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US 11,528,011 B2Granted
Method for tunably multiplying an impedance
AssigneeKing Fahd University of Petroleum and Minerals
InventorsMunir Al-Absi, Muhammad T. Abuelma'atti
Life of this patent
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Abstract
A tunable impedance multiplier with high multiplication factor is described. A single externally connected resistor is used and the multiplier is free of passive elements. The circuit can realize a positive or a negative impedance multiplier. Applications of the design to low and high pass filters are also presented. The simulation and experimental results show that the new design enjoys a multiplication factor above 400 at 2 Hz-to 7 MHz.
Claims5
A method for tunably multiplying an impedance, comprising:
- connecting an alternating current source, ix, to a first current input of a current feedback operational amplifier, CFOA;
- connecting a second current input of the CFOA to an impedance, Z, wherein Z is a resistor or a capacitor having an equivalent input impedance Zin;
- connecting a first output of the CFOA to an inverting input of a first operational transconductance amplifier, OTA1 having a specified gain, gm;
- connecting a second output of the CFOA to a grounded resistance, Ro;
- connecting a non-inverting input of the OTA1 to ground;
- connecting a current output, Io, of the OTA1 to the first current input of the CFOA;
- sweeping the amplitude of a first bias current source, iB1, connected to a bias input of the OTA1 over a range of frequencies of alternating current ix;
- determining the −3 dB points of the current output corresponding to the range of frequencies;
- and
- calculating the equivalent input impedance based on the equation
- Z
-
- in
- =
- Z
- 20
- ×
- IB
-
- 1
- ×
- R
-
- 0
- wherein gm=20×IB1.
22 more elements
A method for tunably multiplying an impedance, comprising:
- connecting an alternating current source, ix, to a first current input of a current feedback operational amplifier, CFOA;
- connecting a second current input of the CFOA to an impedance, Z;
- connecting a first output of the CFOA to an inverting input of a first operational transconductance amplifier, OTA1 having a specified gain, gm;
- connecting a non-inverting input of the OTA1 to ground;
- connecting a current output of the OTA1 to the first current input of the CFOA;
- connecting an inverting input of a second operational transconductance amplifier OTA2 to a second voltage output of the CFOA, connecting the non-inverting input of the OTA2 to ground and connecting the output of the OTA2 to the inverting input of the OTA2;
- connecting a second bias current source, iB2, to a bias input of the OTA2,
- sweeping the amplitudes of the first bias current source, of the OTA1 and second bias current source, iB2, of the OTA2 over a range of frequencies of alternating current ix,
- determining the −3 dB points of the current output corresponding to the range of frequencies;
- and
- calculating the multiplication of the impedance, Z, based on the
- equation
-
- multiplication
- =
- Z
-
- IB
-
- 2
- IB
-
- 1
- .
21 more elements
Dependencies are inferred from the claim text.