Patents by Inventor William Pierce Evans

William Pierce Evans has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 8957802
    Abstract: A system and method are provided for the detection and correction of metastability errors in a successive approximation analog to digital converter (ADC). The successive approximation ADC (40) includes a comparator unit (424) that includes a NAND gate circuit (550) that outputs a comp_rdy_n signal when the comparator (500) has latched a result. ADC (40) includes a metastability detection and correction circuit (425) that includes a first logic circuit (700) that monitors the comp_rdy_n signal and detects a metastable event if that signal is not received within a portion of a conversion time period of the ADC. Responsive to detection of a metastable event, a second logic circuit (750) generates a correct conversion code at the output of the ADC. If no metastable event is detected during a conversion cycle of the ADC, the second logic circuit (750) outputs the conversion codes determined by the comparator (500).
    Type: Grant
    Filed: September 13, 2013
    Date of Patent: February 17, 2015
    Assignee: Cadence Design Systems, Inc.
    Inventor: William Pierce Evans
  • Patent number: 8902093
    Abstract: An analog to digital converting system (200) includes an analog to digital converter (ADC) circuit that is formed by a plurality of parallel ADCs (ADC 1 ADC N) for continuous sequential processing of an input analog voltage signal. Each of the ADCs is a type that employs a capacitor digital to analog converter (DAC) (209, 701) therein. The system further includes a sample and hold circuit (220) coupled to the parallel ADCs by a conductive interconnect wiring pattern (203). The sample and hold circuit includes a sampling switch (207) and a hold capacitance formed by the parallel combination of a hold capacitor (205) and the distributed parasitic capacitance (204) of the conductive interconnect wiring pattern (203). During the hold phase of the sample and hold circuit, charge is redistributed from the hold capacitance to all of the capacitors (211) of the capacitor DAC, which serve as a secondary hold capacitance.
    Type: Grant
    Filed: December 5, 2012
    Date of Patent: December 2, 2014
    Assignee: Cadence Design Systems, Inc.
    Inventors: Adrian Luigi Leuciuc, William Pierce Evans
  • Patent number: 8810301
    Abstract: A system and method are provided for level shifting signals generated by an electronic circuit with selectively controlled frequency response. A first circuit portion defines a primary path for a signal within an upper region of a predefined signal frequency range, and includes a first capacitor unit establishing a voltage level shift for a signal passing therethrough. A second circuit portion selectively defines a secondary path bypassing the primary path for a signal within a lower region of the predefined signal frequency range, and includes a switched capacitive section disposed in parallel across the first capacitor unit to establish a voltage level shift for the signal passing therethrough. A second capacitor unit charges substantially to a predetermined shift voltage in a charging phase and couples to the first capacitor unit during a transfer phase. An attenuation adjust unit adjustably augments a parasitic capacitance of the first or second circuit portion.
    Type: Grant
    Filed: June 22, 2012
    Date of Patent: August 19, 2014
    Assignee: Cadence Design Systems, Inc.
    Inventors: William Pierce Evans, Michael Casas
  • Patent number: 8344925
    Abstract: A system and method are provided for adaptively controlling timing in SAR ADC of a sampled analog signal within a conversion period. A state machine maintains a set of SAR states including a sampling state and a plurality of bit conversion states. A reference generator generates a quantization level reference for each of the bit conversion states within a parametric settling time thereof. A comparator compares the sampled analog signal with the quantization level reference over a parametric propagation time for determining a hit value for each hit conversion state. A clock generator adaptively defines signals for clocking the state machine and comparator for each SAR state, thereby adaptively delaying bit determination in each bit conversion state by an integration period not less than the settling time, while adaptively delaying quantization level reference generation for a next bit conversion state by a regeneration period not less than the propagation time.
    Type: Grant
    Filed: May 26, 2011
    Date of Patent: January 1, 2013
    Assignee: Cadence Design Systems, Inc.
    Inventor: William Pierce Evans
  • Patent number: 8081024
    Abstract: A CMOS phase interpolation system comprises a capacitive integration unit coupled to a charge node and a plurality of selectively enabled current source units operably coupled to the charge node. The current source units each include: a charging segment; a discharging segment; and, a switching segment operable responsive to at least one periodic reference signal to selectively couple the charging and discharging segments to the charge node for alternatively charging and discharging the capacitive integration unit therethrough. The current source units are selectively enabled in predetermined combinations to uniquely define an output waveform at the charge node. An output conditioning unit coupled to the charge node generates a recovered periodic signal based on the output waveform. In certain applications, a duty cycle correction unit coupled to feed back from the output node adaptively biases a charging segment current of each enabled current source unit, responsive to the recovered periodic signal.
    Type: Grant
    Filed: December 17, 2009
    Date of Patent: December 20, 2011
    Assignee: Cadence Design Systems, Inc.
    Inventor: William Pierce Evans
  • Patent number: 7948270
    Abstract: The serial interface operable, for example, to facilitate high speed differential data transfer between integrated circuits provides level shifting of an incoming data signal using a switched capacitor technique which level shifts the common mode voltage with minimal attenuation and minimal reduction of bandwidths. The serial interface also includes a DC offset correction loop of the input data receiver path. The level shifting circuit operates by sensing the incoming common mode voltage of a differential data signal with a resistor divider and sampling the difference between the measured input common mode voltage and desired input differential voltages generated by a differential DAC in the DC offset correction loop on two small capacitors.
    Type: Grant
    Filed: December 29, 2009
    Date of Patent: May 24, 2011
    Assignee: Cadence Design Systems, Inc.
    Inventors: William Pierce Evans, Adrian Leuciuc