Circuit for detecting a magnitude and phase of an impedance of a load
First Claim
1. Circuit for detecting a magnitude and a phase of an impedance of a load, the load being connectable to a radio frequency (RF) amplifier by means of a feed line, the circuit comprising:
- a) first means for sensing a peak value of an output voltage of the RF amplifier, the first means being connected by a node to the feed line;
b) second means for sensing a peak value of an output current of the RF amplifier, the second means comprising a peak sensor element placed in the feed line and being circuited in series between the RF amplifier and the load, wherein the peak sensor element is a resistor, a capacitor or a coil; and
c) third means forc1) measuring a signal whose value depends on the phase between output voltage and output current, orc2) deriving the phase between output voltage and output current using linear multiplication;
d) whereby the first means and/or the second means for peak value sensing comprise, in a branch coupled to the feed line,d1) a mixer and an amplitude limiter ord2) a peak diode detector;
e) wherein an energy flow from the RF amplifier to the load through the feed line is used for detecting the impedance and phase.
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Accused Products
Abstract
The invention relates to an antenna which is coupled to an RF amplifier. Environmental conditions change the impedance of the antenna, which reduces output power, efficiency and linearity. A circuit is provided which is designed to detect the impedance of the antenna. With the measured impedance, impedance matching can be accomplished. The circuit for detecting the impedance detects the signal travelling from the RF amplifier to the antenna, and measures the peak voltage and the peak current of this signal. Furthermore, the phase difference between the voltage and the current is measured. The advantage of the circuit is its compactness allowing for an easy integration on a chip. Furthermore, an impedance matching circuit is suggested which makes use of the above circuit for detecting the impedance.
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Citations
19 Claims
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1. Circuit for detecting a magnitude and a phase of an impedance of a load, the load being connectable to a radio frequency (RF) amplifier by means of a feed line, the circuit comprising:
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a) first means for sensing a peak value of an output voltage of the RF amplifier, the first means being connected by a node to the feed line; b) second means for sensing a peak value of an output current of the RF amplifier, the second means comprising a peak sensor element placed in the feed line and being circuited in series between the RF amplifier and the load, wherein the peak sensor element is a resistor, a capacitor or a coil; and c) third means for c1) measuring a signal whose value depends on the phase between output voltage and output current, or c2) deriving the phase between output voltage and output current using linear multiplication; d) whereby the first means and/or the second means for peak value sensing comprise, in a branch coupled to the feed line, d1) a mixer and an amplitude limiter or d2) a peak diode detector; e) wherein an energy flow from the RF amplifier to the load through the feed line is used for detecting the impedance and phase. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Impedance matching circuit for matching the impedance of a load to the impedance of a RF amplifier, whereby the load is connectable to the RF amplifier by means of a feed line, the impedance matching circuit comprising:
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an adaptive output network connected in between the RF amplifier and the load, an impedance detector coupled to a node of the feed line, wherein an energy flow from the RF amplifier to the load through the feed line is used for detecting the impedance and phase of the load, and a control unit to adjust the adaptive matching circuit in response to a measured impedance, wherein the impedance detector comprises; a) first means for sensing a peak value of an output voltage of the RF amplifier, the first means being connected by the node, b) second means for sensing a peak value of an output current of the RF amplifier, the second means comprising a peak sensor element placed in the feed line and being circuited in series between the RF amplifier and the load, wherein the peak sensor element is one of a resistor, a capacitor, and a coil, and c) third means for c1) measuring a signal whose value depends on the phase between output voltage and output current, or c2) deriving the phase between output voltage and output current by means of linear multiplication d) whereby the first means and/or the second means comprise, in a branch coupled to the feed line, d1) a mixer and an amplitude limiter or d2) a peak diode detector. - View Dependent Claims (10, 11)
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12. A circuit comprising:
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a voltage sensor configured to sense a peak value of an output voltage of a radio frequency (RF) amplifier, the RF amplifier being connectable to a load by a feed line, the voltage sensor being connected by a node to the feed line; a current sensor configured to sense a peak value of an output current of the RF amplifier, the current sensor comprising a peak sensor element placed in the feed line in series between the RF amplifier and the load, wherein the peak sensor element is a resistor, a capacitor, or a coil, wherein the voltage sensor and/or the current sensor comprise, in a branch coupled to the feed line, a mixer and an amplitude limiter or a peak diode detector; and a circuit element configured to measure a signal whose value depends on a phase between output voltage and output current, or configured to derive the phase between output voltage and output current by linear multiplication, wherein an energy flow from the RF amplifier to the load through the feed line is used for detecting an impedance and phase of the load. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification