Impedance adjusting device
View Patent ↗An impedance adjusting device includes a power output port, a ground terminal, a capacitor assembly including at least one capacitor, and a power output port. The power input port is electronically connected to a switching power supply, and the capacitor is electronically connected between the power input port and the ground terminal. The capacitor is connected in parallel to an output capacitor of the switching power supply to regulate a flat impedance of the switching power supply when an audio signal is played at full 20 Hz to 20 KHz frequencies at the same output audio voltage level.
1. An impedance adjusting device for connecting to a switching power supply including an output capacitor having a self-resonance, with the impedance adjusting device comprising:
a power input port adapted to connect to the switching power supply;
a ground terminal;
a capacitor assembly including at least one assembly capacitor having a first common terminal and a second common terminal; wherein the first common terminal is electronically connected with the power input port, and wherein the second common terminal is electronically connected with the ground terminal; and
a power output port electronically connected with the first common terminal of the at least one assembly capacitor;
wherein the at least one assembly capacitor has an impedance related with frequency of the output capacitor of the switching power supply and is adapted to be connected in parallel to the output capacitor.
2. The impedance adjusting device as claimed in claim 1 , wherein the at least one assembly capacitor comprises multiple capacitors connected in parallel; and
wherein each of the multiple capacitors has the first common terminal electronically connected with the power input port and the second common terminal electronically connected with the ground terminal.
3. The impedance adjusting device as claimed in claim 1 , further comprising an inductor electronically connected between the power input port and the power output port.
4. The impedance adjusting device as claimed in claim 1 , further comprising a diode;
wherein an anode of the diode is electronically connected with the power input port, and a cathode of the diode is electronically connected with the power output port.
5. The impedance adjusting device as claimed in claim 1 , further comprising a first resistor electronically connected between the power input port and the power output port.
6. The impedance adjusting device as claimed in claim 1 , further comprising a second resistor, a zener diode, a first transistor, and a second transistor;
wherein:
the second resistor is electronically connected between a cathode of the zener diode and the power input port;
the zener diode has an anode electronically connected with the second common terminal of the at least one assembly capacitor;
the first transistor has an emitter electronically connected with the power input port, a base electronically connected with the cathode of the zener diode, and a collector electronically connected with a base of the second transistor; and
the second transistor has an emitter electronically connected with the power input port and a collector electronically connected with the power output port.
7. The impedance adjusting device as claimed in claim 6 , wherein the first transistor and the second transistor are PNP type transistors.
8. The impedance adjusting device as claimed in claim 2 , wherein a largest capacitance of the multiple capacitors is determined by a formula according to a predetermined attenuation value (db), a predetermined smallest frequency (f s ), an impedance (R load ) of a load, an input current (I in ) of the load, and an output current (I out ) of the load,
db
=
10
×
log
(
I
out
2
×
R
load
I
in
2
×
(
R
load
+
1
2
π
f
s
c
)
)
.
9. The impedance adjusting device as claimed in claim 8 , wherein capacitances of remaining of the multiple capacitors are determined by a method that the capacitance of a next capacitor (C next ) is determined by dividing the capacitance of a previous capacitor (C previous ) by a fixed number (N),
C
next
=
C
previous
N
.
10. The impedance adjusting device as claimed in claim 8 , wherein a smallest capacitance of the multiple capacitors is determined by the formula whose predetermined smallest frequency (f s ) is replaced by a predetermined largest frequency (f l ),
db
=
10
×
log
(
I
out
2
×
R
load
I
in
2
×
(
R
load
+
1
2
π
f
l
c
)
)
.
11. The impedance adjusting device as claimed in claim 2 , further comprising an inductor electronically connected between the power input port and the power output port.
12. The impedance adjusting device as claimed in claim 2 , further comprising a diode;
wherein an anode of the diode is electronically connected with the power input port, and a cathode of the diode is electronically connected with the power output port.
13. The impedance adjusting device as claimed in claim 2 , further comprising a first resistor electronically connected between the power input port and the power output port.
14. The impedance adjusting device as claimed in claim 2 , further comprising a second resistor, a zener diode, a first transistor, and a second transistor;
wherein:
the second resistor is electronically connected between a cathode of the zener diode and the power input port;
the zener diode has an anode electronically connected with the second common terminal of the at least one assembly capacitor;
the first transistor has an emitter electronically connected with the power input port, a base electronically connected with the cathode of the zener diode, and a collector electronically connected with a base of the second transistor; and
the second transistor has an emitter electronically connected with the power input port and a collector electronically connected with the power output port.
15. The impedance adjusting device as claimed in claim 14 , wherein the first transistor and the second transistor are PNP type transistors.