A power-on reset (POR) circuit includes first, second and third resistors. A first transistor has a first control terminal and first and second voltage terminals. A second transistor has a second control terminal and third and fourth voltage terminals. A third transistor has a third control terminal and fifth and sixth voltage terminals. The first control terminal is coupled via the first resistor to the second voltage terminal. The third voltage terminal is coupled via the second resistor to the first voltage terminal. The second control terminal is coupled via the third resistor to the fourth voltage terminal. The third control terminal is coupled to the third voltage terminal. The fifth voltage terminal is coupled to the first control terminal. A voltage buffer is coupled to the fifth voltage terminal.

A circuit includes first and second power domains. The first power domain has a first power supply voltage level and includes a master latch, a first level shifter, and a slave latch coupled between the master latch and the first level shifter. The second power domain has a second power supply voltage level different from the first power supply voltage level and includes a retention latch coupled between the slave latch and the first level shifter, and the retention latch includes a second level shifter.

A system and method for efficiently retaining data in sequential elements during power down modes. In various embodiments, a master latch of a flip-flop circuit receives an always-on first power supply voltage, whereas, a slave latch and other surrounding circuitry receives a second power supply voltage capable of being powered down. During a power down mode, circuitry consumes less power while the master latch retains stored data. In some designs, the flip-flop circuit is a level shifting circuit, and the always-on first power supply voltage is less than the second power supply voltage. The master latch uses complex gates with a p-type transistor at the top of a stack of p-type transistors receiving the always-on power supply voltage level on its source terminal and the retained data value on its gate terminal. This top p-type transistor is capable of remaining disabled even when used in a level shifting manner.

A master-slave D flip-flop is disclosed having gates configured to supply two second intermediate signals as a function of first intermediate signals and a clock signal, and a slave circuit connected to a transfer circuit to form at least one output signal of the flip-flop from the second intermediate signals. The slave circuit is configured, when the second intermediate signals have, after a preceding pair of states, a predetermined pair of states, to maintain the at least one output signal as given by the preceding pair of states. The transfer circuit has a control input and is configured to generate the second intermediate signals to have the predetermined pair of states in response to a predetermined control signal state at the control input.

A semiconductor circuit includes a first circuit to apply an inverted voltage of a voltage at a first node to a second node, a second circuit to apply an inverted voltage of a voltage at the second node to the first node, a first transistor that includes a gate, a drain, and a source, and stores a threshold state, a second transistor that couples the first node to a first terminal by being turned on, a third transistor that couples a first predetermined node to the gate of the first transistor, and a driving section that controls operations of the second transistor and the third transistor, and applies a control voltage to a second terminal. The first terminal is one of the drain or the source of the first transistor. The second terminal is another of the drain or the source of the first transistor.

A flip-flop includes an input switching circuit configured to output an intermediate signal based on an input signal and at least one of a phase of a clock signal or a phase of an inverted clock signal, the phase of the inverted clock signal being opposite to the phase of the clock signal, and block application of a driving voltage to at least one circuit element of the input switching circuit in response to receiving a reset signal representing a reset operation of the flip-flop, and a latch circuit configured to generate an output signal based on the intermediate signal according to the at least one of the phase of the clock signal or the phase of the inverted clock signal.

A circuit includes a slave latch including a first input and an output, the first input being coupled to a master latch, and a retention latch including a second input coupled to the output. The master latch and the slave latch are configured to operate in a first power domain having a first power supply voltage level, the retention latch is configured to operate in a second power domain having a second power supply voltage level different from the first power supply voltage level, and the circuit further includes a level shifter configured to shift a signal level from one of the first power supply voltage level or the second power supply voltage level to the other of the first power supply voltage level or the second power supply voltage level.

A device (1) for delivering a signal (por_out) switching from a first state to a second state, comprising: a primary circuit (4) generating a primary signal (por_ana); and a secondary circuit (6) configured to: when the primary signal (por_ana) is initialized to the second state upon power-up, initialize a ring counter (16) to a random value comprised in a finite sequence comprising a reference value (INIT), change the value of the first ring counter (16) by running through the first finite sequence in a circular fashion, deliver at an output (3): i) a secondary signal in the first state, when the value of the first counter is different from the reference value (INIT), and ii) the primary signal (por_ana), when the value of the first counter is equal to the reference value (INIT).

The present invention provides a voltage difference measurement circuit comprising a level shifting circuit, an ADC and a calculation circuit. In the operations of the voltage difference measurement circuit, the level shifting circuit adjusts levels of a supply voltage and a ground voltage to generate an adjusted supply voltage and an adjusted ground voltage, respectively. The ADC performs an analog-to-digital converting operation upon the adjusted supply voltage and the adjusted ground voltage to generate a first digital value and a second digital value, respectively. The calculation circuit calculates a voltage difference between the supply voltage and the ground voltage according to the first digital value and the second digital value.

A system and method for efficiently retaining data in sequential elements during power down modes. In various embodiments, a master latch of a flip-flop circuit receives an always-on first power supply voltage, whereas, a slave latch and other surrounding circuitry receives a second power supply voltage capable of being powered down. During a power down mode, circuitry consumes less power while the master latch retains stored data. In some designs, the flip-flop circuit is a level shifting circuit, and the always-on first power supply voltage is less than the second power supply voltage. The master latch uses complex gates with a p-type transistor at the top of a stack of p-type transistors receiving the always-on power supply voltage level on its source terminal and the retained data value on its gate terminal. This top p-type transistor is capable of remaining disabled even when used in a level shifting manner.