Non-quadrature local oscillator mixing and multi-decade coverage
AssigneeAnalog Devices International Unlimited Company
InventorNiall Kevin Kearney
Life of this patent
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Abstract
Aspects of this disclosure relate to a very low intermediate frequency (VLIF) receiver with multi-decade contiguous radio frequency (RF) band coverage. Non-quadrature local oscillator (LO) signals drive mixers. The non-quadrature signals can be generated from low noise digital dividers having non-traditional division ratios. The non-traditional division ratios can be prime number ratios such as 5 and 7. The systematic non-quadrature nature of the LO/mixer can be subsequently corrected by a deterministic I-Q coupling network prior to complex signal processing.
Claims17
A wireless device having nonquadrature local oscillator mixing and continuous bandwidth coverage, the wireless device comprising:
- a local oscillator circuit including a voltage controlled oscillator circuit and a divider circuit in communication with an output of the voltage controller oscillator circuit, the divider circuit being selectable between an integer division factors in a range from 4 to 7, the local oscillator configured to generate first and second carrier signals;
- first and second mixer circuits configured to mix a radio frequency signal with the first and second carrier signals to generate first and second mixed signals, respectively;
- and
- an image correction circuit including first and second static offset circuits that are configured to apply a correction factor to the first and second mixed signals to correct static offset errors in response to the divider circuit being configured with the integer division factor in the range being an odd number;
- wherein each of the first and second static offset circuits are selectable between a first configuration that is selected in response to the divider circuit being configured as a divide-by-5 divider, a second configuration that is selected in response to the divider circuit being configured as a divide-by-7 divider, and a third configuration that is selected in response to the divider circuit being configured as one of a divide-by-4 divider and a divide-by-6 divider.
A method to provide a wireless device with continuous bandwidth coverage, the method comprising:
- selecting an integer division factor in a range from 4 to 7 in a divider circuit of a local oscillator circuit;
- generating first and second local oscillator carrier signals with the local oscillator circuit;
- mixing, with a mixer circuit, the first and second local oscillator carrier signals with a radio frequency signal to generate I and Q signals;
- correcting an image attenuation of the I and Q signals by applying the I and Q signals to an image correction circuit that includes first and second static offset circuits that are each selectable;
- and
- selecting configurations of the first and second static offset circuits between a first configuration in response to the divider circuit being configured as a divide-by-5 divider, a second configuration that is selected in response to the divider circuit being configured as a divide-by-7 divider, and a third configuration that is selected in response to the divider circuit being configured as one of a divide-by-4 divider and a divide-by-6 divider.
A wireless device having nonquadrature local oscillator mixing and continuous bandwidth coverage, the wireless device comprising:
- a local oscillator circuit including a voltage controlled oscillator circuit and a divider circuit in communication with an output of the voltage controller oscillator circuit, the divider circuit being selectable between integer division factors in a range from 4 to 7, the local oscillator configured to generate first and second carrier signals;
- first and second mixer circuits configured to mix a radio frequency signal with the first and second carrier signals to generate I and Q signals, respectively;
- and
- an image correction circuit comprising a first selectable static offset correction circuit configured to apply a first static correction factor to the Q signal and a second selectable static offset correction circuit configured to apply a second static correction factor to the I signal, the image correction circuit further comprising a first residual offset correction circuit configured to apply a first residual correction factor to the Q signal and a second residual offset correction circuit configured to apply a second residual correction factor to the I signal in response to the divider circuit comprising one of a divide-by-5 divider and a divide-by-7 divider.
Dependencies are inferred from the claim text.