Enhanced operational amplifier trim circuitry and techniques are presented herein. In one implementation, a circuit includes a reference circuit configured to produce a set of reference voltages, and a digital-to-analog conversion (DAC) circuit. The DAC circuit comprises a plurality of transistor pairs, where each pair among the plurality of transistor pairs is configured to provide portions of adjustment currents for an operational amplifier based at least on the set of reference voltages and sizing among transistors of each pair. The circuit also includes drain switching elements coupled to drain terminals of the transistors of each pair and configured to selectively couple one or more of the portions of the adjustment currents to the operational amplifier in accordance with digital trim codes.

Digital-to-Analog (DAC) circuitry for an implantable pulse generator is disclosed which is used to program currents at the electrodes. Calibration circuitry allows the positive and negative currents produced at each electrode to be independently calibrated to achieve an ideal (linear) response across a range of amplitude values provided to the DAC circuitry by a digital amplitude bus. The calibration circuitry includes electrode gain and electrode offset circuitry for each of the electrodes. Current range DAC circuitry is also provided which can be used to adjust the gain and offset current at all of the electrodes. The current range DAC circuitry is particularly useful when spanning a range of therapeutic currents for a patient, and allows all possible amplitude values provided by the digital bus to be used to span the range. This can improve (reduce) the current resolution of the electrode currents with each amplitude value step.

An analog-to-digital converter (ADC) system includes a main ADC, a reference ADC, a sampling control circuit, and a calibration circuit. The main ADC obtains a first sampled input voltage by sampling an analog input according to a first sampling clock, and performs analog-to-digital conversion upon the first sampled voltage to generate a first sample value. The reference ADC obtains a second sampled voltage by sampling the analog input according to a second sampling clock, and performs analog-to-digital conversion upon the second sampled voltage to generate a second sample value. The sampling control circuit controls the second sampling clock to ensure that the second sampling clock and the first sampling clock have a same frequency but different phases, and adjusts the second sample value to generate a reference sample value. The calibration circuit applies calibration to the main ADC according to the first sample value and the reference sample value.

An integrated circuit that includes a generating circuit is described. During operation, the generating circuit may provide an edge clock having a target phase within a clock period of an input clock, where the generating circuit does not include a delay-locked loop (DLL). For example, the generating circuit may include a gated ring oscillator that provides a reference clock having a first fundamental frequency that is larger than a second fundamental frequency of the input clock. Note that the gated ring oscillator may be programmable to adjust the first fundamental frequency within a predefined range of values. Moreover, the generating circuit may include a control circuit that determines a reference count of a number of edges of the reference clock within a reference period of the reference clock.

A capacitor circuit includes: a capacitor array including a plurality of capacitors; a switch array including a plurality of switch circuits, the switch circuits being respectively connected to the capacitors of the capacitor array; a plurality of switch control signal lines supplied with a plurality of switch control signals; and a substrate having a major surface on which the switch circuits are formed. At least part of the capacitors of the capacitor array is formed of a first conductive layer. The switch control signal lines are formed of a second conductive layer provided between the major surface and the first conductive layer. The capacitor array and the switch array are disposed so as to overlap each other at least in part in a plan view when viewed in a normal direction of the major surface.

A system and method where a comparator is operatively coupled to an output of a Digital-to-analog Converter (DAC). The DAC may comprise a single DAC core or a plurality of interleaved DAC cores. The comparator is configured to capture properties of DAC core output. A digital engine is operatively coupled to receive output of the comparator and configured to calculate a cross-correlation between comparator output and input to the DAC core(s). The digital engine may be configured to determine if the skew of each DAC core is positive or negative and to determine if a skew correction term for the DAC core(s) should be decreased or increased, based on the skew of each DAC core being positive or negative, respectively. In interleaved DAC core devices, clock frequency sampling edges of the comparator may alternate between clock edges of each of the interleaved DAC cores.

A method and apparatus for use in a digitally tuning a capacitor in an integrated circuit device is described. A Digitally Tuned Capacitor DTC is described which facilitates digitally controlling capacitance applied between a first and second terminal. In some embodiments, the first terminal comprises an RF+ terminal and the second terminal comprises an RF− terminal. In accordance with some embodiments, the DTCs comprise a plurality of sub-circuits ordered in significance from least significant bit (LSB) to most significant bit (MSB) sub-circuits, wherein the plurality of significant bit sub-circuits are coupled together in parallel, and wherein each sub-circuit has a first node coupled to the first RF terminal, and a second node coupled to the second RF terminal. The DTCs further include an input means for receiving a digital control word, wherein the digital control word comprises bits that are similarly ordered in significance from an LSB to an MSB.

Devices and methods for improving voltage handling and/or bi-directionality of stacks of elements when connected between terminals are described. Such devices and method include use of symmetrical compensation capacitances, symmetrical series capacitors, or symmetrical sizing of the elements of the stack.

A calibration method for a digital-to-analog converter (DAC) is disclosed. The DAC is applied to a successive approximation analog-to-digital converter (SA ADC) and includes a first capacitor, multiple second capacitors and a bridge capacitor. The method includes the steps of: (a) controlling voltages at two input terminals of a comparator of the SA ADC to be equal; (b) changing a voltage at a first terminal of the first capacitor; (b) obtaining a first output of the SA ADC; (d) after obtaining the first output, controlling voltages at the two input terminals of the comparator to be equal; (e) changing voltages at multiple first terminals of the second capacitors; (f) obtaining a second output of the SA ADC; and (g) calibrating the DAC according to the first output and the second output.

A digital to analog conversion, DAC, device for converting digital signals to analog signals comprises a RF output for outputting the analog signals, a thermometer segment comprising a first number of data slices and a second number calibration slices, and a calibration controller, which electrically disconnects one of the data slices from the RF output and at the same time connects one of the calibration slices to the RF output as replacement slice for the respective data slice and performs a calibration of the disconnected data slice.