Current-differencing band-pass filter realization with application to high-frequency electronically tunable low-supply-voltage current-mirror-only oscillator

A new method of realizing a band-pass filter by taking the difference between the outputs of two unequal bandwidth low-pass filters is proposed. The resulting band-pass filter is particularly suitable for implementation in current-mode forms. Such a current-differencing band-pass filter will then be applied to realize a new high-frequency, low-supply-voltage, current-mirror-only oscillator, possessing wide electronically tunable frequency range. A new simple and convenient loop-gain control method using the Early effect associated with the output transistors of the current-mirrors has also been employed to control the oscillation amplitude