Transceivers
AssigneeLime Microsystems Limited
InventorsSrdjan Milenkovic, Danny Webster, Ebrahim Bushehri, Ri{hacek over (s)}ard Kurylo
Life of this patent
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Abstract
An RF transceiver apparatus comprises transmitter circuitry arranged to convert signals from a baseband frequency to RF transmission frequencies and receiver circuitry arranged to convert signals from RF reception frequencies to the baseband frequency. The transmitter and receiver circuitry each comprise three mixers arranged to convert a signals between the baseband frequency, a first intermediate frequency; a second intermediate frequency that is higher than the transmission frequencies; and a second intermediate frequency to the transmission frequency.
Claims18
An RF transceiver apparatus comprising transmitter circuitry arranged to convert signals from a baseband frequency to a range of RF transmission frequencies and receiver circuitry arranged to convert signals from a range of RF reception frequencies to the baseband frequency wherein:
- the transmitter circuitry comprises a first transmitter mixer arranged to convert a signal from the baseband frequency to a first intermediate frequency;
- a second transmitter mixer arranged to convert the signal from the first intermediate frequency to a second intermediate frequency that is higher than the transmission frequencies;
- and
- a third transmitter mixer arranged to convert the signal from the second intermediate frequency to the transmission frequency;
- and
- the receiver circuitry comprises a third receiver mixer arranged to convert the RF input from the reception frequency to the second intermediate frequency which is higher than the reception frequency,
- a second receiver mixer arranged to convert the signal from the second intermediate frequency to a first intermediate frequency which is lower than the reception frequency, and
- a first receiver mixer arranged to convert the signal from the first intermediate frequency to the baseband frequency;
- and
- the second receiver mixer and the second transmitter mixer are both driven by a common second stage fixed frequency synthesizer.
A direct digital frequency synthesizer comprising a look up table expressing at least one of a sine function and a cosine function in terms of Walsh function coefficients.
A delta sigma modulator apparatus for modulating a digital signal, the modulator comprising a quantizer and a plurality of loop filters, wherein the loop filters form a first feedback loop arranged to generate at least one first difference signal representing the difference between the input and output of the quantizer, and modify the at least one difference signal by a first coefficient factor to provide a first feedback signal, and a second feedback loop arranged to generate at least one second difference signal representing the difference between the input to the modulator and the output of the quantizer and modify the at least one second difference signal by a second coefficient factor to provide a second feedback signal, wherein a series of delay lines is provided between the input to the modulator and the input to the quantizer, and a plurality of first feedback loops are arranged to feed back the first difference signal to a plurality of feedback points separated by the delay lines, the apparatus further comprising a plurality of second feedback loops arranged to feed back the second difference signal to a plurality of feedback points separated by the delay lines, wherein each of the second feedback loops includes delay means arranged to compensate for delay in the delay lines.
A delta sigma modulator apparatus for modulating a digital signal, the modulator comprising:
- a quantizer;
- a plurality of loop filters;
- a plurality of feedback input points between the input to the modulator and the input to the quantizer, a set of first feedback sub-sections each associated with one of the feedback points and arranged to:
- generate a first difference signal from the difference between the output of the quantizer and the output from its respective feedback input point,
- modify the first difference signal, and
- input the first difference signal at the respective feedback input point;
- and
- a second set of second feedback sub-sections each associated with one of the feedback points and arranged to:
- generate a second difference signal from the difference between the output of the quantizer and the input from its respective feedback input point,
- modify the second difference signal, and
- input the second difference signal at the respective feedback input point.
A delta sigma modulator apparatus for modulating a digital signal, the modulator comprising:
- a quantizer;
- a plurality of loop filters;
- a plurality of feedback input points between the input to the modulator and the input to the quantizer,
- a set of first feedback sub-sections each associated with one of the feedback points and each comprising:
- a first feedback part arranged to generate a difference signal from the difference between the output of the quantizer and the output from the its respective feedback input point, modify the difference signal, and feed it back to the respective feedback input point;
- and
- a second feedback part arranged to generate a difference signal from the difference between the output of the quantizer and the input from its respective feedback input point, modify the difference signal, and feed it back to the respective feedback input point.
A delta sigma modulator apparatus for modulating a digital signal, the modulator comprising:
- a quantizer;
- a plurality of loop filters, wherein the loop filters are arranged to provide a noise transfer function of the form
- N
-
- (
- z
- )
- =
- 1
- -
- A
-
- (
- z
- )
- 1
- +
- B
-
- (
- z
- )
- .
A delta sigma modulator apparatus for modulating a digital signal, the modulator comprising:
- a quantizer;
- a plurality of loop filters, and arranged to utilize a noise transfer function of the general form:
- N(z)=(1+2z−2+z−4)·(1+1.75−2+z−4).
An apparatus providing frequency shifted single ended output from transformerless differential input, the apparatus comprising three doubly balanced frequency mixers connected through in phase isolating combiner splitters, wherein two of the mixers are arranged to mix in phase and quadrature analogue inputs with in phase and quadrature inputs from an oscillator and output differential in phase and quadrature output signals, wherein there are two in phase isolating combiner splitters arranged to receive as inputs the differential phase and quadrature output signals and generate differential filtered signals, and wherein a third one of the mixers is arranged to mix the differential filtered signals with differential inputs from an oscillator and generate a frequency shifted output signal.
Dependencies are inferred from the claim text.