Demodulation of an IF-signal by a sigma-delta converter

Claim 2

An electronic receive arrangement according to claim 1 wherein the time discrete sampling structure comprises a switching member under the control of a square wave signal.

Claim 3

An electronic receive arrangement according to claim 2 wherein the frequency of the square wave signal is the carrier signal frequency or a subharmonic of the carrier signal frequency.

Claim 4

An electronic receive arrangement according to claim 2 wherein the frequency of the square wave frequency is selected so that the frequency of the down converted signal is intermediate the carrier frequency and the frequency of the baseband signal.

Claim 5

An electronic receive arrangement according to any preceding claim wherein the time discrete sampling means comprises switched capacitor switching elements.

Claim 6

An electronic receive arrangement for receiving a modulated carrier signal, the arrangement comprising a sigma-delta signal converter, a mixer/demodulator controlled on the carrier frequency or its subharmonic frequency or on a frequency at least close to these, and at least one adder included in a closed signal loop, characterized in that the received, modulated carrier signal (in) is first directed to the input stage (10) of the sigma-delta signal converter which is implemented as a time discrete sampling structure, the first member (1) of which serves as the mixer, that the output of the mixer is directed to the first second input of said adder (3) and that the second input (f1) of the adder (3) is the feedback signal (out) of the sigma-delta signal converter, whereby the output signal (out) is directed into a base-frequency output signal through a decimator and low-pass filtering.

Claim 7

A receive arrangement according to claim 6, characterized in that the mixing member (1) is essentially a switching member which is directed by a square wave signal on the carrier frequency (LO) or on its subharmonic (LO/n) frequency, whereby the signal (in) applied to the input is folded on the base frequency.

Claim 8

A receive arrangement according to claim 6 or 7, characterized in that the mixing frequency (LO) is replaced by frequency LO + Δf, whereby the signal (in) applied to the input is folded on a nearly base-frequency intermediate frequency Δf.

Claim 9

A receive arrangement according to claims 6, 7 or 8, characterized in that said input stage (10) is implemented using components of a switched capacitor integrator.

Claim 10

A receive arrangement according to any preceding claim characterized in that the sigma-delta converter comprises at least one adjustable amplification step for automatic gain control (AGC).

Claim 11

An IQ-mixer/demodulator in which the input signal is divided into two branches I (in phase) and Q (quadrature), respectively, characterized in that the receive arrangement according to any of the preceding claims is used in both branches.

Claim 12

A receive arrangement according to claim 11, characterized in that the required phasing arrangement is either made for the input signal (in), the local one (LO), or for both of them.

Claim 13

The utilization of the receive arrangement according to any of the preceding claims in a radio telephone.