Method to improve I/Q-amplitude balance and receiver quadrature channel performance
First Claim
1. A radio receiver comprising:
- an in-phase channel and a quadrature channel, said channels being provided in parallel at a respective input with quadrature modulated radio frequency signals;
a first mixer arranged in said in-phase channel, said first mixer comprising a switching/multiplying stage for downconverting a radio frequency signal fed to said in-phase channel to an in-phase component of said radio frequency signal;
a second mixer arranged in said quadrature channel, said second mixer comprising a switching/multiplying stage for downconverting a radio frequency signal fed to said quadrature channel to a quadrature component of said radio frequency signal;
amplifying means arranged in at least one of said in-phase channel and said quadrature channel for amplifying signals in the analog domain with an adjustable gain;
detecting means for detecting an imbalance in gain between at least part of said in-phase channel, said part including said first mixer, and of a corresponding part of said quadrature channel, said corresponding part including said second mixer; and
controlling means for controlling the gain of said amplifying means in a way that detected imbalances in gain are reduced.
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Accused Products
Abstract
The invention relates to a quadrature demodulating radio receiver and to a method for reducing an imbalance in gain between an in-phase channel and a quadrature channel of such a radio receiver. Received radio frequency signals are downconverted to in-phase and quadrature-phase signals, either to a baseband or a certain IF frequency. In order to improve the performance of the channels, it is proposed that imbalances in gain or amplitude between the two channels are compensated in the analog domain. This is achieved by employing in at least one of the channels amplifying means with an adjustable gain for amplifying received signals in the analog domain, the adjustable gain being controlled according to a detected imbalance in gain. The invention moreover relates to an equivalently designed radio transmitter and a corresponding method. The invention equally relates to components and communications systems including such a radio receiver or transmitter, and to a transconductance mixer for such a radio receiver or transmitter.
67 Citations
44 Claims
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1. A radio receiver comprising:
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an in-phase channel and a quadrature channel, said channels being provided in parallel at a respective input with quadrature modulated radio frequency signals;
a first mixer arranged in said in-phase channel, said first mixer comprising a switching/multiplying stage for downconverting a radio frequency signal fed to said in-phase channel to an in-phase component of said radio frequency signal;
a second mixer arranged in said quadrature channel, said second mixer comprising a switching/multiplying stage for downconverting a radio frequency signal fed to said quadrature channel to a quadrature component of said radio frequency signal;
amplifying means arranged in at least one of said in-phase channel and said quadrature channel for amplifying signals in the analog domain with an adjustable gain;
detecting means for detecting an imbalance in gain between at least part of said in-phase channel, said part including said first mixer, and of a corresponding part of said quadrature channel, said corresponding part including said second mixer; and
controlling means for controlling the gain of said amplifying means in a way that detected imbalances in gain are reduced. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 24, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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18. A method for reducing an imbalance in gain between an in-phase channel and a quadrature channel of a quadrature demodulating radio receiver, the method comprising:
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feeding quadrature modulated radio frequency signals in parallel to said in-phase channel and to said quadrature channel of said radio receiver;
downconverting said radio frequency signals to an in-phase component of said radio frequency signal in the in-phase channel and to a quadrature component of said radio frequency signal in the quadrature channel;
amplifying signals in at least one of said in-phase and said quadrature channels in the analog domain with an adjustable gain before or after downconversion;
determining whether there exists an imbalance in gain between at least a part of said in-phase channel and a corresponding part of said quadrature channel, which parts respectively include the downconversion of radio frequency signals; and
controlling the adjustable gain with which signals are amplified in at least one of said in-phase and said quadrature channels in a way that a detected imbalance in gain is reduced.
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25. A radio transmitter comprising:
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an in-phase channel to an input of which in-phase components of a signal are fed;
a quadrature channel to an input of which quadrature-phase components of said signal are fed;
a first mixer arranged in said in-phase channel, said first mixer comprising a switching/multiplying stage for upconverting received in-phase components of signals to a radio frequency signal;
a second mixer arranged in said quadrature channel, said second mixer comprising a switching/multiplying stage for upconverting received quadrature-phase components of signals to a radio frequency signal;
amplifying means arranged in at least one of said in-phase channel and said quadrature channel for amplifying signals in the analog domain with an adjustable gain;
detecting means for detecting an imbalance in gain between at least part of said in-phase channel, said part including said first mixer, and of a corresponding part of said quadrature channel, said corresponding part including said second mixer; and
controlling means for controlling the gain of said amplifying means in a way that detected imbalances in gain are reduced.
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40. A method for reducing an imbalance in gain between an in-phase channel and a quadrature channel of a quadrature modulating radio transmitter, the method comprising:
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feeding an in-phase component of a signal to said in-phase channel and a quadrature-phase component of said signal to said quadrature channel of said radio transmitter;
upconverting the in-phase component of said signal to a radio frequency signal in said in-phase channel, and upconverting the quadrature component of said signal to a radio frequency signal in said quadrature channel;
amplifying signals in at least one of said in-phase and said quadrature channels in the analog domain with an adjustable gain before or after upconversion;
determining whether there exists an imbalance in gain between at least a part of said in-phase channel and a corresponding part of said quadrature channel, which parts respectively include the upconversion of radio frequency signals; and
controlling the adjustable gain with which signals are amplified in at least one of said in-phase and said quadrature channels in a way that a detected imbalance in gain is reduced. - View Dependent Claims (41, 42, 43, 44)
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Specification