HP HP-Bench-Briefs-1985-03-05 free download

File name HP-Bench-Briefs-1985-03-05.pdf

EWLETT 4CKARD E / 4 ~ ~ E J ~ A F U R M A FROM HEWLET-PAGKARD .i I ,ro 4 - T ~ O N MARCH/MAY 1985 .- When a n analog signal, either a dc voltage to be measured has an ac voltage or a current, has to be component, such as ripple from a expressed i n digital form, t h e power supply. As shown in Figure 2, conversion is very often first done coincidence of t h e input voltage by transforming the analog signal value and staircase ramp will not into an analog time interval. The always happen at the same level for analog time interval, in turn, can be each measurement. A difference easily measured with a clock. The between two measurements can be time displayed by the clock, when as high as the peak-to-peak value of the clock period is correctly chosen, t h e ripple voltage. A possible J is also a digital expression of the improvement would be to connect a analog value. Another way to do an low-pass filter in the signal input. analog-to-digital conversion (A/D However, s u c h a f i l t e r would conversion) is to increment or Figure 1. Simple staircase A/D converter. considerably reduce the speed at decrement a digitally controlled and gives a start signal that causes a which measurements can be made. known analog signal and to compare staircase ramp generator to begin to \c I ' it with t h e analog signal to be generate a 1 millivolt step with each Successive Approximation A/D digitized. At coincidence of both clock pulse. Assume that the input Converter s