arranged to generate a first bias signal. The source follower circuit is responsive to the first bias signal and generates a second bias signal which is then used by a cascode circuit that receives an input signal to the SSTL output buffer to drive an output signal from the SSTL output buffer.

Cascode SSTL output buffer using source followers

A SSTL memory interface pre-driver stage that uses a voltage regulator to generate a 'virtual' supply is provided. The 'virtual' supply, being lower than a power supply voltage of the pre-driver stage, allows low voltage transistors to be used, thereby improving interface performance and decreasing system power consumption. The pre-driver stage uses a biasing circuit to bias the voltage regulator, formed by a transistor arranged in a source follower configuration, to generate the &lsquo;virtual&rsquo; supply off which a voltage translator stage of the pre-driver stage operates to generate an output of the pre-driver stage.

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San Leandro, CA, United States of America

Tri K Tran