Abstract: A successive approximation analog-to-digital with an input for receiving an input analog voltage, and an amplifier with a first set of electrical attributes in a sample phase and a second set of electrical attributes, differing from the first set of electrical attributes, in a conversion phase.

Abstract: A successive approximation analog-to-digital with an input for receiving an input analog voltage, and an amplifier with a first set of electrical attributes in a sample phase and a second set of electrical attributes, differing from the first set of electrical attributes, in a conversion phase.

Abstract: A successive approximation analog-to-digital with an input for receiving an input analog voltage, and an amplifier with a first set of electrical attributes in a sample phase and a second set of electrical attributes, differing from the first set of electrical attributes, in a conversion phase.

Abstract: A successive approximation analog-to-digital with an input for receiving an input analog voltage, and an amplifier with a first set of electrical attributes in a sample phase and a second set of electrical attributes, differing from the first set of electrical attributes, in a conversion phase.

Abstract: In described examples, a first and second driver each include a first-rail output transistor including a first terminal coupled to a first power rail and a second-rail output transistor including a first terminal coupled to a second power rail. The first-rail output transistor of each of the first and second drivers includes a second terminal coupled to a second terminal of the second-rail output transistor of an output node of each respective first and second driver. A resistive load includes a first terminal coupled to the first-driver output node and includes a second terminal coupled to the second-driver output node. A sampling circuit generates an indication of an impedance of at least one of the output transistors of the first and second drivers.

Abstract: A circuit includes a first filter, a plurality of binary-weighted capacitors, and a current source device. The circuit also includes a first plurality of switches. Each of the first plurality of switches is connected to a separate capacitor of the plurality of binary-weighted capacitors. The first plurality of switches are connected together, and the first plurality of switches are not connected to the first filter. A second plurality of switches is also included, and each of the second plurality of switches is connected to a separate capacitor of the plurality of binary-weighted capacitors and to the first filter and to a control input of the current source device. The first plurality of switches are not connected to the control input.

Abstract: A circuit includes a first filter, a plurality of binary-weighted capacitors, and a current source device. The circuit also includes a first plurality of switches. Each of the first plurality of switches is connected to a separate capacitor of the plurality of binary-weighted capacitors. The first plurality of switches are connected together, and the first plurality of switches are not connected to the first filter. A second plurality of switches is also included, and each of the second plurality of switches is connected to a separate capacitor of the plurality of binary-weighted capacitors and to the first filter and to a control input of the current source device. The first plurality of switches are not connected to the control input.

Abstract: In some embodiments, an analog-to-digital converter (ADC) comprises a loop filter configured to produce an error signal based on a difference between an analog input signal and a feedback signal. The ADC also comprises a main comparator set comprising one or more main comparators, the main comparator set configured to digitize the error signal and further configured to drive a main digital-to-analog converter (DAC). The ADC further comprises an auxiliary comparator set comprising a plurality of auxiliary comparators, the auxiliary comparator set configured to digitize the error signal when the ADC is in a runaway state and further configured to drive an auxiliary DAC to bring the error signal into a predetermined range.

Abstract: In some embodiments, an analog-to-digital converter (ADC) comprises a loop filter configured to produce an error signal based on a difference between an analog input signal and a feedback signal. The ADC also comprises a main comparator set comprising one or more main comparators, the main comparator set configured to digitize the error signal and further configured to drive a main digital-to-analog converter (DAC). The ADC further comprises an auxiliary comparator set comprising a plurality of auxiliary comparators, the auxiliary comparator set configured to digitize the error signal when the ADC is in a runaway state and further configured to drive an auxiliary DAC to bring the error signal into a predetermined range.

Abstract: In some embodiments, an analog-to-digital converter (ADC) comprises a loop filter configured to produce an error signal based on a difference between an analog input signal and a feedback signal. The ADC also comprises a main comparator set comprising one or more main comparators, the main comparator set configured to digitize the error signal and further configured to drive a main digital-to-analog converter (DAC). The ADC further comprises an auxiliary comparator set comprising a plurality of auxiliary comparators, the auxiliary comparator set configured to digitize the error signal when the ADC is in a runaway state and further configured to drive an auxiliary DAC to bring the error signal into a predetermined range.

Abstract: In described examples, a first and second driver each include a first-rail output transistor including a first terminal coupled to a first power rail and a second-rail output transistor including a first terminal coupled to a second power rail. The first-rail output transistor of each of the first and second drivers includes a second terminal coupled to a second terminal of the second-rail output transistor of an output node of each respective first and second driver. A resistive load includes a first terminal coupled to the first-driver output node and includes a second terminal coupled to the second-driver output node. A sampling circuit generates an indication of an impedance of at least one of the output transistors of the first and second drivers.

