Freescale Semiconductor,inc.

Globalfoundries U.S. Inc.

Motorola Corporation

Globalfoundries Inc.

Dzung T Tran

Kiyoshi Kase

May Len

Shibly S Ahmed

Navneet Jain

Shivraj Gurpadappa Dharne

Sushama Davar

Rakesh Pandey

Fujio Takeda

Geoffrey B Hall

Pedro Ovalle

Rishi Bhooshan

Uttam K Saha

Asif Iqbal

Trong D Nguyen

Deepti A Pant

Kase Kiyoshi

Disclosed is an input buffer with hysteresis-integrated voltage protection devices for avoiding violations of maximum gate-to-source voltage limitations when the maximum input voltage is greater than the maximum gate-to-source voltage limitation. The input buffer includes a chain of transistors including two P-channel FETs (PFETs) and two N-channel FETs (NFETs). The data input to the input buffer controls the gates of the transistors in the chain so the data output from the input buffer at the junction between the PFETs and NFETs is inverted. The input buffer also includes a hysteresis feedback loop to prevent noise-induced switching of the output. The hysteresis feedback loop also includes voltage protection devices integrated therein to avoid maximum gate-to-source violations when the loop results in a hysteresis voltage being fed back into the chain at the source region of a transistor in the chain. Also disclosed is a receiver incorporating the input buffer.

Input buffer with hysteresis-integrated voltage protection devices and receiver incorporating the input buffer

Embodiments of the disclosure provide a structure and method to ground a reference voltage generator based on a detected supply voltage. A circuit structure according to the disclosure includes a pass gate. The pass gate includes a pair of transistors each coupled to an input signal. One of the pair of transistors of the pass gate includes a gate coupled to a static reference voltage. An inverter couples an output from the pass gate to a device node. The inverter includes a drain terminal, a gate terminal, and a back-gate terminal coupled to ground.

Structure and method to ground reference voltage generator

A disclosed flip-flop includes primary and secondary sections connected to switchable and continuous power supplies, respectively. The primary section includes logic outputting first control signals, a primary latch controlled by the first control signals, and a data output device connected to an output terminal of the primary latch. The secondary section includes logic outputting second control signals and a secondary latch. A first transmission gate controlled by the second control signals is connected between the output terminal of the primary latch and an input terminal of the secondary latch. A second transmission gate controlled by the first and second control signals is connected between output and input terminals of the secondary latch. In a normal mode, both sections receive power and the first transmission gate is conductive. In a retention mode, the primary section is powered down, the first transmission gate is non-conductive and the second transmission gate is conductive.

Retention flip-flop with multiple positive supply voltage domains

A reference circuit for an electronic device having a plurality of power supply voltages comprises a supply start-up circuit, a power-down start-up circuit, and a reference generating circuit. The supply start-up circuit comprising a resistive-capacitive (RC) circuit coupled between a first power supply voltage and a ground. The RC circuit includes a pulse node coupled between a first capacitor and a resistive element, and generates a power-up pulse signal at the pulse node. The power-down start-up circuit is powered by a second power supply voltage and comprises a pulse generation circuit that generates a first start-up signal. The reference generating circuit outputs a reference signal. The reference generating circuit exists a low-power mode when either of the power-up pulse signal and the first start-up signal is generated.

Circuit and method for start-up of reference circuits in devices with a plurality of supply voltages

The present disclosure relates to a structure including a level shifter circuit which receives an input signal and at least one voltage reference signal and outputs at least one level shifted output signal, a pre-driver circuit which receives the at least one level shifted output signal and outputs at least one pre-driver output signal, the pre-driver circuit including at least one delay circuit, and a main driver circuit which receives the at least one pre-driver output signal and outputs a main driver output signal.

Output buffer circuit

Embodiments of the disclosure provide an input output (IO) structure in which complimentary nodes of a level shifter are utilized to logically block the output of the IO structure from switching until both power supplies to the IO structure are powered up. An illustrative level shifter includes: a cross-coupled pair of PFETs configured to output complimentary voltage values at a first node and a second node; a control circuit configured to select which of the complementary voltage values are output to the first node and second node; a logic inverter having an input coupled to the first node and an output coupled to a third node; and a NAND gate having inputs coupled to the second node and third node and that generates a level shifted output.

Low power power-up reset output driver

A disclosed pre-driver circuit includes multiple signal generation stages configured to receive different bias voltages from local switching bias circuit(s). In some embodiment, pre-driver circuit has multiple switching bias circuits, each with a bias voltage node connected to a corresponding stage. In other embodiments, the pre-driver circuit has a single switching bias circuit with multiple bias voltage nodes and a multi-input/multi-output multiplexor with inputs connected to the bias voltage nodes and outputs connected to the stages. The switching bias circuit(s) and a primary inverter in each stage all receive the same input signal. When this input signal transitions, the switching bias circuit(s) supply bias voltages to the stages and the primary inverters turn on in sequence and slowly, thereby ensuring that pre-driver signals generated by the different stages transition in sequence and at a relatively slow rate. Once the last pre-driver signal transitions, the switching bias circuit(s) turn off.

