IP2 calibration measurement and signal generation
First Claim
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1. A radio frequency receiver on an integrated circuit (RFIC), the RFIC comprising:
- a local oscillator configured to provide a local oscillatory signal;
a mixer;
a low noise amplifier (LNA);
a resonant circuit;
an amplitude modulator;
wherein when the RFIC is configured in a first mode,
1) the LNA amplifies received RF signals which are then passed to the resonant circuit,
2) then the resonant circuit bandpass filters the amplified received RF signals which are then passed to the mixer, and wherein when the RFIC is configured in a second mode, the resonant circuit and the LNA generate an oscillatory signal and the amplitude modulator [generate and pass] modulates the oscillatory signal to provide predetermined amplitude modulated (AM) RF signals to the mixer, the mixer coupled to the amplitude modulator and to the local oscillator for downconverting the predetermined AM RF signals to produce intermediate frequency (IF) signals having frequencies within an IF passband; and
a calibration circuit coupled to the mixer, the calibration circuit configured to receive the IF signal from the mixer when the RFIC is in the second mode, to detect second order modulation (IM2) products in the IF signal, to generate a bias signal, to apply the bias signal to the mixer and to adjust the bias signal in a sense determined by the detected IM2 products to reduce the IM2 products.
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Abstract
A radio frequency receiver on an integrated circuit (RFIC) includes an oscillator circuit, which generates a radio frequency (RF) oscillatory signal having a predetermined frequency that is outside of an intermediate frequency passband of the RFIC. An amplitude modulator modulates the RF oscillatory signal to produce an amplitude modulated signal which is applied to a mixer that downconverts the amplitude modulated signal. A calibration circuit receives the downconverted signal, including second order modulation (IM2) products, and, responsive to the IM2 products, generates a bias signal that is applied to the mixer to reduce the IM2 products.
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Citations
27 Claims
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1. A radio frequency receiver on an integrated circuit (RFIC), the RFIC comprising:
- a local oscillator configured to provide a local oscillatory signal;
a mixer;
a low noise amplifier (LNA);
a resonant circuit;
an amplitude modulator;
wherein when the RFIC is configured in a first mode,
1) the LNA amplifies received RF signals which are then passed to the resonant circuit,
2) then the resonant circuit bandpass filters the amplified received RF signals which are then passed to the mixer, and wherein when the RFIC is configured in a second mode, the resonant circuit and the LNA generate an oscillatory signal and the amplitude modulator [generate and pass] modulates the oscillatory signal to provide predetermined amplitude modulated (AM) RF signals to the mixer, the mixer coupled to the amplitude modulator and to the local oscillator for downconverting the predetermined AM RF signals to produce intermediate frequency (IF) signals having frequencies within an IF passband; and
a calibration circuit coupled to the mixer, the calibration circuit configured to receive the IF signal from the mixer when the RFIC is in the second mode, to detect second order modulation (IM2) products in the IF signal, to generate a bias signal, to apply the bias signal to the mixer and to adjust the bias signal in a sense determined by the detected IM2 products to reduce the IM2 products. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- a local oscillator configured to provide a local oscillatory signal;
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12. A method for calibrating a radio frequency receiver on an integrated circuit (RFIC) for second order modulation (IM2) products, the method comprising:
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configuring the RFIC in a first mode to
1) amplify a received RF signal using a low noise amplifier (LNA), and then
2) bandpass filter the amplified received RF signal using a resonant circuit;configuring the RFIC in a second mode to generate a radio frequency (RF) oscillatory signal using the resonant circuit, the RF oscillatory signal having a frequency that is outside of an intermediate frequency (IF) passband of the RFIC in response to receiving instructions to switch between filtering the received RF signal and generating the RF oscillatory signal; modulating the RF oscillatory signal with a periodic modulating signal to provide an amplitude modulated signal; mixing the amplitude modulated signal with a local oscillator (LO) signal in a mixer to generate a downconverted signal including a second order modulation (IM2) products; detecting the IM2 products and adjusting a bias voltage applied to the mixer in a sense determined by the detected IM2 products to reduce the detected IM2 products. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. An second order modulation (IM2) calibrator in a radio frequency receiver on a integrated circuit (RFIC) having a mixer, the IM2 calibrator comprising:
- a low noise amplifier (LNA);
a resonant circuit;
an amplitude modulator;
wherein in a first mode,
1) the LNA amplifies received RF signals which are then passed to the resonant circuit, and then
2) the resonant circuit bandpass filters the amplified received RF signals, and wherein in a second mode, the LNA and the resonant circuit generate an oscillatory signal and the amplitude modulator modulates the oscillatory signal to generate an amplitude modulated RF oscillatory signal having a predetermined frequency that is outside of an intermediate frequency (IF) passband of the RFIC, the generated RF signal causing the mixer to produce an output signal that is within the IF passband and that includes IM2 products; and
an IM2 calibration circuit, coupled to the mixer, the IM2 calibration circuit including;
an IM2 detector configured to receive the output signal and to detect the IM2 products in the output signal, and an IM2 compensation adjustor configured to generate a bias voltage applied to the mixer, based on the detected IM2 products. - View Dependent Claims (21, 22, 23, 24, 25)
- a low noise amplifier (LNA);
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26. A second order modulation (IM2) calibrator in a radio frequency receiver on a integrated circuit (RFIC) having a mixer, the IM2 calibrator comprising:
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a signal generator, coupled to the mixer, configured to switch between filtering a received RF signal and generating an amplitude modulated RF oscillatory signal having a predetermined frequency that is outside of an intermediate frequency (IF) passband of the RFIC, the generated RF signal causing the mixer to produce an output signal that is within the IF passband and that includes IM2 products; and an IM2 calibration circuit, coupled to the mixer, the IM2 calibration circuit including; an IM2 detector configured to receive the output signal and to detect the IM2 products in the output signal, the IM2 detector including an accumulator for accumulating the IM2 products to the exclusion of other direct current (DC) components over a plurality of clock pulses, and a register for storing a single bit value associated with the accumulated IM2 products for each of the clock pulses; and an IM2 compensation adjustor configured to generate a bias voltage applied to the mixer, based on the detected IM2 products. - View Dependent Claims (27)
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Specification