Abstract: A system for filtering a signal includes a plurality of filter modules coupled in series. Each filter module includes a filter and a variable gain element. Each filter is capable of. receiving an input signal, attenuating a portion of the input signal that is outside a passband associated with the filter, and outputting at least a portion of the input signal that is within the passband associated with the filter. Each variable gain element is capable of receiving a control signal and inducing a gain in an output of the filter based on the control signal.

Abstract: A device for measuring voltage levels includes a root mean square (RMS) detector. The RMS detector includes a linear multiplier, a log converter, a low-pass filter and a temperature compensator. The linear multiplier multiplies a voltage of an input signal by the voltage of the input signal. The low-pass filter couples to an output of the linear multiplier. The log converter generates a logarithmic signal having a voltage that is logarithmically related to a voltage of an output of the low-pass filter. The temperature compensator adjusts the logarithmic signal based on a temperature of the RMS detector. The RMS detector is capable of determine an RMS voltage level of the input signal.

Abstract: A filter circuit includes a polyphase filter coupled to a first circuit component and a second circuit component. The first circuit component propagates four input current signals to the polyphase filter. The third and fourth input current signals are substantially one-hundred-eighty degrees out of phase with the first and second input current signals. The polyphase filter receives the input current signals and generates four output current signals that are out of phase with each other. The second circuit component generates first and second output signals using the four output current signals. The first and second output signals are ninety degrees out of phase with each other.

Abstract: A filter circuit includes a polyphase filter coupled to a first circuit component and a second circuit component. The first circuit component propagates four input current signals to the polyphase filter. The third and fourth input current signals are substantially one-hundred-eighty degrees out of phase with the first and second input current signals. The polyphase filter receives the input current signals and generates four output current signals that are out of phase with each other. The second circuit component generates first and second output signals using the four output current signals. The first and second output signals are ninety degrees out of phase with each other.