Abstract: Disclosed is an adaptive stylus frontend to identify and update zero force offset pressure codes. The adaptive stylus frontend comprises a high gain instrumentation amplifier configured to receive the analog signal and provide the required gain to the analog signal. The adaptive stylus frontend comprises an analog-to-digital converter configured to convert the analog signal to digital codes at a predetermined sampling frequency. The stylus comprises an adaptive offset controller configured to adaptively identify, and update zero force offset pressure codes, wherein the zero force offset pressure code is the ADC output value when no external force is applied at the stylus tip. The zero force offset pressure comprises the pressure sensor offset introduced by a pressure sensor, the amplifier offset introduced by the amplifier, and the offset introduced by the analog to digital converter.

Abstract: Disclosed is an adaptive stylus receiver to adaptively determine presence of narrowband interference. The receiver comprises an analog-to-digital converter to digitize an incoming digitally modulated (DM) signal at a predetermined sampling frequency, a digital band pass filter configured to receive digitized DM signal and to generate a first set of frequencies from the digitized DM signal, and a frequency detection logic to adaptively determine presence of narrowband interference in a first set of frequencies, the frequency detection logic configured to estimate frequency components from the first set of frequencies, provide a first set of coefficients to a narrowband notch filter, binning of coefficients for frequencies below a threshold value, adaptively estimate narrowband notch filter coefficients by binning and provide estimated narrowband notch filter coefficients to the narrowband notch filter to suppress the narrow band interference from the first set of frequencies.

Abstract: Disclosed is an adaptive stylus receiver to adaptively determine presence of narrowband interference. The receiver comprises an analog-to-digital converter to digitize an incoming digitally modulated (DM) signal at a predetermined sampling frequency, a digital band pass filter configured to receive digitized DM signal and to generate a first set of frequencies from the digitized DM signal, and a frequency detection logic to adaptively determine presence of narrowband interference in a first set of frequencies, the frequency detection logic configured to estimate frequency components from the first set of frequencies, provide a first set of coefficients to a narrowband notch filter, binning of coefficients for frequencies below a threshold value, adaptively estimate narrowband notch filter coefficients by binning and provide estimated narrowband notch filter coefficients to the narrowband notch filter to suppress the narrow band interference from the first set of frequencies.

Abstract: A common source preamplifier for a MEMS capacitive sensor is disclosed. The preamplifier is a single-stage amplifier employing negative feedback. The preamplifier provides stable gain independent of temperature and at the same time provides effective buffering for a subsequent stage. Further, the preamplifier may be configured to provide different values of gain. Furthermore, the preamplifier has lower noise and consumes lesser area and lesser power than prior art.

Abstract: A common source preamplifier for a MEMS capacitive sensor is disclosed. The preamplifier is a single-stage amplifier employing negative feedback. The preamplifier provides stable gain independent of temperature and at the same time provides effective buffering for a subsequent stage. Further, the preamplifier may be configured to provide different values of gain. Furthermore, the preamplifier has lower noise and consumes lesser area and lesser power than prior art.

Abstract: A method for transitioning between Pulse Frequency Modulation (PFM) mode and Pulse Width Modulation (PWM) mode and vice versa, in a switching regulator is disclosed. In PFM mode, load current is estimated based on slope of waveform of the output voltage of the switching regulator. If the load current is greater than an upper threshold, then the switching regulator is set to PWM mode. In PWM mode, load current is estimated using duration of dead-time. If the duration of dead-time is higher than a pulse filter trip point, the switching regulator temporarily transitions to PFM mode. The load current is further estimated based on slope of the waveform of the output voltage and, if the load current is lower than a lower threshold, the switching regulator remains in PFM mode. If the load current is higher than the lower threshold, the switching regulator transitions back into PWM mode.

Abstract: A circuit for selecting a maximum supply voltage from a first voltage source and a second voltage source is disclosed. The circuit comprises a comparator for comparing the first voltage and the second voltage. Based on the comparison, a first bias signal and a second bias signal are generated for biasing the gate terminals of a first power switch and a second power switch respectively. The first power switch and the second power switch are biased such that the maximum voltage among the first voltage and the second voltage appear at an output node.

Abstract: A power-on reset (POR) circuit for generating a POR signal includes a current source to generate an input current. The input current is a supply voltage dependent current. The POR circuit includes a first diode operable to receive the input current to output a first voltage signal. The first diode is electrically connected in series with a resistor. Further, the POR circuit includes a second diode operable to receive the input current to output a second voltage signal. Further, the POR circuit includes a comparator operable to receive the first voltage signal and the second voltage signal to generate the POR signal at a predefined trip point. The predefined trip point is a point at which the first voltage signal equals the second voltage signal. Furthermore, the POR circuit includes a temperature compensation circuit to compensate for the variation of the predefined trip point.

Abstract: A circuit for reducing flicker noise includes a first current source coupled to an input current. The circuit includes current minors to generate output currents in response to the input current. The output currents include the flicker noise. In addition, the circuit includes a chopping circuit to reduce the flicker noise from each of the output currents.

Abstract: A spread-spectrum switching regulator for eliminating modulation ripple includes high gain amplifier that is responsive to reference voltage and feedback voltage of feedback loop to generate differential voltage, the feedback voltage being one of output voltage of the spread-spectrum switching regulator and a fraction of the output voltage; compensation circuit, coupled to the high gain amplifier, that maintains stability of the feedback loop to generate error level voltage in response to differential voltage; ramp generator that generates ramp waveform with slope adaptable to switching frequency to maintain duty cycle at constant value; pulse width modulator, coupled to compensation circuit and ramp generator, that compares error level voltage and ramp waveform to generate pulsed waveform; driver circuit, coupled to pulse width modulator, that drives the pulsed waveform to alternately switch a pair of transistors; and LC network, coupled to the pair of transistors, to average pulsed waveform to the output vo