Low noise mixer circuit with improved gain
First Claim
1. A mixer circuit comprising:
- a gain stage coupled to receive a first signal on a first input and a modulated bias current on a common node, and in accordance therewith, produce an output signal, the gain stage having a first current;
a current shunt circuit coupled between the common node and a reference voltage, the current shunt circuit having a second current, wherein the first current and the second current are coupled to the common node; and
a bias circuit to generate the modulated bias current, the bias circuit having an input coupled to receive a second signal, and in accordance therewith, generate the modulated bias current, and an output coupled to the common node to provide the modulated bias current to the gain stage.
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Abstract
A mixer circuit of the present invention includes a gain stage configured to receive a first signal and a modulated bias current, and in accordance therewith, produce an output signal, the gain stage generating a first current and receiving the modulated bias current from a bias circuit on a common node. The bias circuit includes an input configured to receive a second signal, and in accordance therewith, generate the modulated bias current. The mixer circuit also includes a current shunt circuit for generating a second current. The first current, the second current, and the modulated bias current are coupled to the common node. In one embodiment, the first signal is approximately a square wave, and the frequency of the first signal is one-third the frequency of the second signal.
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Citations
38 Claims
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1. A mixer circuit comprising:
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a gain stage coupled to receive a first signal on a first input and a modulated bias current on a common node, and in accordance therewith, produce an output signal, the gain stage having a first current;
a current shunt circuit coupled between the common node and a reference voltage, the current shunt circuit having a second current, wherein the first current and the second current are coupled to the common node; and
a bias circuit to generate the modulated bias current, the bias circuit having an input coupled to receive a second signal, and in accordance therewith, generate the modulated bias current, and an output coupled to the common node to provide the modulated bias current to the gain stage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 28, 29, 30, 31, 32)
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19. A receiver circuit comprising:
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an input amplifier coupled to receive an input radio frequency (RF) signal; and
a mixer circuit having a first input coupled to an output of the input amplifier and a second input coupled to receive a differential oscillating signal, the mixer circuit comprising;
a gain stage configured to receive a first signal and a modulated bias current, and in accordance therewith, produce an output signal, the gain stage generating a first current and receiving the modulated bias current on a common node;
a current shunt circuit coupled between the common node and a reference voltage, the current shunt circuit configured to generate a second current, wherein the first current and the second current are coupled to the common node; and
a bias circuit to generate the modulated bias current, the bias circuit having an input configured to receive a second signal, and in accordance therewith, generate the modulated bias current, and an output coupled to the common node to provide the modulated bias current to the gain stage.
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27. A method of mixing signals in a mixer circuit comprising:
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generating a first current in a differential stage;
generating a second current in a shunt circuit;
coupling the first current and the second current through a common node to generate a bias current in a bias circuit;
receiving an RF signal in the bias circuit;
receiving a second signal in the differential stage; and
generating a mixer output in accordance with the RF signal and the second signal.
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33. A method of mixing signals in a mixer comprising:
- biasing a gain stage of the mixer using a first current having a first magnitude at a first frequency of operation; and
biasing the gain stage of the mixer using a second current having a second magnitude at a second frequency of operation. - View Dependent Claims (34, 35, 36, 37, 38)
- biasing a gain stage of the mixer using a first current having a first magnitude at a first frequency of operation; and
Specification