Linear sweep-voltage generators and precision amplitude comparator using transistors

Design requirements for transistor bootstrap and Miller integrator circuits are discussed and typical circuits illustrated. To achieve 0.1% linearity a special compensating network is necessary for the bootstrap circuit. Miller integrator linearity is better than this using three grounded emitter stages with a bandwidth of 100 kc/s, resulting in good stability with high gain. Practical details are given for a comparator circuit in which a diode bridge feedback circuit switches feedback polarity rapidly, as the two inputs reach coincidence. The bridge is capacity coupled to a blocking oscillator so that accuracy of comparison depends on the gain of the active device, and is insensitive to operating point. Diodes need careful selection to obtain a matched pair. A brief discussion of optimum values for components is given together with some data on temperature effects.