US 6,714,263 B2Granted

Multiple conversion tuner

AssigneeZarlink Semiconductor Inc.

InventorNicholas Paul Cowley

Life of this patent

Estimating the term…

Loading patent…

Abstract

A multiple conversion tuner comprises a plurality of cascade-connected frequency changers, each of which comprises a mixer and a local oscillator. The tuner also comprises a local oscillator frequency selecting circuit which controls the frequencies of the local oscillators. The frequencies are controlled so that the final mixer converts a desired signal to the final intermediate frequency and so that the frequency band occupied by the desired signal at the output of each mixer is within the passband of the following intermediate frequency part of the tuner. The local oscillator frequencies are also chosen so that there is no signal at a frequency Fi in the input spectrum to the ith mixer such that: IF i - Bw i 2 ≤ [LeftBracketingBar] F i ± F s [RightBracketingBar] ≤ IF i + Bw i 2 where IF1 is the ith intermediate frequency to which the desired signal is converted, Bwi is the bandwidth of the desired signal at the output of the ith frequency changer and Fs is the frequency of any component signal which may be generated by non-linear mixing of any combination of the signals from the local oscillators.

Claims10

Dependent claims

A multiple conversion tuner, comprising:

N cascade-connected frequency changers, each having an output, where N is an integer greater than one and each ith one of said frequency changers comprises a mixer and a local oscillator, where 0<i≦N;
N intermediate frequency parts each having a passband;
and a local oscillator frequency selecting circuit for selecting frequencies of oscillation of at least two of said local oscillators so that:
(i) a desired signal is converted to an Nth intermediate frequency at said output of an Nth of said frequency changers;
(ii) a frequency band occupied by said desired signal at said output of each jth one of said frequency changers is within said passband of each jth one of said intermediate frequency parts of said tuner;
and
(iii) there is no signal at a frequency Fi in an input spectrum of said mixer of each ith one of said frequency changers such that:
IF i - Bw i 2 ≤ [LeftBracketingBar] F i ± F s [RightBracketingBar] ≤ IF i + Bw i 2
where IFi is an ith intermediate frequency to which said desired signal is converted, Bwi is a bandwidth of said desired signal at said output of each ith one of said frequency changers and Fs is a frequency of any component signal which is generatable by non-linear mixing of any combination of output signals of said local oscillators of said N frequency changers.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/934,610Filed 22 Aug 2001
Priority: GB 002052822 Aug 2000
Published: US 2002/0122140 A15 Sep 2002
Granted: 30 Mar 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H03D 7/161
Multiple-frequency-changing: all the frequency changers being connected in cascade
H03D 7/165
Multiple-frequency-changing: at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature
H04B 1/28
For superheterodyne receivers: the receiver comprising at least one semiconductor device having three or more electrodes
H03D
Demodulation or transference of modulation from one carrier to another