Patents by Inventor Vijay Kumar Srinivasa Raghavan

Vijay Kumar Srinivasa Raghavan 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: 8587365
    Abstract: Disclosed is an improved substrate bias feedback circuit, and a method for operating the same.
    Type: Grant
    Filed: October 9, 2012
    Date of Patent: November 19, 2013
    Assignee: Cypress Semiconductor Corporation
    Inventors: Vijay Kumar Srinivasa Raghavan, Iulian C. Gradinariu
  • Patent number: 8283972
    Abstract: A method of biasing a circuit includes generating a control bias signal based on a difference between a leakage current of a baseline circuit and a reference signal; applying the control bias signal to a charge pump circuit to set a value of a reverse body bias voltage output from the charge pump, the control bias signal providing analog control of a digital clock of the charge pump circuit; and applying the reverse body bias voltage to a body of the baseline circuit.
    Type: Grant
    Filed: December 13, 2011
    Date of Patent: October 9, 2012
    Assignee: Cypress Semiconductor Corporation
    Inventors: Vijay Kumar Srinivasa Raghavan, Iulian Gradinariu
  • Patent number: 8279677
    Abstract: A SONOS memory sensing scheme includes a reference current circuit that tracks the changes in the power supply (Vcc). An equalizer of the current sense amplifier is coupled between the read out current line and the reference current line. The current sense amplifier includes data and datab (data bar) outputs which have a common mode noise due to variations in the power supply voltage. The data output is a current generated from the memory cell, and the datab output is generated by the current reference circuit.
    Type: Grant
    Filed: August 9, 2011
    Date of Patent: October 2, 2012
    Assignee: Cypress Semiconductor Corp.
    Inventor: Vijay Kumar Srinivasa Raghavan
  • Patent number: 8217713
    Abstract: A device for providing a high precision current reference comprising a PTAT generator circuit for supplying a voltage, a high precision current reference offset generator circuit for generating a high precision current offset to compensate for variation in a resistance component due to variation in temperature, and a current adding circuit for aggregating the current from the PTAT generator circuit and the current from the high precision current reference offset generator circuit. In one embodiment, a high precision current reference generated is substantially independent of temperature. On-chip resistors may be used to design a high precision current reference. Accordingly, high precision current reference generated maintains high precision with zero temperature co-efficient using on-chip resistors that are substantially cheaper than off-chip resistors.
    Type: Grant
    Filed: October 22, 2007
    Date of Patent: July 10, 2012
    Assignee: Cypress Semiconductor Corporation
    Inventors: Vijay Kumar Srinivasa Raghavan, Cristinel Zonte
  • Patent number: 8085085
    Abstract: A substrate bias circuit may measure a leakage current of a baseline device, compare the leakage current with a reference current, and based on the comparison, adjust a reverse body bias voltage applied to a body of the baseline device.
    Type: Grant
    Filed: June 28, 2010
    Date of Patent: December 27, 2011
    Assignee: Cypress Semiconductor Corporation
    Inventors: Vijay Kumar Srinivasa Raghavan, Iulian Gradinariu
  • Patent number: 7995397
    Abstract: A SONOS memory sensing scheme includes a reference current circuit that tracks the changes in the power supply (Vcc). An equalizer of the current sense amplifier is coupled between the read out current line and the reference current line. The current sense amplifier includes data and datab (data bar) outputs which have a common mode noise due to variations in the power supply voltage. The data output is a current generated from the memory cell, and the datab output is generated by the current reference circuit.
    Type: Grant
    Filed: May 5, 2008
    Date of Patent: August 9, 2011
    Assignee: Cypress Semiconductor Corporation
    Inventor: Vijay Kumar Srinivasa Raghavan
  • Patent number: 7929363
    Abstract: A method of optimizing memory cell write/read is disclosed. The memory cell write/read is optimized by first reading the memory cell data using the normal mode. Next the page latch data that was used to NV (Non-Volatile) write the memory is also read back directly from the page latches. The two data are then compared to verify a successful and optimized memory cell write/read. NV writes and reads are performed with various high voltage parameters and sense amplifier reference settings to arrive at the most optimal one that gives the largest sense window for best write/read reliability. The page latch read mode is also used as a DFT (Design for Test) test mode to check for page latch functionality and page address uniqueness without having to write the memory cell. The page latch is written with logic data and read out directly using the page latch read mode to verify page functionality.
