Abstract: A system and method are provided for adjusting the phase output of a Hogge phase detector. The method comprises: using a Hogge phase detector, generating a reference signal; using the Hogge phase detector, generating a phase and reference signals; accepting an adjust signal; modifying the amplitude of the phase signal in response to the adjust signal; integrating the amplitude modified phase signal; using the integrated signal as a phase adjusted signal; integrating the reference signal; using the integrated reference signal and phase adjusted signal to generate a voltage controlled oscillator (VCO) signal; at the Hogge phase detector, accepting the VCO signal as the clock signal. Some aspects of the method further comprise: using the VCO signal to sample data at a settled first phase of the clock; changing the adjust signal; and, using the VCO signal to sample data at a settled second phase of the clock.

Abstract: A system and method are provided for measuring amplifier gain in a digital network. The method includes accepting a digital input signal; amplifying the input signal (Vin); comparing the amplified signal to dc thresholds; measuring output errors; and, calculating the amplifier gain in response to the thresholds. More specifically, accepting a digital input signal includes accepting an input signal having an amplitude. Comparing the amplified signal to dc thresholds includes comparing the amplified signal to a low threshold and a high threshold. Measuring errors includes measuring a predetermined error condition in response to the high threshold and the low threshold. Then, calculating the amplifier gain in response to the thresholds includes calculating the amplifier gain in response to the high threshold, the low threshold, and the input signal amplitude.

Abstract: A system and method are provided for compensating a comparator threshold level. The method comprises: accepting an input signal with an ac component; lowpass filtering the input signal to generate the input signal average voltage; accepting the input signal average voltage; accepting a first dc level; summing the average voltage with the first dc level; supplying a first sum as a first comparator threshold level; comparing the input signal to the first comparator threshold level; and, supplying a first comparator output signal with an ac component. In some aspects of the method, accepting a first dc level includes accepting a plurality of dc levels. Then, the average voltage is summed with each of the plurality of dc levels and supplied as a corresponding plurality of comparator threshold levels. The input signal is compared to each of the comparator threshold levels and a plurality of comparator output signals are supplied.

Abstract: A system and method are provided for controlling the phase of a voltage controlled oscillator output. The method comprises: accepting a plurality of VCO outputs coarsely differentiated by phase; selecting one of the VCO outputs; finely modifying the phase of the selected VCO output; and, supplying the phase modified VCO output. In one aspect, accepting VCO outputs coarsely differentiated by phase includes: accepting a first VCO output (I0); accepting a second VCO output (I1), differentiated approximately 90 degrees from the first VCO output; accepting a third VCO output (Q0), differentiated approximately 90 degrees from the second VCO output; and, accepting a fourth VCO output (Q1), differentiated approximately 90 degrees from the third VCO output. Finely modifying the phase of the selected VCO output includes modifying the selected VCO output in the range between +45 and −45 degrees. In one aspect, the output is modified in 16 discrete steps.

Abstract: A system and method are provided for reducing the threshold bias offset voltage in a comparator, by canceling and bypassing the bias offset current errors. The comparator system comprises amplification stages with bias cancellation circuitry and a threshold setting circuit. The bias offset current cancellation circuit is used to cancel the base current of differential amplifier input emitter follower. The bias offset current cancellation circuit also cancels the loading effect of amplifier input emitter-follower driving stage. The threshold offset voltage is further reduced by the threshold setting circuit. The threshold-setting circuit includes two integrators and a unit gain operation amplifier. The integrators have the input accept a single-ended input signal, an output connected to the negative input of the comparator, and an output connected to the unit gain operational amplifier, whose output is connected to the negative input of the comparator.

Abstract: A ramp circuit discharges an output capacitor to generate a substantially linear ramp signal, current injection is used to stabilize the ramp's output, reducing overshooting and ringing. With faster output stabilization, the ramp exhibits significantly faster repetition rates suitable testing high speed components such as RAM, microprocessors, high speed logic, and the like. The ramp includes an output transistor, with its output defining an output node coupled to a current source and a charge storage device such as a capacitor. The charge storage device charges when the transistor is "on". Namely, when the transistor is turned on, the output charge storage device is coupled to a reference voltage, which charges the device in a fixed time. When the transistor is turned "off", the charge storage device discharges, aided by the flow of current through the current source, resulting in the linear ramp signal.

Abstract: A timing vernier repeatedly generates a timing output signal, which includes a timing event such as a state transition, pulse, etc. Unlike prior timing verniers, the present timing event is capable of significantly faster repetition rates. After the ramp signal is initiated responsive to a trigger signal, it changes from a predetermined starting level at a predetermined substantially linear rate. A digital-to-analog converter (DAC) provides an analog timing select signal and a reset select signal responsive to a digital timing select signal. The reset select signal represents the current timing select signal offset by a predetermined amount. A comparator, coupled to the ramp and the DAC, produces the timing event when the ramp output signal reaches the analog timing select signal. Thus, greater analog timing select signals cause earlier timing events, whereas lesser timing select signals result in later timing events. The delay of the timing event is directly proportional to the analog timing select signal.

Abstract: A ramp circuit repeatedly generates a substantially linear ramp signal. Ramp switch junction capacitance that otherwise causes a nonlinear output is compensated to improve signal linearity and enable faster retriggering. The ramp includes an output transistor, with its output coupled to a current source and a charge storage device. The output charge storage device charges when the transistor is on. When the transistor is turned off, the output charge storage device discharges, resulting in the changing ramp signal. The output transistor inherently includes a junction capacitance, which causes a nonlinearity in the discharge of the charge storage device. This nonlinearity appears as a quick drop in the ramp signal relative to the slower rate of steady-state decrease. This nonlinearity is prevented, however, by compensating for the output transistor's junction capacitance.