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US 7,071,760 B2Granted
Filter circuit and detection circuit having filter circuit
AssigneeOki Electric Industry Co., Ltd.
InventorAkira Yoshida
Life of this patent
Estimating the term…
Abstract
A filter circuit has an input terminal which is input with a first current, and which is coupled with a first node, capacitor, of which one terminal is coupled with the first node, of which the other terminal is coupled with a second node, and which integrates the first current and outputs voltage, a transconductance means, of which one terminal is coupled with the first node, of which another terminal is coupled with the second node, of which the other terminal is coupled with a third node, and which outputs a second current being proportional to the voltage to the third node and an output terminal which is coupled with the first node, and which outputs the voltage.
Claims25
A detecting circuit comprising:
- a double balanced mixer having a first output and a second output, the double balanced mixer providing a first output current at the first output and a second output current at the second output;
- a first filter circuit connected to the first output of the double balanced mixer, the first filter circuit including a capacitor and a transconductance circuit;
- and
- a second filter circuit connected to the second output of the double balanced mixer, the second filter circuit receives the second output current from the double balanced mixer,
- the double balanced mixer having
- a first transistor which applies a first current to a first node according to a first signal,
- a second transistor which applies a second current to the first transistor according to a second signal,
- a third transistor which applies a third current to the first transistor according to a third signal, and
- a first current mirror circuit which applies a first voltage to the first output according to a fourth current which is supplied to the second transistor,
- the transconductance circuit having
- a first power node connected to have a first electrical potential applied thereto,
- a second power node connected to have a second electric potential applied thereto,
- an input node,
- a first current source connected to the first power node,
- a second current source connected to the first power node,
- a third current source connected to the second power node,
- a first voltage supply circuit connected to the second power node,
- a fourth transistor having a control electrode connected to the input node,
- a first electrode connected to the first current source and a second electrode connected to the third current source, and
- a fifth transistor having a control electrode connected to the first voltage supply circuit, a first electrode connected to the second current source and a second electrode connected to the third current source.
17 more elements
A detection circuit comprising:
- a double balanced mixer circuit having a first input terminal, a second input terminal, a first output terminal and a second output terminal;
- a second filter circuit connected to the second output terminal of the double balanced mixer circuit;
- and
- a first filter circuit connected to the first output terminal of the double balanced mixer circuit, the first filter circuit including
- a first input terminal connected to the first output terminal of the double balanced mixer circuit and to a first node,
- a first output terminal connected to the first node,
- a first capacitor having a first terminal connected to the first node and a second terminal connected to a second node, and
- a first transconductance circuit having a first terminal connected to the first node, a second terminal connected to the second node and a third terminal connected to a third node, the first transconductance circuit outputting a first current proportional to a voltage at the third node,
- the first transconductance circuit having
- a first current source connected to the first node,
- a second current source,
- a third current source connected to the second node,
- a first transistor having a control electrode connected to the third node, a first electrode connected to the first current source and a second electrode connected to the third current source, and
- a second transistor having a control electrode connected to a first voltage supply circuit, a first electrode connected to the second current source and a second electrode connected to the third current source, the first voltage supply circuit supplying a first control voltage for the control electrode of the second transistor and being connected to the second node.
11 more elements
A detection circuit comprising:
- a first filter circuit having an input terminal and an output terminal connected to the input terminal thereof, the first filter circuit including a first capacitor and a first transconductance circuit;
- a second filter circuit having an input terminal and an output terminal connected to the input terminal thereof;
- and
- a double balanced mixer circuit having a first input terminal, a second input terminal, a first output terminal connected to the input terminal of the first filter circuit, and a second output terminal connected to the input terminal of the second filter circuit, the double balanced mixer circuit including
- a current source connected to a first power supply,
- a first switch circuit connected to the current source and the first input terminal of the double balanced mixer circuit, the first switch circuit operating in response to a signal input to the first input terminal of the double balanced mixer circuit,
- a second switch circuit connected to the first switch circuit and the second input terminal of the double balanced mixer circuit, the second switch circuit operating in response to a signal input to the second input terminal of the double balanced mixer circuit,
- a first current mirror circuit connected to a second power supply, the second switch circuit and the first output terminal of the double balanced mixer circuit, and
- a second current mirror circuit connected to the second power supply, the second switch circuit and the second output terminal of the double balanced mixer circuit,
- the first filter circuit including
- a first input terminal connected to the first output terminal of the double balanced mixer circuit and to a first node;
- a first output terminal connected to the first node;
- the first capacitor having a first terminal connected to the first node and a second terminal connected to a second node;
- and
- the first transconductance circuit having a first terminal connected to the first node, a second terminal connected to the second node and a third terminal connected to a third node, the first transconductance circuit outputting a first current proportional to a voltage at the third node, wherein the first transconductance circuit having
- a first current source connected to the first node,
- a second current source,
- a third current source connected to the second node,
- a first transistor having a control electrode connected to the third node, a
- first electrode connected to the first current source and a second electrode connected to the third current source, and
- a second transistor having a control electrode connected to a first voltage supply circuit, a first electrode connected to the second current source and a second electrode connected to the third current source, the first voltage supply circuit supplying a first control voltage for the control electrode of the second transistor and being connected to the second node.
18 more elements
Dependencies are inferred from the claim text.