Low-voltage low-power high-linearity active CMOS mixer
First Claim
1. A high linearity, low power, low voltage active mixer for RF applications, comprising:
- an RF transconductance amplifier to transform the input voltage to current, the transconductance amplifier having a constant transconductance over a wide range of input differential voltages;
a mixing stage to down-convert the RF current to the desired IF;
an ac-coupling stage between the RF transconductance amplifier and the mixing stage; and
an IF stage that converts an information bearing signal back to voltage.
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Abstract
A low voltage, low power, high linearity active CMOS mixer for radio frequency (RF) wireless communication applications consists of high linearity RF transconductor to convert the incoming RF voltage into a RF current; an ac-coupling stage to deliver the RF current to the next stage, and to block the DC signal and the flicker noise of the RF transconductor; followed by a current commutating (mixing) stage to down-convert the RF signal to the desired intermediate frequency (IF), and an IF section that converts the down-converted signal current back to voltage. The invention suggests a novel low-voltage, low-power RF mixer circuit that exhibits a high linearity in terms of IIP2 and IIP3 and is suitable for a low voltage, direct conversion receiver (DCR) which requires a relatively high IIP2. The DCR is a candidate for the fourth generation of mobile communication systems (4G).
33 Citations
16 Claims
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1. A high linearity, low power, low voltage active mixer for RF applications, comprising:
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an RF transconductance amplifier to transform the input voltage to current, the transconductance amplifier having a constant transconductance over a wide range of input differential voltages;
a mixing stage to down-convert the RF current to the desired IF;
an ac-coupling stage between the RF transconductance amplifier and the mixing stage; and
an IF stage that converts an information bearing signal back to voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An RF transconductance amplifier for use in a high linearity, low power, low voltage active mixer, the RF transconductance amplifier comprising;
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a floating voltage source;
a capacitive feed-forward path; and
a p-channel and an n-channel single transistor transconductors. - View Dependent Claims (13, 14, 15)
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16. A method of improving the linearity of a current commutating active mixer comprising:
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transforming the input voltage to current with a transconductance amplifier, the transconductance amplifier having transconductors with constant transconductance over a wide range of differential input voltages;
down-converting the RF current to the desired IF with a mixing stage;
ac-coupling the RF transconductance amplifier and the mixing stage; and
converting an information bearing signal back to voltage using an IF stage.
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Specification