Noise Generator

021 TEST & MEASUREMENT N4). The output of the sampler is in accordance with the potential The noise generator presented here provides constant noise energy over its bandwidth, resulting from the non-lin- ear behaviour of its switching components, more particu- larly T4. It is very useful for measurements where limited noise bands are required. Varying the ratio R6:R7 and the clock frequency enables the generated noise to be adapt- ed to specific requirements. Transistors T2 and T3 are current sources. The current through T2 is about ten times the level of that through T3. Assuming that T4 is on and that the clock input is low, T1 is off and C2 discharges. The capacitor is pulled to about half the supply voltage by the two current sources. When that state is reached, stability ensues because the potential then present at the gate of T4 keeps the FET switched on. When the clock goes high, Tl is switched on so that C2 is connected between the gate of T4 and earth. Since C2 is only pa...