Q-controlled microresonators and tunable electronic filters using such resonators

DETAILED DESCRIPTION The present invention is directed to a resonator structure.
The resonator structure comprises a first electrode at which an input signal may be applied and a second electrode at which an output signal may be sensed.
The resonator structure further includes a feedback means for applying the output signal to the first electrode for controlling the Q of the resonator structure.
The equivalent circuit series resistance (R.
sub.
X) of the resonator of the present invention is proportional to the inverse of the Q of the resonator.
As such, the controlled value of Q is independent of the original Q of the resonator.
Rather, it is dependent only on the control voltage (V.
sub.
Q) or some other controlling factor such as resistance values.
Additionally, the gain of the resonator (v.
sub.
0 /v.
sub.
i) is equal to the number of input fingers divided by the number of feedback fingers.
This is advantageous in that it offers very precise gain values.
This enables construction of bandpass biquads with precisely settable gains.
Also, the gain will stay constant as the Q is changed.
Dimensions of a microresonator of the present invention may be: a length between about 5 microns (.
mu.
m) and 1000 .
mu.
m, a width between about 5 .
mu.
m and 100 .
mu.
m, and a thickness from between about 0.
1 and 100 .
mu.
m.
High-Q tunable electronic filters based upon the Q-controlled microresonators of the present invention are suitable for batch fabrication using standard complementary metal-oxide semiconductor (CMOS) integrated circuit and micromachining technologies.
The Q-controlled microresonators may serve as adjustable biquad stages in various filter architectures such as coupled (or cascaded) biquad, follow-the-leader feedback (FLF), or other multiple-loop feedback techniques.
Frequency and bandwidth are independently voltage-controllable.
This permits adaptive signal processing.
Noise analysis determines that the dynamic range of a proposed high-Q filter is much higher than that of its high-Q active RC counterparts, i