CMOS current mode RF detector and method
First Claim
1. An integrated detector circuit, comprising:
- a first gain stage having an input that monitors a high frequency signal for routing a first detection current to a node and having a first current source coupled to form a first bias current having a first maximum value wherein a maximum value of the first detection current is limited to the first maximum value; and
a second gain stage including a second current source for supplying a second bias current having a second maximum value indicative of a predefined amplitude of the high frequency signal, and having an input for monitoring the high frequency signal to route a portion of the second bias current to the node as a second detection current, wherein the second detection current is limited to the second maximum value when the high frequency signal is greater than the predefined amplitude, and wherein the second maximum value is greater than the first maximum value.
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Abstract
An integrated detector circuit (20) includes first and second gain stages (GS1, GS2). The first gain stage has an input (82) that monitors a high frequency signal (VRFDET) for routing a first detection current (IS1) to a node (60). The second gain stage includes a first current source (PF1) that supplies a bias current (IMAX1) indicative of a predefined amplitude of the high frequency signal. An input of the second gain stage monitors the high frequency signal to route a portion of the bias current to the node as a second detection current (IS2), which is limited to the bias current when the high frequency signal is greater than the predefined amplitude to compensate for a nonlinearity in a transconductance of the second gain stage.
53 Citations
20 Claims
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1. An integrated detector circuit, comprising:
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a first gain stage having an input that monitors a high frequency signal for routing a first detection current to a node and having a first current source coupled to form a first bias current having a first maximum value wherein a maximum value of the first detection current is limited to the first maximum value; and
a second gain stage including a second current source for supplying a second bias current having a second maximum value indicative of a predefined amplitude of the high frequency signal, and having an input for monitoring the high frequency signal to route a portion of the second bias current to the node as a second detection current, wherein the second detection current is limited to the second maximum value when the high frequency signal is greater than the predefined amplitude, and wherein the second maximum value is greater than the first maximum value.
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2. An integrated detector circuit, comprising:
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a first gain stage having an input that monitors a high frequency signal for routing a first detection current to a node; and
a second gain stage including a first current source for supplying a bias current indicative of a predefined amplitude of the high frequency signal, and having an input for monitoring the high frequency signal to route a portion of the bias current to the node as a second detection current, wherein the second detection current is limited to the bias current when the high frequency signal is greater than the predefined amplitude wherein the second gain stage includes a first transistor having a control electrode coupled for receiving the high frequency signal and a first conduction electrode coupled to the node for supplying the second detection current. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9)
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10. A detector circuit, comprising gain stages wherein each gain stage includes a current source for establishing maximum current levels in the gain stages at corresponding amplitudes of a high frequency signal and wherein each gain stage has a different maximum current level, wherein the gain stages function with transfer functions that convert the high frequency signal to detection currents for summing at a common node to produce an output detection signal as a substantially linear function of the high frequency signal, wherein the detection currents reach the maximum current levels at the corresponding amplitudes to compensate for nonlinearities in the transfer functions.
- 11. A detector circuit, comprising gain stages that include current sources for establishing maximum current levels in the gain stages at corresponding amplitudes of a high frequency signal, wherein the gain stages function with transfer functions that convert the high frequency signal to detection currents for summing at a common node to produce an output detection signal as a substantially linear function of the high frequency signal, wherein the detection currents reach the maximum current levels at the corresponding amplitudes to compensate for nonlinearities in the transfer functions and wherein the gain stages include transistors whose control electrodes are coupled to an input of the detector circuit and whose sources are coupled to the common node for providing the detection currents.
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13. A method of detecting a high frequency signal, comprising the steps of:
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amplifying a high frequency signal with a first transconductance to produce a first detection current;
amplifying the high frequency signal with a second transconductance to produce a second detection current for summing with the first detection current to produce an output signal; and
limiting the first detection current to a constant value to compensate for a nonlinearity in the second transconductance when the high frequency signal is greater than a predefined amplitude. - View Dependent Claims (14, 15, 16, 17)
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18. A detector circuit, comprising:
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a current source for providing a bias current;
a first transistor operating in response to a high frequency signal and having a first width and a first conduction electrode coupled to a node for producing a portion of the bias current as a first detection current; and
a second transistor operating in response to the high frequency signal, having a second width less than the first width, and having a first conduction electrode coupled to the node for producing a second detection current for summing with the first detection current to produce an output signal. - View Dependent Claims (19, 20)
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Specification