No-trim low-dropout (LDO) and switch-mode voltage regulator circuit and technique
View Patent ↗An optimized output voltage circuit and technique obtainable without trimming is set forth. A voltage reference circuit and method devoid of trim resistors comprising a high gain amplifier, a plurality of bandgap resistors, and at least a plurality of bipolar devices interconnected across circuitry in a predetermined configuration having emitter areas greater than traditional emitter areas of traditional bipolar devices is set forth.
1. A bandgap circuit devoid of a trim resistors comprising a high gain amplifier, a plurality of bandgap resistors, and at least four bipolar devices interconnected across circuitry in a predetermined configuration capable to produce a bandgap voltage (V BG ), to a first order, approximating a predetermined designed bandgap voltage (V BGDESIGN ), wherein individually, the emitter area of at least three or more of the four bipolar devices is greater than a traditional emitter area of an equivalent traditional bipolar device by a factor within a range of approximately 1.75 to 2.25, wherein the predetermined designed bandgap voltage (V BGDESIGN ) approximates a voltage in the range of 1.15 to 1.35 volts and the bandgap voltage (V BG ) approximates a voltage of within 10% of the designed bandgap voltage (V BGDESIGN ), and wherein the plurality of bandgap resistors are configured to be horizontally positioned in relation to a heat source approximately situated beyond a linear distance of approximately 200 μm.
2. The circuit of claim 1 , wherein the plurality of bandgap resistors are configured to be horizontally positioned in relation to a heat source proximately situated within a linear range of between approximately 200 and 500 μm.
3. The circuit of claim 2 , wherein the plurality of bandgap resistors are configured to be positioned with respect to one another in an alternating pattern such that no like resistor of the plurality is situated next to an identical resistor type of the plurality.
4. The circuit of claim 3 , wherein the heat source is power device.
5. The circuit of claim 1 , further comprising an output stage of a voltage regulator having a comparator, output driver, and feedback resistors R A and R B , wherein the feedback resistors are arranged and configured to be at least at a linear distance of approximately 175 μm from a proximate heating source.
6. The circuit of claim 5 , wherein the feedback resistors are arranged and configured to be at least at a linear distance of approximately 200 μm from a proximate power device.
7. A voltage reference circuit devoid of trim resistors comprising a high gain amplifier, two or more bandgap resistors each being horizontally positioned at a linear distance of at least 200 μm from a proximate power device, and four or more bipolar devices interconnected across circuitry in a predetermined configuration capable to produce a bandgap voltage (V BG ), to a first order, approximating a predetermined designed bandgap voltage (V BGDESIGN ), wherein each emitter area of each of the bipolar devices is greater than a traditional emitter area of a traditional bipolar device in one of a Brokaw cell, traditional bandgap circuit or an equivalent thereto, whereby the circuit is operable connected with an output stage circuit having a comparator, output driver, and feedback resistors R A and R B , wherein the feedback resistances are arranged and configured to be at a linear distance of at least 200 μm from a proximate heating source.
8. A method of improving a voltage reference circuit design to eliminate circuit trimming for a circuit producing a bandgap voltage (V BG ) to a first order, which approximates a predetermined designed bandgap voltage (V BGDESIGN ), comprising:
removing resistors and diodes associated with trimming,
repositioning each bandgap resistor to be horizontally positioned at a linear distance of at least 200 μm from a proximate power device, and,
replacing MOS devices with bipolar devices in a predetermined configuration.
9. The method of claim 8 , further comprising enlarging emitter areas of at least two bipolar devices comparatively to a traditional emitter area of a traditional bipolar device in one of a Brokaw cell, traditional bandgap circuit or an equivalent thereto.
10. The method of claim 9 , further comprising providing for operable connectability with an output stage circuit having a comparator, output driver, and feedback resistances R A and R B , wherein the feedback resistances are arranged and configured to be at a linear distance of at least 200 μm from a proximate heating source.
11. The method of claim 10 , further comprising reducing the resistance of each of the bandgap resistors.
12. The method of claim 11 , wherein the circuit is one of a low dropout (LDO) regulator, a switch-mode regulator, or a voltage regulator circuit.
13. The method of claim 9 , further comprising reducing at least a majority of resistance of all of the bandgap resistors by at least 5%.
14. The method of claim 13 , wherein the circuit is one of a low dropout (LDO) regulator, a switch-mode regulator, or a voltage regulator circuit.
15. The method of claim 13 , further comprising testing the circuit to produce a bandgap voltage (V BG ) to a first order within 10% of the predetermined designed bandgap voltage (V BGDESIGN ).