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).
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Patent number: 8587365Abstract: Disclosed is an improved substrate bias feedback circuit, and a method for operating the same.Type: GrantFiled: October 9, 2012Date of Patent: November 19, 2013Assignee: Cypress Semiconductor CorporationInventors: Vijay Kumar Srinivasa Raghavan, Iulian C. Gradinariu
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Patent number: 8283972Abstract: 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: GrantFiled: December 13, 2011Date of Patent: October 9, 2012Assignee: Cypress Semiconductor CorporationInventors: Vijay Kumar Srinivasa Raghavan, Iulian Gradinariu
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Patent number: 8279677Abstract: 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: GrantFiled: August 9, 2011Date of Patent: October 2, 2012Assignee: Cypress Semiconductor Corp.Inventor: Vijay Kumar Srinivasa Raghavan
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Patent number: 8217713Abstract: 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: GrantFiled: October 22, 2007Date of Patent: July 10, 2012Assignee: Cypress Semiconductor CorporationInventors: Vijay Kumar Srinivasa Raghavan, Cristinel Zonte
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Patent number: 8085085Abstract: 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: GrantFiled: June 28, 2010Date of Patent: December 27, 2011Assignee: Cypress Semiconductor CorporationInventors: Vijay Kumar Srinivasa Raghavan, Iulian Gradinariu
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Patent number: 7995397Abstract: 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: GrantFiled: May 5, 2008Date of Patent: August 9, 2011Assignee: Cypress Semiconductor CorporationInventor: Vijay Kumar Srinivasa Raghavan
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Patent number: 7929363Abstract: 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: GrantFiled: March 12, 2008Date of Patent: April 19, 2011Assignee: Cypress Semiconductor CorporationInventors: Vijay Kumar Srinivasa Raghavan, Leonard Gitlan
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Patent number: 7852144Abstract: 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: GrantFiled: September 28, 2007Date of Patent: December 14, 2010Assignee: Cypress Semiconductor CorporationInventors: Cristinel Zonte, Vijay Kumar Srinivasa Raghavan
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Patent number: 7821866Abstract: 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: GrantFiled: November 14, 2007Date of Patent: October 26, 2010Assignee: Cypress Semiconductor CorporationInventors: Vijay Kumar Srinivasa Raghavan, Ryan Hirose
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Patent number: 7821859Abstract: 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: GrantFiled: October 9, 2007Date of Patent: October 26, 2010Assignee: Cypress Semiconductor CorporationInventor: Vijay Kumar Srinivasa Raghavan
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Patent number: 7808842Abstract: 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: GrantFiled: September 9, 2008Date of Patent: October 5, 2010Assignee: Cypress Semiconductor CorporationInventors: Vijay Kumar Srinivasa Raghavan, Cristinel Zonte
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Patent number: 7746160Abstract: Disclosed is an improved substrate bias feedback circuit, and a method for operating the same.Type: GrantFiled: February 26, 2009Date of Patent: June 29, 2010Assignee: Cypress Semiconductor CorporationInventors: Vijay Kumar Srinivasa Raghavan, Iulian Gradinariu
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Patent number: 7710803Abstract: 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: GrantFiled: March 31, 2008Date of Patent: May 4, 2010Assignee: Cypress Semiconductor CorporationInventor: Vijay Kumar Srinivasa Raghavan
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Patent number: 7586333Abstract: 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: GrantFiled: December 20, 2007Date of Patent: September 8, 2009Assignee: Cypress Semiconductor CorporationInventors: Vijay Kumar Srinivasa Raghavan, Ryan Tasuo Hirose
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Patent number: 7545694Abstract: 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: GrantFiled: August 16, 2007Date of Patent: June 9, 2009Assignee: Cypress Semiconductor CorporationInventors: Vijay Kumar Srinivasa Raghavan, Ryan Tasuo Hirose
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Patent number: 7504876Abstract: Disclosed is an improved substrate bias feedback circuit, and a method for operating the same.Type: GrantFiled: June 28, 2006Date of Patent: March 17, 2009Assignee: Cypress Semiconductor CorporationInventors: Vijay Kumar Srinivasa Raghavan, Iulian Gradinariu
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Patent number: 7471135Abstract: 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: GrantFiled: December 5, 2006Date of Patent: December 30, 2008Assignee: Cypress Semiconductor Corp.Inventors: Vijay Kumar Srinivasa Raghavan, Ryan Tasuo Hirose
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Publication number: 20080130375Abstract: 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: ApplicationFiled: December 5, 2006Publication date: June 5, 2008Applicant: CYPRESS SEMICONDUCTOR CORP.Inventors: Vijay Kumar Srinivasa Raghavan, Ryan Tasuo Hirose
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Patent number: 7362163Abstract: 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: GrantFiled: March 4, 2005Date of Patent: April 22, 2008Assignee: Cypress Semiconductor CorpInventor: Vijay Kumar Srinivasa Raghavan
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Publication number: 20080042691Abstract: 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: ApplicationFiled: August 16, 2007Publication date: February 21, 2008Inventors: Vijay Kumar Srinivasa Raghavan, Ryan Tasuo Hirose