Abstract: In some embodiments, an analog-to-digital converter (ADC) comprises a loop filter configured to produce an error signal based on a difference between an analog input signal and a feedback signal. The ADC also comprises a main comparator set comprising one or more main comparators, the main comparator set configured to digitize the error signal and further configured to drive a main digital-to-analog converter (DAC). The ADC further comprises an auxiliary comparator set comprising a plurality of auxiliary comparators, the auxiliary comparator set configured to digitize the error signal when the ADC is in a runaway state and further configured to drive an auxiliary DAC to bring the error signal into a predetermined range.

Abstract: A notch filter in a sigma-delta modulator loop filter increases SNR by limiting in-band quantization noise around a frequency to which the notch filter is precisely tuned. A tuning mode controller isolates the notch filter from other loop filter stages. A bias voltage is applied to the notch filter, causing it to resonate. Tuning mode switches insert the notch filter into a frequency-locked loop (“FLL”) circuit as a variable frequency oscillator component of the FLL. An ADC operational mode input signal is applied to the FLL as a reference signal. A tuning control component of the FLL adjusts a tunable feedback element in the notch filter to drive the FLL error signal to zero in order to precisely tune the notch filter to the center frequency of the ADC input signal. Tuning inputs to the tunable feedback element are then latched prior to re-inserting the notch filter into the modulator.

Abstract: A system includes a storage device containing machine instructions and a plurality of digital values of an oversampled sinuisoidal signal. The system also includes a core coupled to the storage. The core is configured to execute the machine instructions, wherein, when executed, the machine instructions cause the core to implement a sigma-delta modulator that retrieves the plurality of digital values from the storage device as input to the modulator. The sigma-delta modulator is configured compute an output bit stream. The system further includes an analog filter configured to receive the output bit stream from the core and to low-pass filter the output bit stream to produce a sinusoidal output signal.

Abstract: A phase-locked loop (PLL) includes a state machine programmed to automatically produce a set of control signals to select a charge-pump current and integrating capacitance value to automatically adjust a loop bandwidth of the PLL. A charge-pump DAC generates a charge-pump current of magnitude controlled by the state machine control signals. An integrator integrates the charge-pump output current to produce an integrated charge-pump output signal. The integrator has a plurality of capacitors switchably selected by control signals from the state machine to produce an integrating capacitance value. A voltage controlled oscillator (VCO) produces a PLL output frequency in response to the integrated charge-pump output signal.

Abstract: A direct current (“DC”) calibration reference voltage is applied at an input terminal of an N-level sigma-delta analog-to-digital converter (“ADC”). The ADC includes a current-mode DAC (“I-DAC”) operating as a feedback element. A count of logical 1s associated with each of N output levels is taken at outputs of a modulator portion of the ADC during a first mismatch measurement interval. Mismatch measurement logic subsequently transposes pairs of current sources between level selection switch matrices. Doing so causes modulator output error components resulting from mismatches between I-DAC current sources (“delta”) to appear as differential level-specific output counts. The mismatch measurement logic compares the differential counts to determine values of delta. The ADC then factors decimated modulator output counts by values of delta in order to correct for the I-DAC current source mismatch(es).

Abstract: A phase-locked loop (PLL) includes a state machine programmed to automatically produce a set of control signals to select a charge-pump current and integrating capacitance value to automatically adjust a loop bandwidth of the PLL. A charge-pump DAC generates a charge-pump current of magnitude controlled by the state machine control signals. An integrator integrates the charge-pump output current to produce an integrated charge-pump output signal. The integrator has a plurality of capacitors switchably selected by control signals from the state machine to produce an integrating capacitance value. A voltage controlled oscillator (VCO) produces a PLL output frequency in response to the integrated charge-pump output signal.

Abstract: A temperature sensor uses a semiconductor device that has a known voltage drop characteristic that is proportional to absolute temperature (PTAT). A controllable current source is coupled to the semiconductor device and is operable to sequentially inject a bias current having a value I(bias) and fixed ratio N of I(bias) into the semiconductor device. A delta sigma analog to digital converter (ADC) has an input coupled to the semiconductor device. The delta sigma ADC is configured to sample and integrate a sequence of voltages pairs produced across the semiconductor device by repeatedly injecting an ordered sequence of selected bias currents into the semiconductor device. The ordered sequence of selected bias currents comprises M repetitions of (N×I(bias); I(bias)) and one repetition of (M×I(bias); M×N×I(bias)).

Abstract: Methods and circuits for measuring the temperature of a transistor are disclosed. An embodiment of the method includes, providing a current into a circuit, wherein the circuit is connected to the transistor. A variable resistance is connected between the base and collector of the transistor. The circuit has a first mode and a second mode, wherein the current in the first mode flows into the base of the transistor and through the resistance and the current in the second mode flows into the emitter of the transistor. Voltages in both the first mode and the second mode are measured using different resistance settings. The temperature of the transistor is calculated based on the difference between the different voltages.

Abstract: A voltage reference circuit includes a bipolar transistor and a circuit configured to measure the ratio of emitter current to base current of the bipolar transistor. The output voltage of the voltage reference circuit is compensated as a function of the measured ratio.