Abstract: A sigma delta converter configured for DC offset correction is presented. The sigma delta modulator has integrator circuitry including an integrator input and an integrator output. An input signal received at the integrator input has an input AC voltage component and a DC offset component. Capacitors are connected to the integrator input, and a first set of switches is connected to the pair of capacitors. The first set of switches transfer a first charge to the pair of capacitors during a first phase, and a second set of switches transfer the first charge and a second charge to the integrator input.

Abstract: Automatic gain control is provided in a sigma-delta analog-to-digital converter. The automatic gain control is entirely or partly provided by an amplifier and an attenuator within the sigma-delta analog-to-digital converter. The amplifier within the sigma-delta time continuous loop prior to quantization and an attenuator in the feedback prior to summation with incoming signals. Scaling within the sigma-delta analog-to-digital converter results in lower current requirements for automatic gain control without disturbing or minimizing disturbance of the stability of a sigma-delta topology. By providing at least part of the automatic gain within the analog-to-digital converter, the specifications or requirements of the LNA or baseband amplifiers may be reduced or limited.

Abstract: A current-mode filter with a transfer function having complex zeros includes a voltage differentiator having first and second bipolar transistors with respective first and second inputs and outputs and being coupled in an emitter follower configuration. A floating capacitor is coupled between the first and second outputs of the voltage differentiator. The floating capacitor forms a finite zero in the transfer function of the filter. At least one current mirror, isolated from the floating capacitor, is coupled to the voltage differentiator so as to substantially cancel any signal non-linearities introduced by the emitter follower configuration.

Abstract: A current-mode filter with a transfer function having complex zeros includes a voltage differentiator having first and second bipolar transistors with respective first and second inputs and outputs and being coupled in an emitter follower configuration. A floating capacitor is coupled between the first and second outputs of the voltage differentiator. The floating capacitor forms a finite zero in the transfer function of the filter. At least one current mirror, isolated from the floating capacitor, is coupled to the voltage differentiator so as to substantially cancel any signal non-linearities introduced by the emitter follower configuration.