DC current regulator insensitive to conducted EMI
First Claim
1. A current regulator circuit comprising:
- a first circuit node (32) which is operable to receive an external input voltage;
a transistor (M1) having an input, a first leg and a second leg, the first leg of the transistor being isolated from the first circuit node (32);
an amplifier (10) having an output connected to the input of the transistor, a first amplifier input for receiving a reference voltage (VREF) and a second amplifier input connected to the first circuit node (32);
a low-pass filter (33) connected between the output of the amplifier and the first circuit node (32);
a current mirror (36) connected in series with the second leg of the transistor (M1) and having a first branch (38) for providing a regulated output current and a second branch (37) which connects to the first circuit node (32), wherein the first branch (38) is directly or indirectly coupled to an output stage (40), which comprises a further current mirror, wherein the further current mirror is an EMI-filtering current mirror.
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Accused Products
Abstract
A DC current regulator circuit comprises a first circuit node (32) which is operable to receive an external input voltage. A transistor (M1) has an input, a first leg and a second leg. The first leg of the transistor is isolated from the first circuit node (32). An amplifier (10) has an output connected to the input of the transistor (M1), a first amplifier input for receiving a reference voltage (V
12 Citations
20 Claims
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1. A current regulator circuit comprising:
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a first circuit node (32) which is operable to receive an external input voltage;
a transistor (M1) having an input, a first leg and a second leg, the first leg of the transistor being isolated from the first circuit node (32);
an amplifier (10) having an output connected to the input of the transistor, a first amplifier input for receiving a reference voltage (V REF ) and a second amplifier input connected to the first circuit node (32);
a low-pass filter (33) connected between the output of the amplifier and the first circuit node (32);
a current mirror (36) connected in series with the second leg of the transistor (M1) and having a first branch (38) for providing a regulated output current and a second branch (37) which connects to the first circuit node (32), wherein the first branch (38) is directly or indirectly coupled to an output stage (40), which comprises a further current mirror, wherein the further current mirror is an EMI-filtering current mirror. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 12, 13, 17, 18)
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10. A current regulator circuit comprising:
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a first circuit node which is operable to receive an external input voltage;
a transistor having an input, a first leg and a second leg, the first leg of the transistor being connected to the first circuit node;
an amplifier (10) having an output connected to the input of the transistor, a first amplifier input for receiving a reference voltage (V REF ) and a second amplifier input connected to the first circuit node;
a low-pass filter connected between the output of the amplifier and the first circuit node; and
,a current mirror connected in series with the second leg of the transistor, wherein the current mirror comprises a second transistor and a third transistor whose gates are connected together at a mirror node, the third transistor having an input branch connected in series with the second leg of the transistor to receive current and the third transistor having an output branch to mirror the received current as an output current (Iref);
a fourth transistor connected between the mirror node and a supply rail (Vcc); and
,a fifth transistor connected between the mirror node and another supply rail and having an input connected to the input branch. - View Dependent Claims (11, 14, 19)
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15. A current mirror circuit comprising:
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a first transistor (M7) and a second transistor (M10) whose gates are connected together at a mirror node (43), the first transistor (M7) having an input branch (41) to receive current and the second transistor (M10) having an output branch (42) to mirror the received current as an output current (Iref);
a third transistor (M8) connected between the mirror node (43) and a supply rail (Vcc); and
,a fourth transistor (M9) connected between the mirror node (43) and another supply rail and having an input connected to the input branch. - View Dependent Claims (16, 20)
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Specification