Pre-driver circuits for an output driver

A disclosed pre-driver includes multiple signal generation stages and a switching bias circuit with a first switch and a second switch. The first switch and primary inverters in each of the stages all receive the same input signal. When the input signal transitions, the first switch turns on the bias circuit to supply a bias voltage to each of the stages. However, the primary inverters do not concurrently turn on. Instead, due to the bias voltage and some additional circuitry within each stage, the primary inverters turn on in sequence and slowly, thereby ensuring that pre-driver signals generated and output by the different stages, respectively, transition in sequence and at a relatively slow rate. Once the last pre-driver signal transitions, the second switch turns off the switching bias circuit. Optionally, a selected one of multiple bias voltages could be used in order to tune delay and transition times.

An integrated circuit includes an input/output pad, an input circuit, and an output circuit. The input circuit is coupled to the input/output pad that receives input signals including a wake-up signal that indicates when the integrated circuit is to switch from a power-down mode to an active mode. The output circuit is coupled to the input/output pad that provides output signals to the input/output pad. The output circuit includes a first P channel transistor in a well having a drain coupled to the input/output pad, and a source coupled to a power supply terminal. The power supply terminal receives a first power supply voltage during the active mode and is decoupled from any power supply during the power-down mode. The well is coupled to the wake-up signal in response to the wake-up signal indicating a change from the power-down mode to the active mode.

Processing system with low power wake-up pad

Dual-voltage detectors and related methods are disclosed that receive control signals from a first supply voltage domain and provide multiple disable outputs within a separate supply voltage domain. The disclosed embodiments detect a power supply status in one supply voltage domain (e.g., 1.2 volts, ground) and then assert low voltage disable or reset signals to downstream circuitry within a different supply voltage domain that is powered with different supply voltages (e.g., 1.8 volts, 0.9 volts, ground). In certain embodiments, the dual-voltage detectors provide two disable signals to stacked output drivers that are used to tri-state the stacked output drivers to place them in a high-impedance (HIGH-Z) state, for example, during power-up or power-down operations.

Dual-voltage detector having disable outputs within separate voltage domain and related methods

A current boost module receives a signal from the input and the output of a buffer to determine whether the buffer is transitioning between logic states. When the buffer is transitioning, a boost current is provided to a load connected to the buffer output to supplement the current from buffer output, thereby facilitating transition of a signal at the load. The current boost module can shut down the boost current before the signal at the load completes its transition from one logic state to the other.

Electronic device and method

Methods and corresponding systems for buffering an input signal include outputting a first logic value in response to the input signal being below a lower threshold. A second logic value is output in response to the input signal rising above the lower threshold. Thereafter, the second logic value is maintained until the input exceeds a higher threshold and thereafter falls below the higher threshold. In response to the input signal falling below the higher threshold, the first logic value is output, and maintained at the first logic value, until the input falls below the lower threshold and thereafter rises above the lower threshold.

Input buffer

A circuit's performance may vary based on various factors such as, for example, process, voltage, and/or temperature. In one embodiment, a circuit includes an input terminal which receives an input signal, a delay selection section which delays the input signal by a delay amount selected by a performance variation indicator, an impedance selection section which outputs the delayed input signal as a compensated delayed signal, where the impedance selection section uses a driver impedance amount selected by the performance variation indicator, and an output terminal which outputs the compensated delayed signal. The circuit may also include a ring oscillator, a frequency counter which provides a count value which indicates a number of rising edges of an output of the ring oscillator which occur during a period of a reference frequency, and a decoder which uses the count value to output the performance variation indicator.

Performance variation compensating circuit and method

In one form a circuit has a bias stage having an input signal terminal for receiving an input signal. The circuit modifies the input signal with a drive stage to provide an output signal in complement form. A drive transistor in the drive stage of the circuit has a bulk that is connected to a terminal of a load and to a control electrode coupled to the input signal terminal. A bias transistor in the bias stage of the circuit has a bulk that is directly connected to the terminal of the load and to the bulk of the drive transistor. The bias transistor has a control electrode coupled to the input signal terminal. The input signal biases the bulks of the drive transistor and the bias transistor and reduces transistor threshold voltage. Linearity of circuit output impedance is improved and RF interference reduced. Lower voltage operation is also provided.

Low voltage circuit with variable substrate bias

A voltage control circuit includes a first transistor coupled to a first voltage supply terminal having a first voltage, a second transistor coupled to the first transistor and a node, a third transistor coupled to a second voltage supply terminal and the node, wherein the second voltage supply terminal has a second voltage and the node is at a voltage selected from the group consisting of the first voltage and the second voltage, and a fourth transistor coupled to the node.

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Austin, TX, United States of America

Dzung T Tran