    Type: Grant
    Filed: March 12, 2008
    Date of Patent: April 19, 2011
    Assignee: Cypress Semiconductor Corporation
    Inventors: Vijay Kumar Srinivasa Raghavan, Leonard Gitlan
  • Patent number: 7852144
    Abstract: A relatively precise and accurate current reference system and method are described. The present current reference system and method facilitate realization of relatively high accuracy and precision in current references independent of process, voltage and temperature (PVT) variations. In one embodiment, a current reference system includes an opamp (operational amplifier), a first transistor and second transistor, a first resistor and a second resistor of different temperature coefficients, and a third transistor and fourth transistor. The opamp indicates and corrects the potential difference between a first branch and a second branch. The first transistor and second transistor mirror currents in the first branch and the second branch. The first resistor and a second resistor of different temperature coefficients cause voltage drops across them in a manner that compensates for PTAT variations. The third transistor and fourth transistor provide voltages between respective bases and emitters.
    Type: Grant
    Filed: September 28, 2007
    Date of Patent: December 14, 2010
    Assignee: Cypress Semiconductor Corporation
    Inventors: Cristinel Zonte, Vijay Kumar Srinivasa Raghavan
  • Patent number: 7821866
    Abstract: The invention has a bootstrapped high voltage pass gate transistor that couples the low voltage sense amplifier to the bitlines. Since the pass gate transistor is bootstrapped its gate floats to the high voltage of the power supply (VCC) plus a delta voltage. This overdrives the pass gate transistor and allows it to pass signals between the sense amplifier and the bitlines with low impedance. This results in good sense differential margins and fast read speeds. The circuit has a pass gate control circuit that places a negative high voltage signal on the gate of the pass gate during non-volatile write operations. This causes the pass gate to isolate the low voltage circuit from the high voltage circuits during this operation. Finally, the circuit is smaller than earlier column multiplexer circuits.
    Type: Grant
    Filed: November 14, 2007
    Date of Patent: October 26, 2010
    Assignee: Cypress Semiconductor Corporation
    Inventors: Vijay Kumar Srinivasa Raghavan, Ryan Hirose
  • Patent number: 7821859
    Abstract: A current sense amplifier can include an active load circuit having a first load device and second load device coupled in parallel to a first power supply node. A first load device and second load device can provide an impedance that varies according to a potential at a load control node. A reference current circuit can be coupled between the first load device and a second power supply node that includes a current reference section that provides an impedance according to a bias voltage. A data current circuit can be coupled between the second load device and a plurality of memory cells. An adaptive bias circuit can be coupled between the first power supply and the second power supply node and can include a bias section coupled to the load control node that provides an impedance according to the bias voltage.
    Type: Grant
    Filed: October 9, 2007
    Date of Patent: October 26, 2010
    Assignee: Cypress Semiconductor Corporation
    Inventor: Vijay Kumar Srinivasa Raghavan
  • Patent number: 7808842
    Abstract: System and methods to adjust a reference current are disclosed. A current reference circuit generates an adjustable reference current. A microprocessor-based feedback circuit adjusts the reference current, wherein the adjustment is based on read and write parameters attributed to a memory cell.
    Type: Grant
    Filed: September 9, 2008
    Date of Patent: October 5, 2010
    Assignee: Cypress Semiconductor Corporation
    Inventors: Vijay Kumar Srinivasa Raghavan, Cristinel Zonte
  • Patent number: 7746160
    Abstract: Disclosed is an improved substrate bias feedback circuit, and a method for operating the same.
    Type: Grant
    Filed: February 26, 2009
    Date of Patent: June 29, 2010
    Assignee: Cypress Semiconductor Corporation
    Inventors: Vijay Kumar Srinivasa Raghavan, Iulian Gradinariu
  • Patent number: 7710803
    Abstract: A circuit and method for testing address uniqueness of a memory array are disclosed. The circuit includes a plurality of current sinks associated with rows and columns of the memory array. A plurality of word lines of the memory array are coupled to the plurality of current sinks. A current mirror circuit is coupled to the plurality of current sinks and a circuit output node is coupled to the current mirror circuit. The circuit output node is configured to compare a total current from tested word lines of the memory array with a predetermined reference current, and to output a test pass or test fail indication in response to the comparison.
    Type: Grant
    Filed: March 31, 2008
    Date of Patent: May 4, 2010
    Assignee: Cypress Semiconductor Corporation
    Inventor: Vijay Kumar Srinivasa Raghavan
  • Patent number: 7586333
    Abstract: Disclosed are a circuit and a method for a high speed, low supply voltage tolerant bootstrapped word line driver with high voltage isolation. The circuit includes a low voltage driver. A gate bootstrapped transistor is coupled to the low voltage driver. A first transistor is coupled to an output terminal of the gate bootstrapped transistor. A substrate of the first transistor is coupled to a negative bias signal. A second transistor is coupled to a gate terminal of the gate bootstrapped transistor. A substrate of the first transistor is coupled to a negative bias signal.
