Telefonaktiebolaget Lm Ericsson (publ)

Kirill Kozmin

Stefan Mikael Andersson

Fredrik Tillman

Ufuk Özdemir

Peter Caputa

Stefan Andersson

A filter circuitry () using an active inductor is disclosed. The filter circuitry () has a first terminal (In/Out) and a second terminal (In/Out). The filter circuitry () comprises a first transistor (M) and a second transistor (M). The filter circuitry () further comprises a first switch (S), a second switch (S), a first capacitor (C), a second capacitor (C) and a resistor (R). The first and second transistors (M/M) together with the resistor (R) and the first and second switches (S/S) are connected in a current mirror topology. The first and second capacitors (C/C) are connected at the first and second terminals of the filter circuitry () respectively. The filter circuitry () is configurable to either have the first terminal (In/Out) as input and the second terminal (In/Out) as output or have the first terminal (In/Out) as output and the second terminal (In/Out) as input by changing on-off states of the first and second switches. The transistors are interconnected in a current-mirror fashion. Depending on the switch position one of the transistors also acts as part of an active inductor such that the circuit functions as a low pass filter with a complex pole pair and a real pole. Depending on the switch position the LPF allows signal flow in either direction. For use in a TDD environment in combination with a passive mixer ().

Filter circuitry using active inductor

A technique of suppressing noise in a transmitter device () is provided, wherein the transmitter device () comprises a baseband signal processing stage () operating at baseband frequency and comprising a modulator () for converting a baseband signal into an RF signal, and an RF signal processing stage () operating at RF and comprising an amplifier (). A method implementation of this technique comprises the steps performed in a feedback loop () coupled around the amplifier () of tapping the RF signal processing stage downstream of the amplifier () to obtain an amplified RF signal comprising a baseband signal component and a noise component, downconverting the tapped RF signal to baseband frequency, removing the baseband signal component from the downconverted signal, upconverting the resulting signals still comprising the noise component to RF frequency and feeding the upconverted signal back to the RF signal processing stage upstream of the amplifier () thereby suppressing the noise component.

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Lund, Sweden

Kirill Kozmin