Title :
Potential instability in a transistor current source
Abstract :
A high-frequency bipolar transistor, often used as a switched current source in sampling and in current-steering circuits, is potentially a Colpitts oscillator. This consideration is generally overlooked. The key to instability is the driving point admittance. Provided that the load resistance is lower than that which meets a derived criterion, free oscillators will take place at a frequency of a resonant tank circuit. The solution based on analysis, simply requires that a resistor be added in series with the load in order that the criterion for unconditional stability shall be met.
Keywords :
Bipolar transistors; Circuit oscillations; Equivalent circuits; Oscillators; Stability; bipolar transistors; circuit oscillations; equivalent circuits; oscillators; stability; Admittance; Bipolar transistors; Circuit stability; Oscillators; RLC circuits; Resistors; Resonance; Resonant frequency; Sampling methods; Switching circuits;
Journal_Title :
Solid-State Circuits, IEEE Journal of
DOI :
10.1109/JSSC.1975.1050659