    Type: Grant
    Filed: December 20, 2007
    Date of Patent: September 8, 2009
    Assignee: Cypress Semiconductor Corporation
    Inventors: Vijay Kumar Srinivasa Raghavan, Ryan Tasuo Hirose
  • Patent number: 7545694
    Abstract: Disclosed is a high speed and power efficient dual mode sense amplifier circuit, which comprises a configuration selector further comprising a read amplifier, a debug circuit and a backup read circuit. The dual mode sense amplifier circuit also comprises a controllable input node further comprising an enabling circuit, the controllable input node being coupled to the configuration selector and the dual mode sense amplifier circuit comprises a differential signal generator further comprising a reference signal source, the differential signal generator is coupled to the controllable input node. A method of dual mode sensing and other embodiments are also disclosed.
    Type: Grant
    Filed: August 16, 2007
    Date of Patent: June 9, 2009
    Assignee: Cypress Semiconductor Corporation
    Inventors: Vijay Kumar Srinivasa Raghavan, Ryan Tasuo Hirose
  • Patent number: 7504876
    Abstract: Disclosed is an improved substrate bias feedback circuit, and a method for operating the same.
    Type: Grant
    Filed: June 28, 2006
    Date of Patent: March 17, 2009
    Assignee: Cypress Semiconductor Corporation
    Inventors: Vijay Kumar Srinivasa Raghavan, Iulian Gradinariu
  • Patent number: 7471135
    Abstract: A multiplexer circuit provided herein includes a plurality of pass devices coupled in parallel between a power supply and a ground supply. According to one embodiment, each pass device may include a first pair of transistors, which is coupled in series between the power supply and the ground supply, and a second pair of transistors, which is coupled to the first pair of transistors for controlling a current passed there through. In general, the second pair of transistors may be configured for increasing the amount of current passed through the first pair of transistors. For example, the second pair of transistors may utilize a bootstrapping effect to increase a pair of control voltages supplied to the gate terminals of the first pair of transistors. The increased control voltages function to over-drive the gate terminals of the first pair of transistors, thereby increasing the amount of current passed there through.
    Type: Grant
    Filed: December 5, 2006
    Date of Patent: December 30, 2008
    Assignee: Cypress Semiconductor Corp.
    Inventors: Vijay Kumar Srinivasa Raghavan, Ryan Tasuo Hirose
  • Publication number: 20080130375
    Abstract: A multiplexer circuit provided herein includes a plurality of pass devices coupled in parallel between a power supply and a ground supply. According to one embodiment, each pass device may include a first pair of transistors, which is coupled in series between the power supply and the ground supply, and a second pair of transistors, which is coupled to the first pair of transistors for controlling a current passed there through. In general, the second pair of transistors may be configured for increasing the amount of current passed through the first pair of transistors. For example, the second pair of transistors may utilize a bootstrapping effect to increase a pair of control voltages supplied to the gate terminals of the first pair of transistors. The increased control voltages function to over-drive the gate terminals of the first pair of transistors, thereby increasing the amount of current passed there through.
    Type: Application
    Filed: December 5, 2006
    Publication date: June 5, 2008
    Applicant: CYPRESS SEMICONDUCTOR CORP.
    Inventors: Vijay Kumar Srinivasa Raghavan, Ryan Tasuo Hirose
  • Patent number: 7362163
    Abstract: Systems and methods of flyback capacitor level shifter feedback regulation for negative pumps. In accordance with a first embodiment of the present invention, a feedback regulator for a negative output charge pump comprises a flyback capacitor for inverting an output of the negative output charge pump to a positive voltage. The feedback regulator further comprises a voltage comparator for comparing the positive voltage to a reference voltage. The voltage comparator is also for producing an enable signal for control of pump driving signals to the negative output charge pump. The feedback regulator further comprises a first plurality of switches for selectively coupling a first terminal of the flyback capacitor between a low voltage and the output and a second plurality of switches for selectively coupling a second terminal of the flyback capacitor between a low voltage and the voltage comparator. Further, the feedback regulator comprises switch control logic for controlling the plurality of switches.
    Type: Grant
    Filed: March 4, 2005
    Date of Patent: April 22, 2008
    Assignee: Cypress Semiconductor Corp
    Inventor: Vijay Kumar Srinivasa Raghavan
  • Publication number: 20080042691
    Abstract: Disclosed is a high speed and power efficient dual mode sense amplifier circuit, which comprises a configuration selector further comprising a read amplifier, a debug circuit and a backup read circuit. The dual mode sense amplifier circuit also comprises a controllable input node further comprising an enabling circuit, the controllable input node being coupled to the configuration selector and the dual mode sense amplifier circuit comprises a differential signal generator further comprising a reference signal source, the differential signal generator is coupled to the controllable input node. A method of dual mode sensing and other embodiments are also disclosed.
    Type: Application
    Filed: August 16, 2007
    Publication date: February 21, 2008
    Inventors: Vijay Kumar Srinivasa Raghavan, Ryan Tasuo Hirose