A Passive Integrator With Bandwidth Over Gigahertz

We describe the performance of a passive integrator that mainly consists of a resistor R and a capacitor C in series, and a 50-
$\Omega $
matching resistor. A circuit model of the passive integrator taking into account the parasitic parameters of each component in the passive integrator is proposed. The circuit simulation results indicate that the performance of the passive integrator is not sensitive to the stray inductance of resistor R but its parasitic capacitance influences the upper limited response frequency of the passive integrator remarkably. Due to self-resonance, the upper limited response frequency of the passive integrator is decreased with respect to increasing the stray inductance of capacitor C. However, this effect could be compensated somewhat by a resistor in series with this capacitor. It is also suggested that the performance of the passive integrator is degraded with increasing the stray inductance of the matching resistor and the bandwidth of the passive integrator could be expanded with proper stray capacitance in parallel with this matching resistor. We have designed a passive integrator of a time constant of about
$2.2~\mu $
s with a 2-k
$\Omega $
glass-glaze resistor in series with a 1.1-nF annular capacitor and a 50-
$\Omega $
matching resistor. The bandwidth of this passive integrator is measured by a vector network analyzer (VNA) with a high-frequency probe. Its upper limited response frequency is about 1.25 GHz.