US 2003/0148751 A1Published application

Differential mixer injection with optional step gain control

AssigneeRF Micro Devices, Inc.

InventorsKelvin Kai Tuan Yan, Kihong Kim, Luke Joseph

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Abstract

A differential RF input signal drives the plus and minus terminals of a center tapped primary winding, which couples the differential RF input signal to the plus and minus terminals of a center tapped secondary winding. From the secondary winding, the coupled, differential RF signal drives a double-balanced mixer core operating in response to a differential local oscillator signal. The output of the mixer core is a differential IF signal representative of the differential RF input signal down-converted at the local oscillator frequency. A step reduction in gain associated with the RF input signal may be implemented using bypass circuitry coupled across the primary of the transformer, wherein a relatively small resistance or impedance is coupled across the primary to effectively reduce the load of the differential amplifiers driving the primary.

Claims29

Dependent claims

A receiver front end comprising:

a) a transformer comprising a primary formed from series connected first and second primary windings and a secondary formed from series connected first and second secondary windings, the primary having a center tap at a junction of the first and second primary windings for receiving a bias signal and the secondary having a center tap at a junction of the first and second secondary windings for sinking current;
b) a differential radio frequency (RF) input having a first node operatively coupled to the first primary winding and a second node operatively coupled to the second primary winding;
and
c) differential mixing circuitry comprising:
i) a differential input having a first node coupled to the first secondary winding and a second node coupled to the second secondary winding;
ii) a differential local oscillator (LO) input;
and
iii) a differential intermediate frequency (IF) output,
wherein a differential RF signal applied to the first and second primary windings is coupled to the differential input of the differential mixing circuitry via the first and second secondary windings and mixed with a differential local oscillator signal to provide a differential IF signal at the differential IF output.

6 more elements

A receiver front end comprising:

a) a transformer comprising a primary having a first end, a center tap, and a second end forming series connected first and second primary windings and a secondary having a first end, a center tap, and a second end forming series connected first and second secondary windings;
b) a differential radio frequency (RF) input having a first node operatively coupled to the first end of the primary and a second node operatively coupled to the second end of the primary;
and
c) differential mixing circuitry comprising:
i) first, second, third, and fourth transistors wherein outputs of the first and second transistors are operatively coupled to the first end of the secondary and outputs of the third and fourth transistors are operatively coupled to the second end of the secondary;
ii) a differential local oscillator (LO) input having a first node operatively coupled to bias control inputs of the first and fourth transistors and a second node operatively coupled to bias control inputs of the second and third transistors;
and
iii) a differential intermediate frequency (IF) output having a first node operatively coupled to the outputs of the first and third transistors and a second node coupled to the outputs of the second and fourth transistors;
wherein a differential RF signal having a first component applied to the first end of the primary and a second component applied to the second end of the primary is coupled to the differential input of the differential mixing circuitry via the first and second secondary windings and mixed with a differential local oscillator signal to provide a differential IF signal at the differential IF output.

6 more elements

A receiver front end comprising:

a) first and second transformers each comprising a primary having a first end, a center tap, and a second end forming series connected first and second primary windings and a secondary having a first end, a center tap, and a second end forming series connected first and second secondary windings;
the first ends, second ends, and center taps of the primaries for the first and second transformers being respectively coupled to one another;
b) a differential radio frequency (RF) input having a first node operatively coupled to the first ends of the primaries and a second node operatively coupled to the second ends of the primaries;
c) in-phase differential mixing circuitry comprising:
i) first, second, third, and fourth transistors wherein outputs of the first and second transistors are operatively coupled to the first end of the secondary of the first transformer and the outputs of the third and fourth transistors are operatively coupled to the second end of the secondary of the first transformer;
ii) an in-phase differential local oscillator (LO) input having a first node operatively coupled to bias control inputs of the first and fourth transistors and a second node operatively coupled to bias control inputs of the second and third transistors;
and
iii) an in-phase differential intermediate frequency (IF) output having a first node operatively coupled to the outputs of the first and third transistors and a second node coupled to the outputs of the second and fourth transistors;
and
d) quadrature differential mixing circuitry comprising:
i) fifth, sixth, seventh, and eighth transistors wherein outputs of the fifth and sixth transistors are operatively coupled to the first end of the secondary of the second transformer and outputs of the seventh and eighth transistors are operatively coupled to the second end of the secondary of the second transformer;
ii) a quadrature differential local oscillator (LO) input having a first node operatively coupled to bias control inputs of the fifth and eighth transistors and a second node operatively coupled to bias control inputs of the sixth and seventh transistors;
and
iii) a quadrature intermediate frequency (IF) output having a first node operatively coupled to the output of the fifth and seventh transistors and a second node coupled to the outputs of the sixth and eighth transistors.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/072,374Filed 7 Feb 2002
Published: 7 Aug 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

H04B 1/28
For superheterodyne receivers: the receiver comprising at least one semiconductor device having three or more electrodes
H03D 7/145
With transistors: using a combination of bipolar transistors and field-effect transistors
H03D 7/1458
With transistors: double balanced arrangements, i.e. where both input signals are differential
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