Customizable tunable filters are provided herein. In certain implementations, a tunable filter including: a first filter bank including a plurality of high-pass filters each having a different cutoff frequency, and a second filter bank including a plurality of low-pass filters each having a different cutoff frequency. The tunable filter further includes a first pair of switches configured to select a first filter chosen from the first filter bank, and a second pair of switches configured to select a second filter chosen from the second filter bank. The tunable filter operates with a first cutoff frequency of the first filter and with a second cutoff frequency of the second filter.

A reconfigurable microacoustic filter is specified which comprises a ladder-type-like filter topology and a suitably placed adjustable capacitive element.

A multi-tune filter system and a control system for operating the multi-tune filter system are described herein. The multi-tune filter system is a tunable frequency range filter. Further, the multi-tune filter system is a digitally programmable filter with an adjustable passband between first and second customizable frequency bounds f1, f2.

An active current source load of a fully differential amplifier which is converted into a transconductance (g.sub.m) component also at higher frequency by feed-forwarding input signals to their gates. With signal coupling to gate, unity gain bandwidth (UGB) of the amplifier increases by a factor of two. In addition to this, the signal is coupled to source as well to achieve three-fold UGB enhancement. Thus, the effective trans-conductance is g.sub.mp at dc and becomes g.sub.mp+(g.sub.mn.sub.gate+g.sub.mn.sub.src) at high frequency which triples the UGB when g.sub.mp=g.sub.mn.sub.gate/src.

A method and apparatus for modifying or controlling a resonator connected to a signal loop having an input (18828), an output (18822), and a closed loop frequency response. The signal loop has a primary resonator (18810) having a primary frequency response. There is at least one adjustable resonator (18812) having an adjustable frequency (f) and a secondary Q-factor. An adjustable scaling block (18824) applies a gain factor (g). A controller is connected to the at least one adjustable resonator (18812) and the adjustable scaling block (18824). The controller has instructions to adjust the closed loop frequency response toward a desired closed loop frequency response by controlling the adjustable frequency (f) of the at least one adjustable resonator (18812) and the gain factor (g) of the adjustable scaling block (18824).

A variable filter and method of switching a resonant frequency of the variable filter from an initial frequency to a desired frequency, where the variable filter has a tunable frequency and a variable Q. With the variable filter operating at the initial frequency and an initial Q, the variable filter is Q-spoiled toward a low-Q state. The variable filter is tuned toward the desired frequency and the tunable resonator is Q-enhanced from the low-Q state to achieve a desired filter response.

An active current source load of a fully differential amplifier which is converted into a transconductance (g.sub.m) component also at higher frequency by feed-forwarding input signals to their gates. With signal coupling to gate, unity gain bandwidth (UGB) of the amplifier increases by a factor of two. In addition to this, the signal is coupled to source as well to achieve three-fold UGB enhancement. Thus, the effective trans-conductance is g.sub.mp at dc and becomes g.sub.mp+(g.sub.mn.sub.gate+g.sub.mn.sub.src) at high frequency which triples the UGB when g.sub.mp=g.sub.mn.sub.gate/src.

According to one embodiment, in a biquad filter, an output terminal of a first integrator is connected to an input terminal in a negative pole side of a second integrator, an output terminal of the first integrator is connected to a first input terminal in a negative pole side of an adder through the inversion amplifier, an output terminal of the second integrator is connected to a second input terminal in the negative pole side of the adder, an input terminal to which an input signal is input is connected to a third input terminal in the negative side of the adder, and an output terminal of the adder is connected to an input terminal in a negative pole side of the first integrator.

Customizable tunable filters are provided herein. In certain implementations, a tunable filter including: a first filter bank including a plurality of high-pass filters each having a different cutoff frequency, and a second filter bank including a plurality of low-pass filters each having a different cutoff frequency. The tunable filter further includes a first pair of switches configured to select a first filter chosen from the first filter bank, and a second pair of switches configured to select a second filter chosen from the second filter bank. The tunable filter operates with a first cutoff frequency of the first filter and with a second cutoff frequency of the second filter.

A tunable filter is described where the frequency response as well as bandwidth and transmission loss characteristics can be dynamically altered, providing improved performance for transceiver front-end tuning applications. The rate of roll-off of the frequency response can be adjusted to improve performance when used in duplexer applications. The tunable filter topology is applicable for both transmit and receive circuits. A method is described where the filter characteristics are adjusted to account for and compensate for the frequency response of the antenna used in a communication system.